the elgi magazine

THE ELGI MAGAZINE
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THE ELGI MAGAZINE
Contents
Life Today
2
Chilling Out in Chinnar
A travelogue
2
Chinnar : Travelogue
Industry Insights
16
The Delightful Domain of Denim
Compressors in the making of fashion
24
Writing Instruments
From cave drawings to quill pens to ballpoints
32
Pressure Vessels
Compressed air and pressure vessels
38
Ceramic Tiles
A journey from the bowels of the earth to floors and facades
15
Denim : Compressed fashion
44
Business Spotlight
48
52
Air Separation
Elgi compressors in the production of industrial gases
The Odyssey from Parchment to Paper
Revealed : The art and science of papermaking
56
Nuclear Energy
64
5D Magic
66
The Alluring World of Aluminium
Nuclear energy : The atom power
Demystified
Compressors adding to the magic of movies
Compressors and the world’s most versatile metal
Compressed Air in Nature
74
Bergie Seltzer
Air in polar icecaps
Research & Innovation
74
Bergie Seltzer: Compressed air in nature
78
Oil-Free Screw Air Compressor
Efficient, economic, eco-friendly compression technology
82
Fuel Cells
The energy source of the future
Product Focus
86
Guniting
Concrete in a jiffy with Elgi compressors
78
Oil-free Air: Cutting edge technology
90
Auto Car Wash
Rollover car washing solution from ATS Elgi
93
Engineering Solutions
Showcase of products
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THE ELGI MAGAZINE
CHILLING OUT IN
Chinnar
Photos: Akber Ayub
The quietude had a surreal quality. The silence was unbroken, save for an
occasional whisper of branches, the distant call of a peacock or the quick
chirp of a bird flitting by. The intrusions only accentuated the stillness. It was
a slice of time sculpted by nature, meant to captivate all who came under its
spell. The moment seemed timeless, as if time itself was holding its breath.
Caught in that fragment of time the view soaked quietly into my psyche.
Blue mountains undulated close on the horizon forming a sweeping arc in
the surrounding wildness. Clusters of dark pregnant clouds drifted lazily
overhead against a light blue sky rendered luminescent by the sun dipping
behind the mountains. Elsewhere, puffs of white nimbus clouds stood out
like freshly picked cotton against the azure background. And scattered streaks
of cirrus edged in silvery gauze formed skeins on the darkening sky. An
unseen bird called out a yodel…
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The blue tint on nature’s canvas deepened as the minutes ticked by. And the
mountains lay supine, their contour much like that of a sensuous, recumbent woman. But
near her feet, the silhouette reared up into an angry, jagged outline
The blue tint on nature’s canvas deepened as the minutes
ticked by. And the mountains lay supine, their contour much
like that of a sensuous, recumbent woman. But near her feet,
the silhouette reared up into an angry, jagged outline. And
the hush of dusk... Like autumn leaves settling on a forest
floor, a veil of silence settled over the landscape. Breaking
the spell briefly, a puff of air rustled the foliage behind
me. Then a light breeze brushed my cheeks bringing with
it a crispy coolness that carried the hint of rain. I crossed
my fingers hoping to savour the panorama for a while
longer before rains arrived. But the rain gods weren’t in
a collaborative mood and let loose a drizzle that sent me
packing indoors into the mud-floored veranda fronting the
hut. I soon realized my folly though, and stepped out into
the misty rain, face upturned…
Four kilometres of strenuous hiking up a steep highland
had brought me to this wilderness camp earlier in the
day. I’d driven down in a taxi from Coimbatore – en route
from Bangalore – early on this mid-July Sunday morning to
taste a slice of the wild and to seek refuge in the stillness of
nature. The taxi had brought me up to the Eco-development
Centre at the Kerala forest check-post at Chinnar, just across
from the bridge over the meandering Chinnar River. The
rambling Chinnar forms the boundary between Chinnar
Wildlife Sanctuary in Kerala and the Anamalai Tiger Reserve
in Tamil Nadu. Here, guide Gopalan and two others – cook
Biji and man Friday Palanisamy from the eco-development
tribal committee – teamed up with me. My eco-package
included all meals during camping: tribal cuisine prepared
in river water. It was mid-day, so after a quick meal of simple
vegetarian food in a scrubby hotel at the centre – the only
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How to Reach
By Air:
Coimbatore-115 km. Kochi-208 km.
By Rail:
Nearest railhead is at Pollachi-60 km.
By Road:
Chinnar sanctuary lies on the Munnar-Udumalpet Road,
22 km from Udumalpet and 60 km from Munnar. Roads
are excellent.
Where to Stay
Forest camps run by eco-development tribal
committee, from their office at Chinnar check post.
Mud huts at Vasyapara, log houses at Thoovanam
and Kootaar. Tree houses at Kombakkayam, Kootar
and Karakkad.
one for miles around – I was set for my
tryst with the forest. The taxi then drove
us another four kilometres – my bag,
provisions, pots and pans and all – to
the drop-off point near the Champakkad
tribal settlement on the Munnar Road
(the sought after hill destination lay
just 60 km away.) We trooped out of
the car and the driver took a U-turn and
bid me farewell. I watched as my mode
of transport for the last several hours
disappeared into the distance. Gopalan
hefted my bag weighing well over fifteen
kilos, and the other two strapped on their
backpacks too, packed with provisions
and pots. Their homes lay en route,
they said – a modest settlement of 200
families located well over a kilometre
into the jungle. So we left the familiar
tarmac and ventured down a well-worn
track along scrubland and a rocky terrain.
Only old men and women were to be
seen lazing on front verandas of the mud
huts – the men, able-bodied women,
and all children barring infants having
gone on their habitual, daily foray in to
the forest to collect honey, gather goose
berries, and ferret out roots and tubers.
Clutches of hens, sheep tethered to
trees and few buffalos grazing nearby
accentuated the pastoral ambience.
Gopalan pointed out his home – mud
and thatch and peaked roof sitting under
a shady, gnarled old tree. After capturing
in my camera the rustic landscape under
the afternoon sun, we left the scene
behind and resumed our walk. Pambar
River came up next, flowing at a brisk
pace here over rocks and boulders. Tall
grass and bushes poked from clusters of
rocks strewn in its path. A new bridge
spanned the river and provided me with
a vantage point to capture the spirit
of the river with my Nikon. The trek so
far had been taxing enough, with my
camera-gear weighing a couple of kilos
strapped across my chest and mineral
A STRENUOUS TREK
A ragtag assortment of tiled and thatched
huts loomed in the distance after nearly
twenty minutes of trekking across the
deciduous forest that was interspersed
with thorny bushes, assorted cacti, and
green foliage of myriad shapes and sizes.
Trekking Options
Eco-tourism activities organized jointly by the forest department and the ecodevelopment committee include:
1. Trekking along rivers and to cultural sites (dolmens.)
2. Nature trail to the watch tower.
3. Trek to Thoovanam falls close to Myavoor village en route to
Munnar.
4. Tree house at Chinnar.
5. Trekking & camping in Machans at Karakkad Champakkad and
Koottar.
6. Trekking and camping at Vasyappara mud hut.
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water bottles and some quick bites
picked up from the hotel dangling
from a bag on my shoulder; but it took
on a different temper after another
kilometre. The second half of the four
kilometre journey brought up steep
hillsides, thorny bushes, overgrown
cacti, boulder-strewn paths, dry stream
beds, and narrow ledges along rocky
outcroppings. While my muscles
groaned after negotiating each boulderstrewn mound, Gopalan and company
skimmed over the obstacles with the
agility of nimble-footed mountain
goats. With skin the colour of dark coffee,
and lean and trim, they took birth in the
arms of the jungle. For them, this was
little more than a walk in the park. We
took another break on a dry stream bed
next, under a shady green canopy, more
for the photo ops it offered. Sun filtered
through foliage and leaves glowed an
iridescent green.
Most of Chinnar lies in a rain shadow
area, so during the first half of the year
searing sun baked the earth and withered
the vegetation and everything turned
bone dry. But with the first showers in
early June, the landscape witnessed a
miracle of sorts. Even with the sparse
rainfall, grass and vegetation sprang
to life and after only a fortnight of
intermittent showers, Chinnar turned
green all over. Sporadic showers in July
bring more colours to the pastures in
the plains, and hills cover themselves
in a hurry in fresh new vegetation all
lush and green. So, though my body is
perspiring under the mid-afternoon sun
and the unaccustomed toil, my eyes are
soothed by the splendid greenery of the
surrounding hills and the tree-covered
lowlands below. After skirting a pebble
strewn, lateritic hill, we come upon an
expansive plateau on a rocky outcropping.
We hadn’t come across a single soul after
leaving the ethnic settlement below, so
the sudden appearance of a tribal family
complete with grazing sheep and cows
took me completely by surprise. So this is
where a typical family spend its day. A fire
crackled nearby and Biji the cook pointed
out charred lumps in the fire: wild tapioca
We took another break on a dry stream bed next,
under a shady green canopy, more for the photo
ops it offered. Sun filtered through foliage and
leaves glowed an iridescent green
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Sporadic showers in July bring more colours to the pastures in the plains, and hills
cover themselves in a hurry in fresh new vegetation all lush and green
Topography and Climate
Declared a wildlife sanctuary in 1984, the 90 sq km wilderness has a mixed habitat
of thorny scrub land at lower altitudes to shola grasslands on the high ranges. Other
habitat types are deciduous forests and riparian regions. These are interspersed
with plains, hillocks, rocky terrains, and cliffs that together provide microhabitats
for varied life forms. The general terrain therefore is undulating with hills and
hillocks of varying heights. Bounded by Eravikulam National Park in Kerala to the
south and Anamalai Tiger Reserve in Tamil Nadu to the north and east, the Chinnar
sanctuary is contiguous to both. The undulating terrain has altitudes ranging from
500 to 2300 meters. This accounts for the sharp variation in its climate. While the
plains are sultry, the uplands tend to be cooler. Barring sporadic showers between
June and August, the main rainfall occurs between October and December. Annual
precipitation is around 350 mm and total rainy days are mostly under 50. The
recorded lowest temperature is 12° C and the highest 38°, with a mean annual
temperature of 36° C. Perennial rivers Pambar and Chinnar meander through almost
the entire length of the sanctuary. Both originate in the sholas of the upper reaches
including Munnar and form the major sources of water in the region.
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TRIBAL LIFESTYLE
Two more-or-less similar tribes, Muthuvans and Hill Pulayas, inhabit the sanctuary in scattered hamlets. Their life styles
though vary widely – the former engage themselves in growing ragi, corn and other produce, while the latter spend their
days foraging in the forest for honey, roots and berries. With new income from the self-managed ecotourism, they’ve now
stopped killing wild animals; and with good reason: They are paid Rs 400 each time they fill up the water tank at the mud
hut from far off mountain streams and Rs 300 apiece for every night spent in a camp. The rest goes to a community bank
account maintained in nearby Mayavoor village. Though the sanctuary now provides a livelihood option, they do maintain
their cultural heritage. Significant archaeological megalithic burial sites consisting of dolmens and cysts found near some
settlements speak of that heritage. Overall, the 11 settlements within the sanctuary have a significant impact on the forests
around them and vice versa. Launched by the forest department, the eco-development programme has made successful
efforts for evolving a model of biodiversity conservation in a landscape dominated by man.
tubers gouged out of the earth with
sickles that almost everyone carried
here. The family lazed on the edge of
the precipice while their lunch cooked
nearby. We took a breather, unburdened
ourselves, and relaxed on boulders. While
my companions partook of the family’s
lunch, I got busy with my camera.
We resumed our climb after only a
short rest, my overworked muscles were
thankful for a brief respite; but the hike
now grew tougher. Palanisami pointed
out that the last few hundred meters
had a twisting track that led not only
through large patches of lush foliage but
also boulder-strewn tracts and scrubland
riddled with the ubiquitous thorny
bushes and wild cacti. After a final bend
in the forest track, I got my first glimpse
of my destination: a mud hut perched
on a mesa atop the rocky cliff Vasyapara
and a couple of other structures behind
the hut. While my nimble-footed
companions legged across the last clutch
of rocks with nary an effort, I took my
time ending my journey of over three
hours of hiking across rough country.
And then, finally, here was the reward
beckoning me…a sight that at once…well,
brushed my soul. I forgot the aching
muscles and weary limbs as the breathtaking view unfolded before me.
NIGHT IN A MUD HUT
Palanisami unlocked the hut, went in
with his backpack and emerged a while
later, ushering me into my jungle abode
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for the night – mud floors and walls,
and thatched roof covered in bamboo
matting. The furniture was Spartan too
– just a double bed, with a clean white
sheet over it, pillows, and a blanket.
Clean bed linen had been packed in the
backpack but the windows were bare.
The attached bath had a western closet,
a rather grimy basin, and well-worn
buckets. The plumbing had stopped
working perhaps a long time ago. Spiders
and insects skittered into new crevices.
Maintenance and upkeep seemed a
foreign concept here. I decided to limit
my use of the bathroom to the bare
minimum. While I unpacked, the crew
got busy in the next-door shack. Shortly,
Palanisami reappeared clutching a steel
glass of black tea and biscuits. The tea
was drinkable, considering that the water
came from mountain streams and stored
in a plastic tank behind the shack. As the
evening wore on and dusk approached,
a campfire was lit and soon tongues
of flames leapt into the mountain air,
spreading a yellow glow over the mesa.
Before long, the whiff of hot coconut oil
wafted across from the shack, signalling
dinner in the making. As nature painted
the skies in a kaleidoscope of shifting
colours, and chirping birds flitted across
preparing to nest for the night, and
peacocks signalled with loud tweeting
calls, dinner was served on the veranda –
boiled rice, a differently coloured sambar,
and cabbage. But the ambience more
than made up for the frugal fare. With
no electricity, torch lights and batteryoperated lanterns provided essential
light. Dinner over, Palanisamy cleared
the plates and walked back to his shack. I
switched off the lantern, shifted the cane
chair to the small clearing and sprawled
in it beneath an infinite canopy of star
spangled blackness, the moon having
slipped behind a large mass of black
clouds. The night sounds of the forest
enveloped me. I was one with the wild
heart of Chinnar.
Another trek into the surrounding
woods was on the agenda next morning.
Hopeful of seeing some wildlife finally,
I donned tracksuits and set out with
my camera slung over my shoulders.
Gopalan led the way. Scrubland plateaus,
rocky hillocks, dry streambeds with the
green forest in the plains below and the
undulating mountains in the backdrop
greeted me on my morning jaunt.
Though clusters of dark, almost charcoal
clouds drifted across pale grey skies,
only sporadic drizzles came down. Birds
of different feathers – green bee-eaters,
tan coloured warblers, and black mynas
– tweeted and chirped. Fresh droppings
of wild bison, elephants, spotted deer,
even peacocks showed up intermittently,
but no wildlife came into view – not
even the endemic grizzly giant squirrel
considered the star attraction of the
sanctuary. Nevertheless, this place, I
reckoned, must surely be on the itinerary
of true nature lovers. As if to redeem
the situation, Gopalan came sprinting
with his binoculars. Pointing to the
forest in the plains below, he hollered,
“elephants!” Sure enough, I spotted a
herd, complete with a tusker and babies,
grazing on green leafy trees. While adults
munched on tufts of leaves wrenched
by a quick twist of their dextrous long
trunks, the babies were more interested
in the shade provided by the four pillars
and the roof of their mothers’ bellies.
A little later, the scene repeated itself,
but this time it was Gaur or wild bisons
feeding on a patch of grass in the forest
valley flanked by the undulant peaks. The
As nature painted the skies in a kaleidoscope of shifting colours, and chirping birds flitted across
preparing to nest for the night, and peacocks signalled with loud tweeting calls, dinner was served
on the veranda – boiled rice, a differently coloured sambar, and cabbage
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Flora and Fauna
Diverse flora apart, Chinnar Wildlife Sanctuary has a rich diversity of
fauna. With 52 species of reptiles, the sanctuary is rich in terms of
number of species. There are 14 species of fishes in the Chinnar and
Pambar rivers. There are also amphibians endemic to the Western
Ghats, like two species of tortoise, both endangered and adapted
to the dry deciduous forest. There are 29 species of snakes and
rare geckos and similar creatures. The dry open scrub forests are
excellent habitat for a wide variety of mammals, birds, butterflies,
and reptiles. Chinnar boasts of the only population of grizzled
giant squirrel in Kerala, with an estimated population of about 240.
The rare rusty spotted cat and Nilgiri tahr, elephant, tiger, leopard,
wild boar, sambar, spotted deer, barking deer, porcupine, wild dog,
common langur, bonnet macaque, jackal, sloth bear, Nilgiri langur,
jungle cat are some of the other important mammals found in the
Sanctuary. Gaur or wild bison, spotted deer, and samber are found in
the plains. The famous ‘white bison of Manjampatti’ has been found
here too. Avian diversity includes 225 species of birds. Chinnar thus
forms part of a viable conservation unit.
tribals have an amazing ability to spot
wildlife and identify their pug and hoof
marks, and their droppings. Pug marks?
“Yes, there are tigers and leopards,” said
Gopalan, “but rather few in number and
no census figures are available.” Given
that the Chinnar Reserve is contiguous
to the Anamalai Tiger Reserve, and with
a healthy population of deer and Samber
here, I reckoned that was quite likely. He
then regaled me with how his father was
once attacked by a leopard on a hillock
and how he barely managed to save his
skin. He also talked of recent elephant
attacks on tourists. An armed guard
would have served the visitors well, I
reflected.
After a hurried lunch of more of the
same fare, we packed up and began our
descend to the eco-centre at the Chinnar
check-post. After restocking supplies,
and completing payment formalities, the
four of us walked a short distance along
the empty Munnar Road before veering
off into the jungle once again – this time,
along the banks of the Chinnar River.
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Grizzled old trees with
branches leaning into the
river, water cascading
over little boulders, lush
green vegetation, dappled
sunlight playing on the
water, profound peace and
serenity
Grizzled old trees with branches leaning
into the river, water cascading over little
boulders, lush green vegetation, dappled
sunlight playing on the water, profound
peace and serenity all combined to cast
a spell as we followed the meandering
Chinnar. Gopalan explained that the
river swells as the monsoon peaks,
breaching its banks and submerging
the track we were now walking on. So
they take a different route to reach the
riverside log house to which we are now
headed. Yet, after a kilometre along the banks, we veered into
the surrounding rocky grasslands for the next two kilometres of
our journey. “You’ll have to hop from boulder to boulder along
most of the banks on that route,” said Biji, pointing to the track
we’d just left. Our new trail leads us into leafy scrubland, uneven
terrain strewn with rocks and boulders, shady vegetation and
sometimes a sudden grassy clearing. An hour later, as we came
around a bend in the track, the roar of the river filled the air.
And soon, a green-hued log house came into view – perched on
a rocky tableland barely twenty metres from the river. Though
we had started from the banks of the Chinnar River, we had
now fetched up at the Pambar once again. The roar came from
frothy water cascading over innumerable boulders in the water,
rounded and sculpted by the constantly flowing water over eons.
Except for the walls, which were made of wooden slats, and
cement flooring, the log house resembled the mud hut I’d stayed
in the day before, complete with an attached bath covered in
tin sheets. The windows had been left open and a patina of dust
covered the floor and the window sills. Thankfully the cotton
mattress had been left rolled up. Once again, it was midday, so
the crew engaged themselves in preparing lunch – but this time
on a wide rocky ledge right next to the flowing river under the
Blue
Mountains
Green
Vegetation
Red
Earth
White
Waters
Chinnar Wildlife Sanctuary
is regarded as unique in the
whole of Western Ghats due
its geological significance.
And the blue mountains
bordering the sanctuary is
a sovereign element in its
topography. The peaks range
in altitude from the 1845
metres tall Viriyootumalai
to the 2144 metres
Kottakombulmalai. Morning
mist curving around their
lofty heights creates myriad
moods: rush of inspiration in
poets and writers, romance
in tremulous hearts, and
A deciduous forest for half
the year, the spare monsoon
brings dramatic changes to
Chinna’s fauna, transforming
dry scrubland into a tapestry of
green. Giant cacti and thorny
scrub turn lush and verdant.
Flowering and medicinal plants
abound too. High altitude
shola grasslands are endemic,
and Alibiza Lathamii, an
endangered tree grows here as
well.
As the landscape withers
under the searing summer sun,
red earth takes centre stage,
revealing more and more of
itself each sweltering day. It is
not strictly red though, tending
more towards ochre. Tribal huts
bring out this colour vividly and
so do the well-worn trekking
trails snaking across the
sanctuary and gravelly plateaus
upland.
Come monsoon and
the Pambar turns into
a spirited river, gushing
over rounded boulders
and swinging past large
rocky knolls in white,
frothy waves – though
white water rafting is
not permitted, this being
a reserve forest. It flows
under the Pambar Bridge
in a tumbling current
of froth and surf, while
around the log house,
it reveals an even more
ebullient character.
humility in mere mortals.
COLOURS OF
CHINNAR
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As twilight retreated into the enveloping folds of night, a new
element entered the scene: a full moon! And it went on to
create a different kind of magic. Slowly, almost imperceptibly,
the white orb crept up over the foliage and smiled benignly
with a silken brightness
shade of a cluster of large leafy trees.
Whiff of hot coconut oil and wood
smoke vied with the smell of damp earth
and moist vegetation…until lunch was
served. That done, I took a siesta. It was
late afternoon when I ventured into a
lonely walk along the riverbank under
the cool shade of an unbroken green
canopy. Along this stretch, rugged, treecovered granite outcroppings rose above
the river on both banks but elsewhere lay
grassy embankments and lines of trees.
The rocks bore wide cracks and were
highly sheared and fractured in places. I
was taken in by the changing nature of
the banks. The river was fairly swollen
following nearly a month of monsoon
in the hills of Munnar and beyond. The
ground was covered in a carpet of dry
leaves of myriad hues; vines as thick as
my arms snaked and twisted their way
from the forest floor to the limbs and
trunks of trees, boulders of all shapes
and sizes lay strewn on the banks and
in the river, and the roar of the galloping
river reverberated in the cool air. Here,
nature stamped its dominance on the
landscape almost completely. It seemed
to proclaim in no uncertain terms that
this virgin, primeval piece of real estate
is indeed its domain. All too soon, the sun
was in setting mode and dipped behind
the tall trees lining the banks, and in a
while colour began draining from the
sky and twilight approached. As birds
headed for their nests, a steady cool
breeze swayed leafy branches overhead.
I sought refuge in an inviting niche on
a large boulder and soaked in the magic
of the moment. It was a moment that…
well, stole my heart and I captured it
in my Nikon. But the best was yet to
come. As twilight retreated into the
enveloping folds of night, a new element
entered the scene: a full moon! And it
went on to create a different kind of
magic. Slowly, almost imperceptibly, the
white orb crept up over the foliage and
smiled benignly with a silken brightness.
While puffs of silvery cloud shone in its
surrounding halo, it had reserved its best
for the rollicking waters of the Pambar.
The river had turned into a tapestry in
silver; looming columns of trees lurking
in inky shadow on the twin banks
formed a brocaded border, rounded
boulders strewn in the river shone
silverlike …but never mind! Sovereign
elements in nature sometimes paint a
picture that is beyond words. As I stand
transfixed, I reflect how a scene that was
beautiful by day has transformed into
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something magical by night. Even when
the customary campfire was lit and its
yellow rays worked their magic on the
rocky tableland, my eyes kept wandering
to the moon and the river.
SOUL OF A RIVER
Day three was to be in a tree house,
perched thirty feet above the forest floor,
but since it was under maintenance
at the time, I opted to stay back at the
riverside log house. After the customary
tea and biscuits at the crack of dawn, I
ventured into the river for a bath. I tried
the water close to the bank, in the lee of
a rocky mole and flinched, not realizing
how cold it could be. But washing in the
river, at dawn, under clear blue skies,
serenaded by chirping birds and letting
the tumbling surf massage your limbs
beats a plush Jacuzzi or a bathtub any
time. The day had started on a relaxing
note and that continued with a riverside
lunch served piping hot and a siesta on
the banks until late afternoon, when
Palanisami suggested a trip to the
tree house because “it is located at the
confluence of three rivers and is great for
wildlife viewing.” A short trek of about
twenty minutes along a well-worn trail
brought us to the confluence. En route,
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we had a preamble perhaps to sighting
bigger denizens of the sanctuary. A wild
hog dashed across our path and jungle
fowl and a pair of peacocks scratched
around in a patch of low underbrush.
Palanisami picked up a porcupine quill,
and a broken deer antler bleached white
by the sun.
At the conflux, ebullient Pambar
tumbled in from my right and slammed
into sedate Chinnar streaming in from
my left. The combined waters now set
forth in a new direction tangential to the
constituent rivers and in a new avatar
called the Kootar River that sallied forth
into Tamil Nadu territory. Luxuriant trees
with massive trunks stood like sentinels
on the banks and perched on one such
stocky, knotted trunk was the tree house.
A rope ladder dangled from its weatherworn balcony. The bathroom had fallen
off and rested on another branch lower
down. Few tribesmen were on the banks
angling in the water. An old man – very
lean and very dusky – with folds of cloth
wound around his head and donned in
a chequered mundu hitched around his
waist, threw a circular net into the water
with a deft flick of his hands. I took out
my Nikon. After I was done with clicking
The evening wore on…colours on the sky deepened…and as the sun melted into the
far horizon, the river was bathed in golden lights – as thick and rich as nectar
pictures, Palanisami led me to the banks
of the Chinnar River for a walk, promising
a different experience. And boy, was he
right!
Fawn hued boulders in myriad shapes
and sizes lined the banks interspersed
with little sandbars. The smooth, sandcoloured rocks were in the river too, but
barely created a ripple. Chinnar had a
calm, dignified character, and flowed
mellifluously without hurry. Orange
shafts of sunlight played on the waters
creating shifting designs. Foliage leaned
into the river from the banks forming
a green pavilion woven with flecks of
sunlight. The evening wore on…colours on
the sky deepened…and as the sun melted
into the far horizon, the river was bathed
in golden lights – as thick and rich as
nectar. The scene had a mesmerising
quality, something elemental, with the
power to stir one’s
soul; and the air
had a sublime tenor
too.
You
could
perceive the subtle
romance of the
river…nay, its very
soul.
And if you are free
at heart, you might
just discover the
way to an unknown
part of yourself...and
be humbled by the
experience.
n
Useful Info
Forest Info Centre
(Wildlife warden’s office)
Tel/Fax: 04865 231587.
Emails:
[email protected]
[email protected]
Website:
www.chinnar.org
Charges:
2-day Valley Safari: Rs 3500 per
head.
Mud hut: Rs 2500 per head.
Riverside log house: Rs 1500 per
head.
Tree house: Rs. 1000 per head
(includes all meals.)
Trackfinder Adventure, Munnar:
04865 232 608
Kerala Tour Co, Kochi:
0484 236 9121 / 98461 62157.
Email:
[email protected]
THE ELGI MAGAZINE
17
The Delightful
Domain of
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Denim
THE ELGI MAGAZINE
The year: 1600. The place: City of Nimes,
France. The event: The very first denim
fabric in the world is created. City of Nimes
translates to Serge de Nimes in French
and that name got attached to the new
fabric which, over time got shortened to
de Nimes and eventually to denims – a
name first listed by Webster’s dictionary
in 1864. If the beginning of this one-of-akind fabric is interesting, its later journey
is truly fascinating. That journey began
when commercial production of denim
started in the ensuing years. The first
denim fabric on a commercial scale was
created in Chieri, a town near Turin, Italy
using raw materials from Nimes. These
first fabrics were then sold through the
Italian port of Genoa that later ended
up as all-weather pants for sailors of the
Genoese Navy. Continuing this maritime
connection, legend has it that Columbus
used denim for his sails! But what about
the name “Jeans”? Italian sailors from
Genoa traditionally wore cotton trousers
and later switched to the new fabric
from Nimes that offered durability and
comfort. And the French call Genoa
and the people who live there, “Genes.”
That name stuck to their cotton pants
too. And “jeans” is a later adaptation of
that original name for the sailors work
clothes. So, even though, according to
archaeological findings cotton fabric
existed nearly 5000 years ago – in the
Indian subcontinent to be precise –
denim is just over 400 years old.
Haute Couture
There are even more tidbits of history
related to denims and jeans. The U.S.
Navy introduced the first bell-bottomed
trousers made of denim in 1817 to permit
ship’s deckhands to roll up their pants
above the knee when washing down
the decks. Scoot to the year 1848. Gold
is discovered across California and the
famous gold rush begins. The sturdy
“To match the copper rivets,
Davis started stitching
jeans using orange
coloured threads – that
later became as iconic as
the apparel itself”
all-weather pants made of denim
becomes a hit with mine workers. And
in 1853 Bavarian-born businessman Loeb
Strauss, later known as Levi Strauss,
sees a business opportunity and starts
a wholesale business, supplying this
rugged cotton twill textile to gold rush
miners. Finding that under the rough
working conditions, the seams of the
pockets on the trousers tore easily, Jacob
Davis, a Nevada tailor, designed denim
jeans with copper rivets at the pocket
corners to prevent the tears. And, to
match the copper rivets, Davis started
stitching jeans using orange coloured
threads – that later became as iconic
as the apparel itself. What about the
signature labels on the back pockets
of jeans? In 1936, Levi Strauss sewed a
little red flag next to the back pocket
of his jeans marking the beginning of
that signature label. Blue jeans became
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19
“Myriad of denim fans from movie actors, rock band stars, TV personalities and a host of
others all endorsed and drove the trendy cowboy image of jeans to new heights of fame,
and indeed fortune. And in the 1980’s jeans went from working clothes, trendy teenage
wear to high fashion“
the working cloth of choice for people
who lived and worked in hard, tough
conditions like miners, ranchers, farmers,
railroad workers and the like. Jeans were
not stylish or fashionable then; they
were merely durable. But during the late
1930’s cowboys often wore jeans in the
movies giving them a more acceptable,
even a fashionable image. World War II
made jeans popular among American
soldiers and thereafter it just spread
all across the world. After the war, rival
companies like Wrangler and Lee began
to compete with Levi’s for a share of
the international market. Interestingly,
jeans were called “waist overalls” in the
US till the late 1950s, when teenagers
began using the adaptation “jeans” of
the original French name and thereafter
Levi Strauss officially adopted the name
too. A myriad of denim fans from movie
actors, rock band stars, TV personalities
and a host of others all endorsed and
drove the trendy cowboy image of jeans
to new heights of fame, and indeed
fortune. And in the 1980’s jeans went
from working clothes to trendy teen age
wear to high fashion. Famous fashion
designers like Gucci got into the business.
Still later jeans made it to the catwalk of
big fashion houses, and haute couture
designers like Chanel, Dior, Chloe and
Versace added them to their collections.
A wide array of clothing from dresses,
shirts and shorts to skirts, coats and
jackets were fashioned out of this trendy
and versatile fabric. Denim hasn’t looked
back ever since. This spirit of enterprise
and innovation has been a constant
companion of denims and jeans as it
evolved through the years from the time
the fabric was created in France more
than four centuries ago. Continuing that
legacy, this fabric and this iconic piece of
apparel that has literally swarmed the
world – there’s not a country left where
denim in some form is not used – has
spawned countless business empires
that span the globe today.
From Bale to Fabric
If the history of denim is fascinating,
its creation is no less captivating. Raw
cotton picked from the fields goes
through a plethora of processes and an
amazing array of changes before it is
transformed into a pair of jeans or other
pieces of apparel that adorn store shelves
world over. To put it simply, raw cotton is
20
THE ELGI MAGAZINE
INDUSTRY INSIGHTS
image: lightfootfarms.com
image: lightfootfarms.com
image: lightfootfarms.com
image: lightfootfarms.com
Clockwise from left : carding in-feed, carding, roving, drafting
first spun into yarn and the yarn is then
woven into denim. But that is like saying
attach a pair of wings to a cylindrical
body, then attach a pair of propellers to
the wings and you have an aircraft ready
to fly. Spinning and weaving are the two
primary processes in the manufacturing
of denim, but each is a gargantuan
industry in itself involving innumerable
operations, processes and treatments
performed by a mind-boggling array
of ultra-fast, state-of-the-art machines
that take raw cotton on a meandering
journey from fibre to yarn to fabric to
garment.
According to archaeologists spinning
began some 20,000 years ago when
animal and plant fibres were spun into
yarns using very primitive tools such as
stones and sticks – and hands and legs.
Modern technology uses hands and legs
too…but to operate electronic switches
and buttons that precisely control
a myriad of finely-tuned, definitive
operations.
The process begins with opening the
bales of cotton. Carding operation then
removes mineral impurities, foreign
matter and very short fibers, untangles
cotton into loose fibres so that cotton
takes the form of a web which is then
converted into a rope-like form, the
sliver. The carding machine is sometimes
called the heart of a textile mill since
carding operation decides the final
quality of the spun yarn. Carded slivers
then go through a combing operation
that forms parallel tufts, which then
pass through what are called Draw
Frame and Speed Frame that twist the
slivers into a thinner form and winds
them on bobbins. The drawing process
produces a single, homogenous and
uniform sliver called ‘Roving’ from a
number of carded and combed slivers.
A Ring Frame operation then converts
the Roving to an even thinner form
called ‘Cop’. Hairs on the thin,
precisely twisted Cop is removed by
a final conditioning process and
wound on large cones ready for
spinning.
Spinning involves twisting the sliver to
form a yarn. Yarn can be spun through
different processes but the most popular
THE ELGI MAGAZINE
21
image: lightfootfarms.com
image: lightfootfarms..com
are open-end and ring spinning that
produce a continuous filament of
interconnected fibres. Other processes
like friction spinning and air-jet
spinning are used selectively in specific
cases. The spun yarn or thread is now
ready to embark on the next stage of its
metamorphosis in to a fabric.
Warp and Weft
That stage is weaving: a process that
forms the very warp and weft of
the fabric, carried out in an intricate
machine called a loom. Warp refers
to the longitudinal yarns that run the
length of the fabric while weft yarns
run laterally across the width of the
fabric – both interlaced with each other
in desired sequence and pattern to
form the fabric. However, in the case
of denim, both the yarns go through
number of additional processes before
weaving can begin. The warp yarn and
the weft yarn receive distinctly different
treatments: traditionally, the warp yarn
is indigo dyed while the weft threads
are undyed or bleached white. Moreover,
since warp yarn needs to be sufficiently
strong to withstand stress and strains of
the weaving process, it is strengthened
by dipping the yarn in starch and other
stiffening agents in a process called
‘Sizing’ to increase its strength. But for
this process to begin, the yarns need
to be first put together parallel to each
other. Some 400 to 600 threads from
individual cones housed inside a steel
framework called a ‘Creel’ are drawn
together by a warping machine to form
a horizontal sheet made up of individual
threads, then wound on a wide spindle
to form what are called Warping Beams.
This process is therfore called Warping
or Beaming. In most cases, the number
of threads in a warping beam sheet may
not be sufficient to create the required
width of the woven fabric. So warping
sheets from multiple beams are drawn
together side by side to make a single,
broader sheet that matches the width
of the required fabric (generally 190
cm.) Dyeing is next. The yarn sheet is
drawn through chemical vats guided
indigo threads (weft)
THE ELGI MAGAZINE
by appropriately placed multiple rollers,
where it is washed with caustic and
washing soda. After passing through
another set of tight rollers to squeeze
out the excess water; the yarn sheet is
then passed through dyeing troughs
containing indigo dyes, then passed
through multiple sequence of rollers
where it is exposed to air for oxidation
and development of the dye on the yarn.
The dyed yarn is then washed with fresh
water repeatedly, squeezed through
rollers to wring out excess water before
finally sending it over number of steamheated drying cylinders or drums. Sizing
follows next where the sheet is similarly
drawn through vats containing chemical
formulations. The object here is to
improve yarn strength by chemically
The warp yarn and the weft yarn receive distinctly
different treatments: traditionally, the warp yarn
is indigo dyed while the weft threads are undyed or
bleached white
white threads (warp)
22
image: lightfootfarms.com
INDUSTRY INSIGHTS
“Air jet looms are used most commonly for weaving denim, where a jet of air ejected through
strategically placed nozzles all along the cusp of the ‘V’ within a ‘Reed’, pick and transport the
leading end of the weft thread at a very high speed from one side of the weft sheets to the other”
binding the fibres with each other and
also to enhance its friction resistance
by coating the yarn with appropriate
chemicals. Dyeing and sizing follow
sequentially in a
single, extended
machine in what is called the continous
sheet dyeing and sizing process where
the warp sheet is sequentially dyed,
oxidized, dried and sized all at one go.
Warp Yarns
Air Jet
Woven
Fabric
And now, finally, we come to weaving –
and the engaging domain of looms.
As stated, weaving is the process of
interlacing weft threads across warp
yarns and this task is performed by a
loom. To facilitate this interlacing, warp
yarn sheet is bifurcated & opened in the
form of two layers or sheets to form a
‘V’ – much like interlocked fingers
pointing in opposite directions – and
weft thread is inserted in between the
two layers inside the cusp of the ‘V’ in an
operation called ‘Shedding’. The insertion
can be achieved by number of means –
using a shuttle that runs to and fro within
the opened out layers of warp sheets, or
by other means called Projectile, Rapier,
Air current, Water current etc depending
on how the weft thread is transported
within the two warp layers from one
side to the other. Manual or powered
traditional looms employ the shuttle, but
this has a serious drawback: speed – it is
far too slow for mass production and is
now almost obsolete. The other four use a
shuttle-less weaving system and operate
at high speeds. However, air jet looms
are used most commonly for weaving
Filling Yarns
Air
Filling Yarn
denim, where a jet of air ejected through
strategically placed nozzles all along the
cusp of the ‘V’ within a ‘Reed’, pick and
transport the leading end of the weft
thread at a very high speed from one
side of the weft sheets to the other. The
Reed, made up of individual elements,
forms an elongated niche within the
‘V’ through which the weft thread zips
across much like a train zipping through
a tunnel. Once the thread reaches the
opposite side, the trailing end is snipped
off creating another leading end ready
to run across the Reed. Timing of air
nozzles are precisely controlled by
computer programmes that actuate
multiple solenoid valves regulating the
flow of compressed air sequentially to
the appropriate nozzle that is next in line
to take up the approaching leading end.
Water jet system is obviously unsuitable
for denims, its use limited mainly to
synthetic fibres that are impervious to
wetness. Though compared to Rapier
and Projectile looms, air-jet looms are
less versatile they are nevertheless
very economical. In this state-of-the-art
weaving technology, weft insertion done
with the help of compressed air with
computer controlled timing results in
a very high insertion rate of up to 1800
metre per minute.
The Diagonal Twill Pattern
What gives denim the signature
diagonal twill pattern on its reverse
side? If alternate warp yarns within the
warp sheet are grouped together to form
the two separate and identical layers
forming the ‘V’, it is called 1/1 warp-faced
THE ELGI MAGAZINE
23
It is this staggered pattern of
interlacing, namely three warp yarns
then a weft thread, next, one warp yarn
then one weft thread, again three warp
yarns and so on, that produces the
typical diagonal twills on the reverse side
twill construction. But if, after one warp yarn goes in to one layer,
three subsequent warp yarns are grouped into the other layer, it
is called 3/1 twill construction. Moreover, this sequence does not
begin at the same point for subsequent weft threads; rather, the
start is staggered for each succeeding weft thread that is ready
to run. It is this staggered pattern of interlacing, namely three
warp yarns then a weft thread, next, one warp yarn then one
weft thread, again three warp yarns and so on, that produces the
typical diagonal twills on the reverse side.
The woven fabric wound on a beam is offloaded from the loom
at regular intervals, and a strict regimen of inspection follows
that looks for weaving defects, bleaching and dyeing defects
like uneven or patchy dyeing, oil or other stains etc. That done,
the fabric goes through various finishing processes, such as
brushing, singeing, washing, impregnation for dressing and
drying. Brushing, and singeing with a gas flame, eliminate
surface defects and ‘hairiness’ and produces a flawless, smooth
surface. Dressing regulates the rigidity of the fabric while
compressive shrinking imparts anti-shrink properties ensuring
dimensional stability. At the end of these processes, the final
product is categorized according to quality. Completely flawless
fabrics would be ready for dispatch while the defective ones are
sent for further corrections.
Where does India stand in the world denim market? Indian denim
manufacturers enjoy pride of place in the world today. Cutting
edge technology, inspired innovation and uncompromising
quality have been the mantra for most of the leaders in the
field. KG Denim, located in the peaceful environs of Karamadai,
60 km from Coimbatore, is typical. Set up nearly 20 years back,
this premier denim and apparel fabric manufacturer caters to
leading fashion brands and retailers worldwide, sourcing high
quality yarn from mills in India and abroad. The denim factory
24
THE ELGI MAGAZINE
sprawls across a 25 acre estate, while apparels are manufactured
in a sister concern 10 km away that turns out the widely known
‘Trigger’ brand of jeans and other apparels. Employing shuttle
less weaving with high-speed air jet looms sourced from Picanol
& Toyota to weave fancy yarns and assorted blends, KG Denim’s
various quality accreditations speak for themselves.
Air jet looms apart, compressed air plays a key role in the textile
industry at various stages of manufacturing, specifically in
spinning and weaving operations – from bale opening to yarn
production and weaving to sewing apparels. Beginning with
carding, then combing process, winding slivers on bobbins, to
coping and speed and ring frame operations compressed air
is indispensible in the textile manufacturing process. And Elgi
has been a name synonymous with air compressors. Elgi ’s oilfree rotary screw air compressors are widely used in the textile
industry, both in India and abroad. n
advertisement
THE ELGI MAGAZINE
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26
THE ELGI MAGAZINE
INDUSTRY INSIGHTS
From cave drawings to quill pens to ballpoints.
Writing
Instruments
The history of writing instruments
is the history of civilization itself
for man has recorded and conveyed
thoughts and feelings through symbolic
representation in one form or the other
since very early times. The story of
man has always been recorded through
drawings, signs and words. Even though
the cave man’s first inventions were the
hunting club and skinning and killing
tools, he soon adapted some of these
into the first writing instruments and
began scratching pictures and symbols
on walls of his caves with pointed stone
tools. Since millennia, cave drawings
have been telling stories from the daily
life of early man.
Primitive writing instruments served
man for a long time before inventions and
innovations took writing instruments to
the next level. Fast forward to the Roman
Empire: Early Romans used wax tablets
for writing. A thin layer of wax was
applied to a wooden surface and scribes
carved into the wax with metal or bone
styluses. In parts of Asia, thin brushes
were used for painting, calligraphy and
finally writing, using ink made from
carbon black, indigo, berries, or ink culled
from squid, all mixed with oil or water.
Before long, writing took a quantum leap:
Early inventors found the hollow channel
of a bird’s feather a natural ink reserve
and the quill pen came into being. The
tail feathers of geese were considered
most adaptable to the pen. The English
word, “pen” is actually derived from the
Latin word for feather, “penna.” Inventors
used their ingenuity to produce a similar
man-made pen that would hold more ink
and not require constant dipping into the
ink well. The invention of paper brought
a timely fillip to the evolution of pen and
ink. Pens and ink in their various forms
are actually thousands of years old. Over
time, the quill pen and its later avatars
have been used to write documents that
transformed world history. Beginning
from around the seventh century, the
quill pen has been used to write such
historical documents as the Magna Carta
and the Declaration of Independence by
the US. Through much inventiveness and
ingenuity, the fountain pen evolved after
nearly a thousand years of using quill
pens. A Muslim caliph in present-day
Egypt takes the credit for commissioning
the invention of a pen with an ink
reservoir shortly before 1000 A.D. But
THE ELGI MAGAZINE
27
the oldest preserved fountain pen was
created by M. Bion in 1702 for King Louis
XIV. Then, in the late 19th century Lewis
Waterman, an insurance salesman,
invented what would become the most
popular fountain pen in modern use.
Throughout the heyday of fountain
pens, during the late 19th and early 20th
centuries, major pen manufacturers such
as Sheaffer, Waterman, and Parker came
out with more convenient pen designs
and refilling systems. And in 1879 in
Providence, Rhode Island, Alonzo T. Cross
invented the stylographic fountain pen,
which was actually a precursor to the
ballpoint pen.
Hungarian, Laszlo Biro set out to re-invent the pen. He
fitted a tiny ball in the tip of his newly designed pen
that was free to turn in a socket. As the pen moved
along the paper, the ball rotated, picking up ink from
the ink cartridge and transferring it to the paper
Early fountain pens had a serious
drawback. Even in early 20th century,
the ink used in pens took a long time
to dry, leaked and smeared easily. Then
inventors observed that printing ink
used in newspapers dried more quickly
and was relatively smear free. But
printing ink was too thick to be used in
a fountain pen, so a Hungarian, Laszlo
Biro set out to re-invent the pen. He
fitted a tiny ball in the tip of his newly
designed pen that was free to turn in
a socket. As the pen moved along the
paper, the ball rotated, picking up ink
from the ink cartridge and transferring
it to the paper. His efforts produced
what we know today as ballpoint pens.
Although others are credited with the
invention of the device, Biro was the first
to mass-produce and sell ballpoint pens,
starting 1944. He did this in Argentina
under an Argentine patent. Even though
it was American leather tanner John
Loud, who officially patented the first
“roller ball tipped marking pen” in
1888, he never produced the pen that
he had patented. Indeed, the ballpoint
pen went through several failures in
design throughout its early stages. Many
patents worldwide are testaments to
failed attempts at making these pens
commercially viable. However, following
World War II, ballpoint pens were
available commercially in most parts of
Europe and US. When Biro’s company
folded up in the early 1950s, he was hired
by Frenchman Marcel Bich. With Biro’s
28
THE ELGI MAGAZINE
help, Bich created the first inexpensive
ballpoint pen. Bich’s invention had a
clear barrel, wrote smoothly and did
not leak. Bich named the pen “Bic,”
after himself. Then, in 1954, Parker Pens
introduced its first ballpoint pen called
The Jotter, which was a runaway success.
Interestingly though, pens that contain
ready-to-use ink inside them have only
existed for about the last 130 years.
Today, the ballpoint pen, or ball pen,
has become the most popular writing
instrument in the world. Over myriads
of inventions, and a variety of processes,
tests and failed attempts, the design was
finally perfected and began dominating
the market in the 1950s. The means and
the technology of bringing together all
the materials that make up these pens,
from the specially formulated ink to the
tungsten carbide ball, is an intricate and
elaborate process.
Roller Point
and Ballpoint Pens
Ballpoint pens use a highly viscous,
oil-based ink with a consistency
similar to molasses in their
cartridges and refills, while roller
ball pens use thinner, water-based
ink with a consistency close to
that of water. Because of the thin,
water-based ink, the cartridges and
refills of roller pens tend to dry
out easily and therefore they are
capped tightly, though some of the
more expensive models solve this
problem with specially designed
ink distribution. This makes them
more expensive. With ballpoint
INDUSTRY INSIGHTS
Anatomy of a ball pen
clip
joint ring
spring
ink catridge
thrust device
push button
The various components that make up the body of the pen and the refill are
generally molded in plastic using a variety of different molds. In expensive models,
the refill is made of brass or steel rather than plastic
Construction of the Ballpoint Pen
A ballpoint pen dispenses ink from an ink
cartridge or refill via a metallic sphere
at the tip of the refill. The removable
refill or cartridge can be replaced when
empty. Some ball pens have a springloaded refill or cartridge where the tip
can be retracted into the body of the pen
or deployed by a button at the top of the
pen. A variety of components makes
up these pens, made of materials like
plastic, metal and chemicals. In most ball
pens, the writing sphere or ball is made
from stainless steel, nickel carbide or
tungsten carbide steel. In metal pens, the
body, ink cartridge and spring are made
of brass, aluminum or steel. The push
button, ink cartridge, cap and tip are
generally made of plastic. Manufacturers
use a variety of plastics, including highdensity polyethylene, vinyl resins and
pens however, the ink does not
evaporate, so a cap is not required.
Additionally, the writing tip is either
capped or is retracted into the pen
when not in use.
While low-quality ballpoint pens
can leave blobs of ink on the page
or may skip, leaving blank areas on
the paper, roller ball pens distribute
ink more evenly and are free from
these defects. However, due to the
low viscosity of the ink, if the pen
point remains in contact with paper
for sometime, ink can soak into the
paper at that spot, leaving a blot.
Ballpoint ink on the other hand
is oil-based and dries on contact,
and so it does not usually smear.
thermosetting plastic, which remain
rigid when cooled after molding.
Manufacturing Process
There are three distinct steps in the ball
pen manufacturing process, and they
take place separately. Ink is mixed in large
vats, with computer sensors monitoring
the timing and temperature. Most Indian
companies though import the ink. The
ball tips are manufactured separately
either in-house or in another unit.
Generally, these are purchased from an
outside supplier, and pen manufacturers
produce the remaining components by
metal stamping and molding processes.
The various components that make
up the body of the pen and the refill
are generally molded in plastic using a
variety of different molds. In expensive
models, the refill is made of brass or
Another difference is that while
the oil-based ink of a ballpoint pen
will not run, even if the document
becomes wet, the water-based ink
in a roller ball pen will run if the
page becomes wet, leaving the
writing illegible in most cases.
The refills in a ballpoint pen last
longer too. Why? Because the ball in
a ballpoint pen distributes very little
of the viscous ink onto the page
during writing, whereas the thinner,
water-based ink in a roller pen goes
through the refill more quickly,
partly because the ball distributes
comparatively more ink, but also
because the cartridge ink tends to
evaporate while the pen is in use.
THE ELGI MAGAZINE
29
Space Pen
ultra hard
tungsten carbide
ball
The Biro pen is actually the
precursor of the Space pen. In
1940, the Royal Air Force of the
British licensed the Biro pen and
manufactured them for RAF aircrew.
They were found to work much
better than fountain pens in the
decreased atmospheric pressure at
high altitudes – and more effective
than pencils.
However, as part of the frenzied
space race in the United States
during the 1960s, NASA wanted
a writing instrument that would
work in zero gravity. Up until
then, astronauts involved in the
Mercury and Gemini missions had
been using pencils to take notes
Lubricant
in space since standard ballpoint
pens did not work in zero gravity.
While the Russians continued to
use the pencil, US inventor Paul C.
Fisher independently developed
a space pen. Once perfected, he
sent samples to NASA, which
ended up buying 400 of his pens.
Fisher patented his AG-7 AntiGravity Pen in 1965. Beginning
with the Apollo 7 Mission in 1968,
these ballpoint pens became the
exclusive writing instrument used
on space missions. The Fisher AG-7
space pen and cartridge worked
well in zero gravity, under extreme
temperatures, even underwater
and upside-down. The secret was
the pressurized nitrogen gas filled
Surfactant
steel rather than plastic. And once all the
pieces are finished, trimmed, cleaned and
inspected, they are ready for assembly,
which takes place in a separate section.
To get back to manufacturing, let’s look
at the ink first. The inks for ball pens
are made of a combination of dyes,
lubricants, thickeners and preservatives.
Ink is manufactured by combining a
variety of such chemicals, which are
THE ELGI MAGAZINE
gas plug
in to the refill on top of the column
of ink and sealed with a gas plug. A
sliding float kept the gas away from
the ink. Fisher pens continue to be
used on all manned space flights
by the USA and the USSR including
the Apollo missions, the landings on
the moon, the space shuttle flights,
the Russians’ Sojus flights, the MIR
space station missions and the
International Space Station. Fisher
space pens also write in freezing
cold and desert heat, from minus
340C up to plus 1430C, as well as on
oily and greasy surfaces. Honouring
its spectacular success, the Fisher
Bullet Pen was featured in the
Museum of Modern Art in New York.
aluminum tube –, which is filled with
ink by a pneumatically actuated injector.
To remove entrapped air in the tube,
the ink tubes once assembled with the
ballpoint, are centrifuged to eliminate
any air bubbles. To prevent drying in the
tube, the top of the ink column is topped
off with a small quantity of jelly to keep
air out, or sealed with a small plastic cap.
Thickener
Pigment
30
Sliding float separate ink from
pressurized nitrogen cas
mixed together and heated or cooled in
order to facilitate the necessary chemical
combinations. It has to be somewhat
thick and slow drying in the refill or ink
cartridge, and rapid drying once it is
on the paper. This ensures the ink will
flow without clogging and dry quickly
due to absorption and evaporation once
it is on paper. The ballpoint is then
attached to the ink refill or cartridge –
an extruded plastic tube or a brass or
Tungsten Carbide Balls
The ball of ballpoint pen is made generally
from tungsten carbide steel that is
placed in a tray with a fatty additive. The
tungsten carbide balls are baked in an
oven until they become almost as hard
as a diamond. The balls are then ground
between two flat surfaces that produce
a smooth but microscopically textured
surface made up of innumerable pits
and plateaus. The pits hold the ink in
reserve while the plateaus come into
contact with the paper and spread the
ink to write. The metal tips that hold the
ball are made of machined brass, high-
INDUSTRY INSIGHTS
Heating Jacket
Hopper
Extruded Product
Pressure Screw
Die
The injection moulding process for
the plastic parts of ball pen
Plastic is generally used for the
body of the pen because it is not
only relatively inexpensive but
also lightweight and corrosion
resistant
grade stainless steel or nickel silver that
are resistant to corrosion. Stock in the
form of a wire of 1-1.5 mm in diameter
is fed into fully automatic machines
that cut the required length for the tip,
bore it to the required inner diameter to
make it hollow, form the socket at one
end, insert the ball and seal it to hold the
ball, all in a continuous operation. The
ball, sealed tightly in the socket, has just
enough room for it to roll freely as ink
from the tube flows into the ball socket.
The ball diameter varies from 0.4 mm to
1.4 mm, providing a line thickness from
super fine to super thick. The tip-making
machines are generally Swiss made. The
high-precision Swiss machine MIKRON
is a market leader.
Plastic is generally used for the body of
the pen because it is not only relatively
inexpensive but also lightweight and
corrosion resistant. The body is made
from molded plastic by injection
molding. In this process, plastic resin in
the form of granules is forced through a
heated barrel by either an injecting ram
or a screw rotating inside the heated
barrel. The heat liquefies the resin,
which is injected into a die cast mold,
cooled and removed. Excess plastic is
then scrapped away, and the pieces are
cleaned and sent for the next operation.
Printing the model or company name
and logo on the molded body is done
by what is called the thin film printing
process, where a thin plastic foil
with the imprint of the matter to be
printed is hot-pressed on to the pen
body thus transferring the impression.
These machines use a combination of
pneumatic elements, stepper motors
and sensors. A rubber grip is sometimes
attached near the writing tip of the
body to allow a comfortable grip. The
assembled refill and ballpoint are then
inserted into the molded body of the pen
(made of aluminum or steel in addition
THE ELGI MAGAZINE
31
In early 2000, Newell Rubbermaid, the
world’s largest manufacturer of writing
instruments, acquired Paper Mate, Parker
and Waterman, three of the most famous
names in the evolution of the pen. Newell
went on to create exquisite writing
instruments valued not just for their ease
of writing but also for their elegant quality,
craftsmanship and their superior image.
Tiffany & Co. has been a leading
manufacturer of high-quality ballpoint
pens. Established in New York in 1837 as
a stationery and fancy good store, Tiffany
Landmark
High-End Pens
added jewellery in 1902. Among the company’s range of
accessories is the Tiffany T-Clip retractable pen and pencil
set, in ruthenium with gold-plated accents.
In 1847, Louis-Francois Cartier established his workshop
in Paris. They too crafted superior ballpoint pens, such as
the 1904 Santos de Cartier limited edition, among the fine
line of writing instruments that Cartier produced. Their
pens, incorporating Charm ball tips, feature special logos
like the double C de Cartier logo or the heart-shaped
charm.
Reciprocating air compressors manufactured by Elgi are used extensively by pen
manufacturers
to plastic), either manually or by pneumatically operated long
assembly lines. The rest of the component parts like, pocket
clip, spring and plunger mechanism for retracting the refill are
assembled. Once this is done, the pen is labeled and packaged,
and ready to be shipped out.
As is evident, compressed air plays a key role in the
manufacturing process at various stages. The ball tip machine
itself uses compressed air in air ejectors that move the tiny
tips along in the machine. Air is again used in subsequent
operations till the tips are ready for fitment into the refill. This
fitment, when done on automatic machines, is once again
facilitated by pneumatic elements like piston and cylinders
that fill the cartridge/refill with ink, attach the tip, seal the
32
THE ELGI MAGAZINE
other end with a cap etc. Compressed air is used in the injection
molding process too and also in the hot-press printing machine.
Reciprocating air compressors manufactured by Elgi are used
extensively by pen manufactures. A drier is usually attached to
the compressed air reservoir outlet to remove moisture, while
filters draw out any trapped oil in the air. Rated for continuous
operation under very demanding operating conditions, Elgi
reciprocating compressors have been widely accepted by
the pen industry. Take Cello Pens for example, located in the
union territory of Daman, and the other units under their
group, which is counted among the industry leaders. Elgi
reciprocating air compressors meet their compressed air needs
very adequately operating under demanding conditions. n
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THE ELGI MAGAZINE
33
Pressure Vessels
On a bright summer afternoon in April
28, 1988, Aloha Airlines flight 243 was
cruising under clear blue skies and in
fair weather. The Boeing 737 with 89
passengers on board was on a scheduled
flight from Hilo to Honolulu in Hawaii.
Barely ten minutes into the flight
however, as the plane levelled off at
24000 feet, the pilots heard a loud ‘clap’
followed by a wind noise behind them.
Looking behind they observed that the
cockpit entry door was missing and
there was blue sky where the first-class
ceiling had been. They watched in horror
as a flight attended was swept out of the
cabin through the hole in the fuselage.
The plane began descending rapidly.
Miraculously, though the flight suffered
extensive damage due to the explosive
decompression of the fuselage, the crew
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managed to land safely at Kahului Airport
on Maui. The only fatality was the flight
attendant who was blown out of the
airplane. That event marked a significant
point in the history of aviation, with
far-reaching consequences to aviation
safety policies and procedures.
But what has an airline disaster got
to do with pressure vessels? Plenty,
really, because airplane cabins are
pressure vessels too or rather, pressurecontaining structures. The Aloha
Airline
disaster
illustrates
very
dramatically
the
importance
of
proper design, since the air in the
cabin is pressurized to normal
atmospheric
pressure,
which
is
greater compared to the low pressure
of the thin air outside the fuselage.
So essentially, what is a pressure vessel?
A pressure vessel is a closed container
designed to hold air, gases or liquids at
a pressure substantially different from
the ambient pressure. More specifically,
a pressure vessel is a storage tank or
vessel that has been designed to contain
pressures above one bar (1 kg/cm2.)
Understandably, since the pressure
differential, especially if it is high, is
a safety hazard with the potential for
rupture and explosion, the design,
manufacture, and operation of pressure
vessels are regulated by engineering
authorities backed by government
legislation. Though the definition of a
pressure vessel varies from country to
country, it invariably involves parameters
such as shape, thickness and strength
of its material, its physical properties,
INDUSTRY INSIGHTS
Pressure vessels are able to hold up against internal pressure due to tensile forces
within their walls
and maximum safe operating pressure
and temperature. In India, the standard
commonly used is the ASME Section VIII
Div (1).
Pressure vessels find variety of
applications in both industry and the
private sector, which goes a long way
back in time ever since large pressure
vessels were invented during the
industrial revolution, particularly in
Great Britain, following the invention
of boilers and steam engines. Indeed,
subsequent boiler explosions paved the
way for the establishment of design
and testing standards and a system of
certification. Today, industrial application
of pressure vessels spans a very wide
range – from chemical industry to
cosmetics, from food and beverage to oil
and fuel, from paper and pulp industry
to pharmaceutical and plastics and from
power generation to energy processing
and so on.
Types of Pressure Vessels
Pressure vessels can be classified
according to their dimensions or
according to their end construction.
The former classifies vessels as either
having thin shells or thick shells, the
deciding factor being wall thickness.
More specifically, if the ratio of
thickness to shell diameter is less than
1/10 the vessel is said to be thin shell
and if the ratio is greater than 1/10 it
is said to be a thick shell. Thin shells
are typically used in boilers, tanks and
pipes whereas thick shells are used
in high-pressure cylinders. The latter
classification on the other hand, is based
on the end construction of the pressure
vessel – either open ended or close
ended. A asimple cylinder with a piston
is an example of open-ended vessel
while a pressure cylinder is an example
of a close-ended vessel.
When a vessel is pressurized, pressure
is exerted against its walls. Pressure is
always normal to the surface regardless
of its shape. In case of open-ended
vessels circumferential pressure is
induced whereas in case of close-ended
vessels longitudinal stresses acting on
the ends are also induced in addition to
circumferential stresses. Theoretically, a
pressure vessel can be designed to have
almost any shape, but from a safety
point of view shapes made of sections of
spheres and cylinders are most common.
Thus a common design would be a
cylinder with rounded or semi-elliptical
domed end caps, called dished ends.
Pressure vessels are able to hold up
against internal pressure due to tensile
forces within their walls. The normal
tensile stress in the walls of the vessel is
proportional to the pressure and radius
of the vessel and inversely proportional
to the thickness of its walls. Therefore,
pressure vessels are designed to have
a thickness proportional to its radius
and the inside pressure, and inversely
proportional to the maximum allowed
normal stress of the material of its
walls. The design and certification
of pressure vessels is governed by
international design codes and they are
designed to operate safely at specific
pressures and temperatures, technically
referred to as the ‘Design Pressure’ and
‘Design Temperature’. And to ensure
confirmation, there are a variety of
tests performed on pressure vessel, like
hydrostatic test, burst test, and pressure
cycling.
Process of Manufacturing
Many pressure vessels are made of steel
– low-carbon ductile steel alloyed with
manganese or chrome molybdenum
THE ELGI MAGAZINE
35
that are easily drawn into dished ends
or rolled into cylindrical shapes. To
manufacture a cylindrical pressure
vessel, rolled cylindrical sections are
welded at the seam to form an openended cylinder. Dished ends are then
welded onto the ends to close off the
cylinder and form the vessel. However,
in case of smaller pressure vessels
like domestic LPG cylinders meant to
withstand lower pressures of around
16 bar, the cylindrical section is avoided
altogether. Instead, two elongated
spherical sections deep drawn out of a
circular piece of steel plate are welded
together. The 2.9 mm thick steel plate is
fed through a hydraulic or mechanical
press to stamp out the circular sections.
Sometimes rotating cutting dies are
used to cut out the circles. These are then
fed into the annular ring dies of a deep
drawing press. A bulbous ram then draws
the circular plate section downward
through the curved inner contour of the
ring-die so that the plate wraps around
the bulbous ram, cold-formed to replicate
its shape, looking much like half a
pharmaceutical pill or capsule. The edges
of the capsule are trimmed and one of
them has its edges pressed-in to form a
circumferential dent or recess. Another
piece without the press-in is then placed
over the recessed band to form a lap joint
and the two are welded together using
MIG (metal inert gas) welding. Prior to
that, one section has a hole stamped out
of its bottom and an inside-threaded
neck is welded into the hole to facilitate
attaching the pressure regulator later.
After welding together the two halves, a
circular ring at the bottom to form a base
and a raised steel ring at the top to form
a handle are welded on to the vessel. The
deep drawing and the welding produces
considerable inner stress in the steel,
which is relieved by heat treatment in
a furnace. Various tests follow: Visual or
ultrasonic test to identify poor welding.
These are isolated and send for rewelding. A hydrostatic test, where the
vessels are filled with water and the
pressure raised up to 30 bar, to reveal
any leakages. Next, an air pressure test,
where the vessels pressurized up to 15
bar are immersed in water to reveal
weak spots through escaping air bubbles.
Imperfectly welded or faulty vessels can
result in leakage or rupture failures.
And if the vessels carry poisonous or
flammable gases, leaking vessels pose
potential health and safety hazards
like poisonings, suffocations, fires or
explosion. Similarly, rupture failures
can cause catastrophic damage to life
and property. It is easy to understand
why the safe design, manufacture and
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THE ELGI MAGAZINE
It is easy to understand why
the safe design, manufacture
and testing of pressure vessels
in accordance with appropriate
codes and standards are so
essential
INDUSTRY INSIGHTS
testing of pressure vessels in accordance
with appropriate codes and standards
are so essential. Vessels that come
through the designated tests are then
shot blasted using steel grit to remove
surface dirt, rust and scales. Important
information like type of cylinder, the
service pressure, serial number, date
of manufacture, the manufacture’s
registered code and sometimes the test
pressure are usually stamped on the
cylinder. It is now ready for painting
– a corrosion-resistant primer coat
followed by a top coat of enamel paint.
As against a domestic LPG cylinder,
a typical CNG cylinder is subjected
to more vigorous tests such as,
•
Online ultrasonic testing – to test
soundness of weld joints.
•Hydrostatic testing – water pressure
test
•Air leak testing – carried out 100%
•Batch tests like mechanical testing – to
ensure mechanical properties like yield
strength, hardness etc are according to
specified standards.
•Burst testing – to ascertain volumetric
expansion of the container is within
limits.
•Bonfire testing – should not burst when
tested under specified fire conditions
with direct impingement of fire on the
LPG filled container
And auto LPG containers are subjected
to these additional tests:
•Crash test – should not leak when it is
subjected to crash/collision
•Fatigue test – should not fail when
subjected to successive reversals
of upper & lower cyclic pressures
developed by hydro pneumatic pumps.
•Radiography test – random checking to
test weld joints.
•Vibration test
Thick-walled Pressure Vessels
Let’s now look at thick-walled vessels
meant to carry higher pressures of 20
bar or more and used as joint-less CNG
cylinders, industrial cylinders and all
high pressure cylinders. A typical thickshell pressure vessel for containing
industrial gases will have neither rolled
cylindrical sections nor dished ends.
Rather, its manufacture begins with
segments cut off from seamless tubes
of thickness ranging from 10 mm to 30
mm or more depending on the service
pressure of the intended vessel. The ends
of the tubular sections are then hotformed and fused shut, much like how
a potter might close the open mouth of
a pot spinning on his wheel. Indeed, this
metal forming process known as ‘Hot
Thick-walled vessels are meant to carry higher
pressures of 20 bar or more and used as joint-less CNG
cylinders, industrial cylinders and all high
pressure cylinders
Spinning’ is derived from the ancient
Egyptian art of a potting wheel. The
rapidly rotating manually operated
potter’s wheel, known to be in use from
as early as 3000 BC, provided the basis for
the art of metal spinning. But this process
is much more intricate, because pressure
vessels are made of thick steel, not clay.
The process begins with cutting the
required length of seamless tube, then
heating one end in a furnace or induction
heater to nearly 11000C, to get the metal
to a pliable state. This is also important
in order to reduce possible stress points,
which would occur if the end of the
tube is not hot enough. The tube is
then clamped into the chuck of a CNCcontrolled heavy-duty spin-forming
machine with the hot end protruding
out of the headstock. As the headstock
rotates, the tube is spun at the required
forming speed. The forming process
begins when the forming roller attached
to the rotary forming head moves toward
the hot tube-end. Simultaneously, an
oxy-acetylene flame is ignited that heats
the tube-end further, maintaining the
temperature required for hot forming.
The forming roller is programmed to
make a series of sweeping motions,
progressively forming the metal. The
roller first touches the hot, spinning
tube externally near the edge and moves
out in an arc towards the longitudinal
axis of the tube. As the forming roller
rotates around the tube end, it forms
the tube toward its center, reducing its
diameter at the end and tending to close
the mouth. The in-feed is advanced in
small increments as the forming roller
is moved back and forth forming the
end around until the tube-end is closed
and nearly fused together. At this point,
another high intensity oxy-acetylene
flame is ignited just in front of the closed
tube end. This blows a small hole at the
apex of the rounded end blowing off
trapped scales and other impurities.
This is called centre cutting. The roller
head then makes a couple of final
passes over the tube-end to finally fuse
the end closed. The roller head is then
rapidly backed away so that the formed
tube can be ejected. Top-of-the-line
spinning machines have programmable
operations in CNC mode, or even in
combination of manual playback with
THE ELGI MAGAZINE
37
image : abedigroup.com
image : abedigroup.com
image : abedigroup.com
An oxy-acetylene flame is ignited that heats the tube-end. The ends of the tubular
sections are then hot-formed and fused shut, much like how a potter might close
the open mouth of a pot spinning on his wheel
CNC control. In the playback mode,
the first part is run manually by the
operator via a joystick. This part is
spun at relatively small feed-rate
speeds before CNC control takes over.
Necking
This is the operation of forming the
free end of the tube along with a neck,
on which a pressure regulator or a shut
off valve can be attached later. This end,
therefore, is not completely closed since
either a threaded adapter is welded
in place or the neck itself is bored and
threaded to receive the threaded valve.
As in the previous case, in a series of
sweeps of the forming roller, the free
end too is progressively shaped with
the difference that a neck is formed at
the apex of the rounded end. The same
forming roller may be used for both
the ends or in some cases separate
rollers perform the operation of bottom
closing and necking-in. Testing of
thick-shell vessels are much more
stringent than thin-shells. The finished
vessels are permanently stamped with
serial number, test date, test pressure
specification, water capacity etc.
Random and batch samples are
collected regularly by inspectors
from the Chief Controller of Explosive
(CCOE) for testing and approval.
Samples also need to be certified by an
independent board namely, Bureau of
Indian Standards (BIS). These agencies
not only have the authority to issue
licenses to manufacturers but also
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work in close coordination with them
at various stages of production. They
exchange
information
constantly
and overview the production process
to ensure that the stringent quality
standards specified are maintained.
Compressed air is used at various
points in the manufacturing process
of pressure vessels. Deep drawing
presses utilize compressed air to
actuate certain pneumatic components.
Hydrostatic and pressure testing of
vessels employ compressed air. MIG
MIG Welding
welding electrodes too are advanced and
retracted using pneumatic actuators.
Shot blasting is another area as also
spray-painting of the finished vessels.
There are number of manufacturers
in India who produce domestic LPG
cylinders, industrial gas cylinders and
auto LPG tanks among other pressure
vessels, catering to both Indian and
foreign markets. Elgi compressors have
been meeting the compressed air needs
of this industrial segment for number of
years.
n
Metal inert gas (MIG) welding differs from normal arc welding in that it
is a semi-automatic or automatic arc welding process in which instead
of a welding rod, a continuous and consumable wire electrode from a
spool surrounded by a shielding gas are fed through a welding gun. The
shielding gas forms what is called the arc plasma, stabilizes the arc on
the metal being welded, shields the arc and molten weld pool, and allows
smooth transfer of metal from the weld wire to the molten weld pool. A
constant DC power source is most commonly used, but AC supply too is
sometimes employed. Originally developed for welding aluminium and
other non-ferrous materials in the 1940s, MIG welding was soon applied
to steels because it is considerably faster compared to other welding
processes. The cost of inert gas though became a limiting factor until
several years later, when semi-inert gases such as carbon dioxide began
to be used. Further developments during the 1950s and 1960s made the
process more versatile and as a result, it became a common industrial
process. Today, MIG welding is the most widely used industrial welding
process, preferred for its versatility, speed, high deposition rate and the
relative ease of adapting the process to automation.
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THE ELGI MAGAZINE
39
Ceramic
40
THE ELGI MAGAZINE
INDUSTRY INSIGHTS
Ceramic and Sanskrit make strange
bedfellows. Yet, ceramic does, in fact,
have some kinship with Sanskrit. The
word ‘ceramic’ comes from the Greek
word ‘keramos’ meaning pottery, and
it is related to an old Sanskrit root,
meaning ‘to burn’ that also carries the
primary meaning of ‘burnt stuff.’ It all
began when ancient cultures discovered
that clay lining of their primitive ovens
and stoves turned hard and strong over
time. Subsequently, they discovered that
firing clay tiles at high temperatures in
a kiln made them stronger and more
water-resistant. Before long, they
invented new uses for the tiles. Though
ancient Egyptians are credited with the
discovery of clay tiles, other civilizations
too are known to have used thin squares
of fired clay as decorative elements in
their architecture. Buildings in ancient
Tiles
A journey from the bowels of the earth
to floors and façades
Mesopotamian cities for example, were
fronted with unglazed terra cotta and
colorful decorative tiles. As early as in
3000 BC, Mesopotamian city-states
like Uruk and Babylon had started
manufacturing tiles glazed with cobalt
ore to produce brilliant blue tiles that
were used for cladding the walls of
temples, tombs and palaces. Egyptian
artists created turquoise inlaid tiles that
were used to line the inside of the Step
Pyramid for the Pharaoh Djoser in 2700
BC. While ancient Greeks and Romans
used ceramics for floors and roofs, in
medieval Europe, tiles were generally
reserved for the floors of churches. But
the Byzantine Empire used tiles more
artistically, and created expressive
mosaic patterns and murals employing
ceramic tile, pieces of glass, and stone. In
the east, China’s Shang Dynasty began
using tiles as a roofing material and to
decorate the walls of tombs. The Chinese
also used a white clay called kaolin to
develop the white-hued and durable
ceramic known as porcelain.
From Regions to Religion
The story continues when you shift
from regions to religion: Islam has
played an important role too in the
spread and evolution of ceramic tiles.
Beginning in the seventh century BC,
ceramic tiles have played a prominent
role in Muslim culture and society, and
were used extensively in a wide swath
of land extending from Morocco in the
West to India in the East, embellishing
walls and floors of mosques and palaces
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41
Europe has seen some important
landmarks in the history of
ceramic tiles: The tile mosaics of
Spain and Portugal, the floor tiles
of renaissance Italy, the faiences of
Antwerp, and the ceramic tiles of
Germany
in complex geometric patterns. Artistic
use of ceramic tiles scaled new heights
during the early Islamic period for,
many methods of tile decoration were
brought to perfection in Persia by early
Muslim artisans. In later centuries,
influenced by the Roman and Greek use
of clay tiles for roofing, and the artistic
use of tiles by Muslims, European
countries such as France, Spain and Italy
started using tiles in the construction
of houses and other buildings. Indeed,
from mid 12th century onwards, Europe
has seen some important landmarks
in the history of ceramic tiles: The tile
mosaics of Spain and Portugal, the floor
tiles of renaissance Italy, the faiences
of Antwerp, and the ceramic tiles of
Germany. By the 16th century, Italian tile
makers were in high demand especially
in the affluent Spanish kingdom. Later,
ceramic tiles were manufactured in
virtually every major European country
and in the US. By early twentieth
century, ceramic and other tiles began to
be manufactured on an industrial scale.
New
inventions
led
to
faster
manufacturing and more refined
and durable products. Today, tile
manufacturing is a highly automated
process all over the world.
Sitting snugly on the floors and facades of
buildings across the globe in the present
day world, the humble ceramic tile has
indeed traversed a long and colourful
journey from the earliest cradles of
civilization to the 21st century. While
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Clockwise from left: feldspar quartz, quartz, green clay-illite, talc, kaolite-clay, calcite
that journey is fascinating, another
journey from the raw-material stage to
the finished tile is no less engrossing.
From Mother Earth
That journey begins with the raw
materials quarried from mother earth:
Potash, various kinds of clays like
white clay, illitic and kaolinitic clays,
soda, qartz, talc, feldspar, sand, and
natural rock-forming minerals like
calcite and dolomite. After quarrying,
these materials are refined to remove
impurities and crushed to break down
lumps to smaller, uniform sizes. Hard,
lumpy materials are pulverized and
classified according to particle size.
Primary crushers, either jaw crusher or
gyratory crushers, reduce large lumps
of material. Secondary crushing reduces
smaller lumps to particles. Hammer or
Muller mills are often used. A Muller
mill uses steel wheels in a slow-rotating
shallow pan, while a hammer mill uses
rapidly moving steel hammers to crush
the material, ready to be shipped
Once the raw materials reach a tile
factory, they are stored in holding
areas. Manufacturers create their own
composition of the various types of clays
and other ingredients and these recipes
are sometimes patented and closely
guarded.
INDUSTRY INSIGHTS
The manufacturing process begins
with the mixing of raw materials in
specific proportions by weight. This is
achieved by one of two processes: Batch
mixing, where individual ingredients
are weighed in batches and loaded
into a holding tank; and conveyor
mixing, where different materials from
individual compartments are conveyed
through swiftly moving belts into a
holding tank. The specified mix of raw
materials is achieved by varying the
speed of the conveyor belts that feed
a master conveyor. This conveyor then
dumps the raw material mix into a
storage tank, from where it is fed into a
mixing drum, again through a conveyor
belt system. In the case of batch mixing
however, raw materials from the holding
tank are conveyed to the mixing drum
through a single conveyor belt.
The mixing drum, also called a ball mill, is
a large horizontal drum rotating at slow
speed. Once the mix of raw materials is
loaded into it, a predetermined quantity
of water is then added. The drum also
carries sufficient quantities of ceramic
pellets to help in grinding the various
raw materials. This process of grinding
all the raw materials together with
water is called ‘wet milling’ and can take
up to six hours, during which the pellets,
raw materials and water all tumble
together inside the drum to produce
a slurry of uniform consistency. This
smooth slurry is then conveyed through
sloping channels into underground
tanks. A binder is then added to the
slurry – to help in the final binding of
the raw materials – and the whole mix
is then churned continuously for hours,
Glazed Tiles
Raw materials
Dry milling
Wet milling and
spray drying
Extrusion
Dust pressing
Rustic tiles
Wall tiles
Floor tiles
Porcelain tiles
Fleur gases
Chimney
Hot gases
sprayed
slurry
spray dried powder
Ceramic tiles come in two basic constructions: glazed and unglazed. The
difference is quite simple. A glazed tile is a ceramic tile to which a glaze
has been applied. To produce a glazed tile, the glaze – colored glass in
liquid form – is applied to the hard tiles after the first firing and then,
after the glaze is painted or sprayed on, the tiles are fired once again at
a temperature, which varies depending on the type of clay used and the
glaze applied. The second firing at high temperatures causes a chemical
reaction, which makes the glaze vitrify, essentially turning it into hardened
glass. The liquid glass coating is what creates the texture, design and
colour of a glazed tile. The resulting tile is not only impervious to water
and stains but is also scratch and fire resistant. Glazing also imparts
an attractive, glossy look. A wide variety of colours and designs can be
created with glaze, with finishes ranging from extremely glossy to matte.
The colours in the glaze are obtained from various minerals, such as zinc,
mercury, copper, gold and silver. Glazing therefore allows ceramic tiles to
be offered in unlimited colours and designs. Glazed tiles though are prone
to wear and tear, unlike unglazed ceramic tiles.
THE ELGI MAGAZINE
43
using motor-driven paddles that dip
into the underground tanks, to produce
a homogenous slurry ready for the next
process.
That process, called ‘spray drying,’
involves drying the slurry to produce a fine
powder. It is achieved by first pumping
the slurry from the underground tanks
into huge, stainless-steel drying drums.
The slurry is sprayed up from nozzles
at the bottom of the drum. A fine spray
shoots up to meet air as hot as 7000C
blown down from a blower and heater
at the top. The sprayed slurry is rapidly
dried and falls back to the bottom of the
tank in the form of tiny granules – due to
residual moisture.
This atomized powder is drawn out
through the bottom of the drum and
conveyer belts then transport it to
storage silos. It is now ready for the next
stage of molding where the tile actually
takes shape.
Dust Compression
Storage silos are located at a height,
facilitating the powder to flow down
by gravity through large pipes into a
distributor attached to a hydraulic press.
Measured quantities of the powder
image: lifeofanarchitect.com
The Morbi Connection
Morbi, located in the Saurashtra region
of Gujarat, has the distinction of being
the hub of ceramic tile manufacturing in
India. Here are some highlights:
• Home to 600 odd manufacturing
units.
• Cumulative investment of approx Rs.
5000 Crores.
• Manufactures more than 70% of
total ceramic production in India.
• Total installed capacity of 1.8 million
square feet tiles per day.
• Gives direct employment to 85000
people.
• Supply of LPG through pipelines set
up by the government is a big boost.
• Leading ceramic companies like HR
Johnson, Asian tiles and Somani
outsource their requirements from
Morbi.
• Close vicinity of Morbi to major ports
like Kandla and Mundra reduces
transportation costs substantially.
image: lifeofanarchitect.com
image: lifeofanarchitect.com
from left: compression and puff of compressed air, application of glaze, drying, kiln
are released by the distributor and
transferred evenly into a flat mold. A
puff of compressed air is used to blow
away excess powder from around the
mold. The combination of high pressure
from the heavy-duty, fully automatic
hydraulic press and residual moisture
turns the compressed powder into a solid
mass. This produces a hard, dense and
homogenous tile with very low porosity
known as “Vitrified” tile. The formed tiles
are then transported through conveyor
belts into a dryer to remove most of the
remaining moisture.
The dried tiles are next transported
through conveyor belts to the design
section where multiple rubber rollers
carrying designs and smeared with
44
THE ELGI MAGAZINE
chemical dyes form imprints on the
tile face as they pass under them.
The soluble dyes penetrate the top
layer of the tile, making them integral
with the rest of the material. After a
brief period of air-drying, conveyor belts
transport the tiles to kilns where they
are stacked closely. The stacked tiles then
move continuously through different
temperature zones of a kiln, traversing
a distance of up to two hundred metres
or more. Exposed to temperatures of up
to 12000C or more, the tiles crystallize,
making them very hard and durable.
They gain their ultimate hardness after
this process.
Kiln-fired tiles are then carried on
conveyor belts, and moved across a
continuous band of polishers, where
each tile is exposed sequentially
to fast rotating polishing heads
carrying abrasive stones that change
progressively from hard to fine to super
fine. As the tiles pass under the band of
high-speed polishing heads, a mixture of
water and compressed air is constantly
fed between the tile surface and the
stones to provide adequate lubrication.
This produces a smooth, glossy surface
on the tile.
Nano Polishing
In more expensive tiles, a final round
of polishing using a chemical fluid
known in the industry as ‘Nano-liquid”
produces a highly glossy, mirror-like
finish. A blast of hot compressed air
INDUSTRY INSIGHTS
Industry Highlights
The Indian tile industry is
divided into organized and
unorganized sector.
image: lifeofanarchitect.com
directed on to the wet, pre-polished tiles
dries them swiftly, and readies them for
“Nano polishing” without stoppage. This
specially formulated product contains
functional nano particles made of silicon
and a solvent. The thin layer of liquid
silica fills the micro (nano) pores on the
tiles’ surface and gives them not just a
mirror finish but also makes them water
and dust repellent and anti-bacterial too.
Just a few drops of the nano liquid is all it
takes to create a distinctly superior finish
and value addition to the finished tile.
Along with copious amounts of water,
compressed air plays a very important
role in the manufacturing process
of tiles. Apart from press-forming,
quick-drying and grinding, compressed
image: lifeofanarchitect.com
air also actuates various pneumatic
devices that facilitate shifting and
movement of tiles including tile
movements in the conveyor belt system.
From established big names in the
industry to mid-range group companies
to a vast clientele in the unorganised
sector, Elgi air compressors have been
catering efficiently to the needs of
this fascinating and fast-growing
industry.
The CASA group of tile industries is
typical. With a product range spreading
across wide segments, CASA uses Elgi’s
oil-less screw air compressors to meet
their compressed air demands at various
stages of production in their various
plants. n
The organized sector is made
up of roughly three dozen
manufacturers, and its current
size is about Rs 2625 Crores.
The unorganized sector
accounts for 70% of the total
industry, bearing testimony
to the attractive returns from
this sector. The size of the
unorganized sector stands
roughly at Rs 6125 Crores.
Total annual production in
India stands at 500 million
square meters, while the world
production stands at 7000
million square meters.
India ranks among the top 3
countries in the world in terms
of volume of production.
THE ELGI MAGAZINE
45
Air intake
Separation
Nitrogen
filling
Preliminary
Purification
Crude Argon
Separation
Compression
Preliminary
Cooling
Air
Separation
Oxygen
filling
Cryogenic Air Separation
You are familiar with the ubiquitous LPG
cylinders in households and hotels. You
might also have seen somewhat long,
slender cylinders in many other places,
notably in hospitals and spas, workshops
and garages or on factory floors. Ever
wondered what these cylinders contain?
What ever gas they might hold, one
thing is certain; most are derived from a
substance that is omnipresent, existing
everywhere on the planet though you
never see it. An invisible substance that
has no smell or taste, mass or matter,
colour or weight and yet, is composed of
a variety of individual elements. What’s
this enigmatic substance? We are talking
of that lungful of air you just took. And
what are the elements it is made up
of? Air is 78% nitrogen, 21% oxygen,
less than one percent argon and some
trace gases like carbon dioxide, helium
and neon. That 21% oxygen not only
supports all life on the planet, but also
has numerous commercial and other
uses. While myriad chemical reactions
and oxy-acetylene cutting flames form
some of its industrial applications, it’s
46
THE ELGI MAGAZINE
a vital element in hospitals and health
spas too. Similarly, nitrogen has a slew
of applications in industries, in food
packaging and in automobile tyre
inflation. Argon has its own specialised
uses most commonly in welding. To
obtain these gases however, air needs
to be split into its constituent elements.
That process, called air separation, is
achieved in a variety of ways such as,
• Air Adsorption
• Polymer Membrane
• Cryogenic Distillation
Adsorption is a process in which atoms
or molecules of gases or liquids adhere
to the surface of a substance, such as a
solid. The molecules are attracted to the
surface but do not enter the solid’s inner
spaces as in absorption. The accumulated
molecules or atoms create a film on
the surface of the solid adsorbent. The
substances giving off the atoms or
molecules are called the adsorbate. In
a drinking water filter for example, the
water is the adsorbate while carbon
cartridges that adsorb contaminants is
the adsorbent. This process differs from
absorption, in which a fluid permeates a
solid, like ink permeating blotting paper.
Adsorption results from electrostatic
attraction as well as from surface
tension, which is a consequence of
bonding of atoms due to surface energy.
This phenomenon is found in many
natural physical, biological, and chemical
systems, and is widely used in industrial
applications.
Most
commonly
used
industrial
adsorbents are silica gel, activated
carbon, and graphite. These are used
usually in the form of spherical pellets,
rods, or moldings. In air separation
for example, highly porous activated
INDUSTRY INSIGHTS
Carbon
molecular
sieve
Off gas
N2
Desorption (1 bar)
Adsorption (8 bar)
Nitrogen production
02
Swing adsorption
process of air separation
charcoal pellet is largely employed as
the adsorbent in which the constituent
gases, or adsorbates, are selectively
transferred from the air to the surface of
insoluble, rigid particles of the charcoal.
Activated charcoal is simply coal heated
to nearly 4000C to release unwanted byproducts, then “activated” by exposing it
to an oxidizing agent, usually steam or
carbon dioxide at high temperatures that
creates the essential micro porosity.
Let’s now look at the adsorption process
in some detail. This process is based on
the principle that under pressure, gas
molecules tend to be attracted more
readily to solid surfaces, or “adsorbed.”
The higher the pressure, more the
gas that is adsorbed, and when the
pressure is reduced, the gas is released,
or desorbed. PSA process is used to
separate constituent gases in air because
different gases tend to be attracted to
different adsorbents at rates depending
upon pressure and temperature. When
air under pressure, for example, is passed
through a vessel containing a bed of
adsorbent material such as activated
carbon and alumina that attracts oxygen
more strongly than it does nitrogen, part
or all of the oxygen will be adsorbed by the
bed, and the output gas from the vessel
will be rich in nitrogen. When the bed
reaches its capacity to adsorb any more
oxygen, it is regenerated by reducing the
pressure, thereby releasing the adsorbed
oxygen. It is then ready for another cycle
of operation. In practice, two such vessels
are employed. Thus, during adsorption
in one vessel the other is totally
regenerated just by depressurizing it to
ambient pressure, that is, the oxygenenriched gas is vented to the atmosphere.
Using a standby adsorbent vessel allows
near-continuous production of the
required gas. It also permits pressure
equalization, where the gas leaving the
vessel being de-pressured is used to
partially re-pressurize the standby vessel.
This common industrial practice results
in significant energy savings. Air filters
and driers at various stages ensure that
the air being fed into the vessels is free
of impurities and moisture. This process
also requires constant temperature, close
to ambient, and therefore air chillers
are employed to take away the heat of
compression generated while air is first
compressed before being fed into the
system.
The process automatically directs
the incoming air in to either of two
vessels each running for a few minutes
through an automatic change over
valve. As explained, at the adsorption
stage, oxygen molecules diffuse into
the pore structure of the adsorbent
material while the nitrogen molecules
are allowed to travel through the vessel.
At the regeneration stage, the adsorbed
oxygen is released from the adsorbent
and vented into the atmosphere. The
process is then automatically repeated,
wherein adsorption process is switched
over to the second tower and the first one
is regenerated. PSA nitrogen generator
plants produce nitrogen of high purity of
up to 99.99 %.
Polymer Membrane process on the other
hand uses different diffusion speeds
of the constituent gases in air through
a polymer membrane. Clean, dry
compressed air at the required pressure
is led through a membrane module as
shown in Fig 1. Component gases with
higher diffusion speeds like oxygen and
carbon dioxide penetrate the polymer
membrane fibres quicker, producing
an end gas that is richer in the left over
nitrogen. Purity of nitrogen depends on
the flow speed through the membrane
module and can be up to 93 - 99.5 % or
more.
Nonporous polymeric membranes that
are glassy are most commonly used. The
gases are separated due to their different
solubility and diffusivity in polymers in
accordance with their molecular size.
Gases with smaller molecules penetrate
the polymer chains faster resulting
in higher diffusivity. Thus, hydrogen
passes four times faster than oxygen
leading to higher separation efficiency
for hydrogen. In special cases, in order to
separate a particular gas, other materials
are also used. For example, Palladium
membranes permit movement solely of
hydrogen.
Even though the PSA and membrane
are relatively simple processes, the third
process of cryogenic distillation is the
most commonly used for air separation.
This method, pioneered by Dr. Carl
von Linde in the early 20th century, is
commonly used today to produce high
purity gases. The process relies on the
fact that different gases have different
condensation temperatures.
Cryogenic distillation employed for
separation of air into its constituent
gases at high purity essentially works
at very low distillation temperatures
and therefore requires specialised
refrigeration
equipments. The air
also has to be completely free of
impurities and moisture for effective
cryogenic distillation, since water and
Polymer Membrane
process of air separation
THE ELGI MAGAZINE
47
carbon dioxide as well as other minor
constituents of air can freeze in the
cryogenic equipment. Atmospheric air
is pre-filtered to remove dust and other
suspended matter, and compressed
to a pressure between 5 and 10 bar.
Since the compression heats up the air
substantially, it is cooled by a cooler to
ambient temperatures. This also helps
in the precipitation and removal of
some ambient moisture. The process
air is now passed through a molecular
sieve bed, which removes any remaining
water vapour, as well as carbon dioxide,
which would freeze in the cryogenic
equipment. The molecular sieve is
also designed to remove any gaseous
hydrocarbons from the air. Next the air
is cooled to very low temperature by the
refrigeration equipments. At various low
temperatures different gases condense
out of the air and is taken out as liquid
gases. The process is explained below in
some detail.
Pre-filtered and compressed air from
an air receiver is passed through a
heat exchanger to bring down its
temperature to about 10°C. Next,
different stages of filtration clean
the air further and also remove more
condensate. Then a coalescing filter acts
as a gravity filter and finally an adsorber
filled with activated carbon removes
any residual hydrocarbons. At this stage,
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THE ELGI MAGAZINE
the air passes through a thermal swing
adsorber in order to remove carbon
dioxide, any residual water vapour and
remnant hydrocarbons. This completes
the air purification process. From here,
the process air enters the chiller plant
where it is rapidly cooled to -165°C.
This also freezes out any remaining
carbon dioxide. The air then enters the
distillation column. This comprises a
liquid distributor at the top, several
layers of structured packing with liquid
redistributors and a bottom reservoir
to collect the liquid flowing down. Pure
nitrogen is separated at the top of the
column and oxygen enriched liquid
collects at the bottom.
This liquid then passes to the condenser
by means of a Joule-Thomson expansion
valve, which flushes off some of the
liquid as vapour and cools the remaining
liquid. This sub-cooled liquid also
condenses some of the pure nitrogen gas
coming off the top of the column. Part of
the condensed nitrogen is re-admitted
into the distillation column to ensure
purity, and the remaining is stored in
a storage tank. Uncondensed nitrogen
passes through the main heat exchanger
and becomes the end gas delivered to
consumers.
The cryogenic process is capable of
producing very pure end gases; and
is commonly used to produce liquid
nitrogen, oxygen and argon. The highest
obtainable level of purity is generally
99.99%
obtained
by
employing
cryogenic temperatures as low as -173°C.
Cryogenic air separation plants have
proven themselves throughout the
world for number of years.
Gases produced in air separation
plants are either used for a particular
application in the same industrial unit or
may be delivered to consumers through
local pipelines or regional network of gas
cylinders in either liquid form, through
cryogenic transportation, or as highpressure gas in cylinders for various
industrial applications like welding, gas
cutting or to hospitals.
Elgi supplies specialised air compressors
for air separation to equipment
manufacturers. For instance, Elgi
is in association with Airox Nigen
Equipments
of
Gurgaon
who
manufacture air separation plants
among other things. Centrifugal,
reciprocating and screw compressors
from Elgi form part of their air separation
plants. Elgi‘s conventional reciprocating
and
oil-free
piston
compressors,
lubricated screw compressors, oil-free
screw compressors and centrifugal
compressors are mostly used in this
segment.
n
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THE ELGI MAGAZINE
49
The
Odyssey
from
Parchment
to Paper
Revealed: The art and science of papermaking
Gather fibres from the barks of trees, remnants of hemp, rags of cloth and pieces of fishing nets. Add water and
pound the lot together with a wooden mallet until a sludge forms. Strain the gooey mix through a cloth sieve
attached to a frame. Sun-dry what’s left on the sieve… No, this is not a formula for a witch’s brew. So what do
you get from this bizarre recipe? Hold your breath…you’ve just made paper! And the recipe was created by early
man. Beginning with cave walls, then clay tablets and parchment, early humans have experimented with various
means to give expression to their imagination, creativity and passion and to tell stories from their daily lives.
Although the origin of paper is lost to the
hazy past, early Chinese history stakes
claim to its invention. According to their
historical records, Ts’ai Lun, a scribe
of the Imperial Han Court, presented
the emperor with his invention of
papermaking in AD 105, creating paper
from a slurry of mulberry fibres in
50
THE ELGI MAGAZINE
water. Another archaeological record,
however, places the actual invention of
papermaking some 200 years earlier –
during the period of Emperor Wu who
reigned between 140 BC and 86 BC.
Nevertheless, Ts’ai Lun has been given
the place of honour in Chinese history
for his role in developing a material that
revolutionized not just the history of
written communication but his country
as well.
The secret of papermaking wasn’t
confined to china for long. From the 3rd
century this secret art began to creep
out, first to Vietnam and then Tibet. It
The word “paper” comes from papyrus,
ancient Greek for the marsh grass called
Cyperus papyrus
reached Korea in the 4th century and
was introduced to Japan in the 6th.
Over time, papermakers made their
way further west through the Muslim
world, to places like Baghdad, Damascus
and Cairo. It was also stolen during
subsequent battles, and was adapted to
suit other regions where it spread – to
most of Asia and through the Islamic
world to medieval Europe. For example,
paper truly made its push westward in
751 AD when the Tang Dynasty was at
war with the Islamic world. During a
battle on the banks of the Tarus River,
Islamic warriors captured a Chinese
caravan, which was carrying several
papermaking experts. They were caught
and spirited away to Samarkand, which
soon became a great centre for paper
production. They began with a recipe of
fermented cotton and linen rags – and a
flourishing trade soon developed around
the trading of old rags. Depending
on the region, paper also began to be
made using fibres derived from various
indigenous plants, like mulberry, cotton,
banana, and bamboo.
And so it spread, forming an inalienable
part of human life ever since. Paper truly
has a rich and colourful history spanning
across the world’s geography and its
cultures, storing records of history, of
creative outpourings, of inventions and
events and so on, so that we may share
and learn from them, offering us insights
into humanity’s relentless imagination,
creativity and even folly.
How did paper get its name? The word
“paper” comes from papyrus, ancient
Greek for the marsh grass called Cyperus
papyrus. Five thousand years ago in
the Nile River Valley, the Egyptians cut
thin strips from the plant’s stem and
softened them in the muddy waters of
the Nile. These strips were then lightly
woven to form a kind of mat, which was
then pounded into a thin sheet and sun
dried. The resulting sheets made an ideal
writing medium.
A Simple Overview
Today, papermaking begins with trees
as the raw material, although many
non-woody plants can be used too, that
include cotton, wheat straw, sugar cane
waste or bagasse, flax and bamboo.
Cotton is often used to produce high
quality papers. However, nearly 95%
of the raw material for papermaking
comes from trees, both soft and hard
wood. The west uses mostly softwood
like spruce, pine, and fir while hardwood
is used mostly in the east from trees like
eucalyptus and Casuarina. Why trees are
so abundantly used for papermaking
is because of the cellulose fibre in the
wood. Wood essentially consists of
THE ELGI MAGAZINE
51
cellulose fibres bonded together with
lignin (natural glue that holds the wood
fibres together), along with sugars, resins
and other organic compounds. Roughly,
about 40-50% of the tree consists of
cellulose suitable for papermaking,
depending on the species. Therefore,
separating the cellulose from lignin and
other impurities in wood forms the first
step in papermaking: a process called
pulping, which produces a soft, fibrous
substance called paper pulp. Whether
the raw material used is wood or other
non-woody plant matter, pulping is a
crucial process. Pulp is primarily formed
from one of two methods: mechanical
and chemical. Mechanical pulping is
done in several ways, all based on the
same principle: Grinding or chopping the
wood, then treating the resultant wood
chips to a thermo mechanical process in
large steam-heated refiners where the
chips are squeezed and made into fibres
between counter-rotating steel discs to
separate the cellulose fibres from lignin
and other substances. While grinding
alone can produce pulp, steam and
chemicals aid in the process. Even though
mechanical pulping is very efficient, and
can convert over 90% of the wood into
pulp, the resulting pulp contains a high
proportion of lignin, causing the resultant
paper to turn yellow or brown with age
or when exposed to sunlight. The fibres
also tend to be short and stiff, reducing
the mechanical strength of the paper.
Mechanical pulping is therefore limited
to producing pulp meant for packaging,
newsprint, and other low-strength
applications. Sometimes mechanical
pulp is blended with chemical pulp to
produce paper that is both economical
and has reasonable strength and colour
properties. Chemical pulping, on the
other hand, uses chemicals, heat, and
pressure to dissolve the lignin in the
52
THE ELGI MAGAZINE
wood, and free the cellulose fibres. The
wood and chemicals are cooked in a
digester to remove the sugars, about 9095% of the lignin, and other substances.
The waste from the digester is known
as “black liquor,” and it’s often burned at
the paper mill as an energy source.
Pulp from the digester is brown in colour
and to produce white paper, pulp needs
to be bleached. But first it is moved
through a series of washers and screens,
in preparation for bleaching. It is then
diluted and bleached in a five-stage
process in order to achieve a high level
of whiteness. The bleached, wet pulp is
now ready for its final processing into
paper. To turn pulp into paper, the pulp
is pumped into huge, fully automated
machines that have an endless moving
belt of woven nylon mesh. The pulp is
highly diluted with water (sometimes up
to 99%), and the mixture is sprayed onto
the moving mesh screen through a wide
and narrow slit of what is called a flow
spreader to deposit a soggy web of fibres
on the fast moving mesh. As the water
drains through, the fibres settle to form
a sheet. The sheet then goes through
several
steam-heated
mechanical
and vacuum processes, through what
are called squeeze rollers, to dewater,
compact, and dry it. The steam-heated
dryers remove up to of 94 percent of the
water. The sheet, resting on the mesh
and moving at a speed of up to 1000 feet
per minute, is then sent through a final
round of heated rollers to squeeze out
any remaining moisture and compress
the mat into a seamless length of paper.
The paper sheet can be quite large, as
wide as 10 feet and endless in length.
Predetermined lengths of these sheets
are then slit off and wrapped in to rolls
that weigh as much as a few tons, and
are finally ready for shipping.
That is a simple overview of the
whole process. But to understand the
significantly more complicated process
Nearly 95% of the raw material for papermaking comes
from trees, both soft and hard wood
Debarked logs
Wood chips
Sodium hydroxide
and Sodium sulphide
In the mechanical process, logs
are ground into pulp
In the chemical proces, wood chips are
cooked in a chemical solution and boiled until
pulp remains
Beater
After the pulp has been filtered, it is beaten.
Various filler materials are added
of modern papermaking, let’s get into
some interesting details.
Preparing the Raw Material
Wood forms the raw material for nearly
half of the fibre used for paper making
today. Many paper mills have their own
captive plantations for harvesting wood.
Cellulose fibres in the pulp of coniferous
“softwood” trees such as spruce and fir are
longer and therefore make for stronger
paper. Deciduous “hardwood” trees such
as eucalyptus and casuarinas, have
shorter fibres and are ideal for making
paper meant for newsprint. Apart from
this, wood fibre from sawmills, recycled
newspaper, stems of fibrous plants like
bamboo, sugarcane waste or bagasse,
palm oil waste, straw, flax, and even
recycled cloth are used extensively to
produce paper pulp. Cotton and linen
rags are used too to make fine-grade
papers. The rags are usually cuttings and
waste from textile and garment mills,
which are cut and cleaned, boiled, and
beaten before being cooked.
In a modern paper mill using wood as a
raw material, logs are received from the
forest or the plantation in the wood yard.
Here, debarking machines remove the
bark from the logs, which are then taken
to a storage yard. In the mechanical
process of pulping, de-barked logs are
then sent to grinders, which break
the wood down into pulp by pressing
it between huge revolving slabs. In
purely mechanical pulping, mechanical
abrasion separates cellulose fibres from
the lignin that holds them together. This
process however does not remove the
lignin completely. So the paper would
turn yellow as it ages and is therefore
used generally for newspapers and other
non-permanent types of paper.
In the chemical process, de-barked logs
are sent to a chipper where the logs are
broken down swiftly into small chips,
which are then deposited on a chip yard.
Wood chips are then cooked in a chemical
solution called “white liquor.” This is
done in huge vats known as digesters.
The chips are fed into the digester, and
then boiled at high pressure in the
chemical solution. The objective here is
to dissolve the lignin present between
the wood fibres, which form the actual
cellulose pulp. Exposed to chemical
action with white liquor and steam in
the pressure vessel of the batch digester
(so called because chips are loaded in
batches, rather than continuously,)
with controlled temperature, pressure
and cooking time, the lignin inside the
cell walls of the wood is broken down
and dissolves producing what is called
“chemical pulp.” After cooking, the pulp
undergoes its first wash in the digester
and results in a concentrated mixture
of fibres suspended in water. It is then
discharged into a discharge tank where
it is stored for transfer to the next stage
in the process.
It is interesting to note that most of the
heat and electricity needed to run the
pulping mill can be produced by burning
the fairly inflammable lignin removed
during pulping. And since lignin can be
chemically dissolved and washed out
of the pulp, the resulting pulp produces
brilliantly white paper that does not
discolour when exposed to air and light.
Pulp Purification
The objective here is to separate the pulp
fibres from the lignin dissolved during
cooking so that it may be washed out
from the cellulose fibres. In alkaline
washing, pulp is washed in a countercurrent flow washer and passes through
a series of filters. The pulp enters the first
filter and progresses toward the final
filter, while the alkaline washing water
enters the final filter and progresses
toward the first. The wash water thus
carries more and more of the dissolved
lignin and chemicals used in cooking,
thereby getting concentrated in to what
is called “brown stock wash.” This is
drained out. In the process, the fibres are
cleaned to a high degree. Next the pulp
is pumped to oxygen reactors where it
is maintained at controlled temperature
and pressure, receiving quantities of
oxygen and sodium hydroxide sufficient
to dissolve the remaining lignin within
the fibres. The pulp then goes through
a further purification process, where
small clumps of undercooked fibres
are removed, leaving the pulp free of
impurities.
Where a pulp mill uses non-wood
material like say bagasse, that too goes
through a similar process for producing
purified pulp, but in a continuous
chemical digester. However, this raw
material produces effluents like the
bagasse wash water obtained after
the first washing of bagasse and from
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subsequent pulping processes. This
wash water goes through an elaborate
treatment process and the resulting
recycled water is used variously for
agriculture, as process water in the
pulp mill, as feed water for boilers etc.
Another by-product from bagasse is the
pith separated from the fibres, which
again is used as fuel to fire boilers.
Bleaching
Though pulp is naturally white, the
separated lignin and the oxidized
organic matter in the wood change its
colour to light brown. Since paper needs
to be brilliantly white, this colouration
needs to be removed. To do this, the
pulp is bleached using oxidizing agents
in reactors with controlled temperature
and pH. This process is carried out
generally in three stages and at the
end of each stage the pulp is washed
in rotational filters in order to remove
coloured oxidized compounds. Since
the oxidizing process requires oxygen
gas, most mills have their own captive
oxygen generation plants, where oxygen
is extracted from air. The bleached
pulp, nearly white in colour, is stored
in storage towers before being sent for
the final stage in the process, which is
producing the paper.
Forming the Paper
In this stage of the process, the pulp
mixture is diluted with copious amounts
of water. This liquid pulp is then pumped
to the head box of what is called the
Fourdrinier Paper Machine. Pulps
from various sources like hardwood,
softwood, or chemical non-wood pulp
etc are mixed together in required
proportions depending on the quality
and characteristics required in the final
paper. Chemical additives like starch,
dyes, and talcum and other ingredients
like optical brightening agent, retention
drainage agent etc are added too to
impart various physical and chemical
properties to the finished paper. From
here, it is pumped to the paper forming
section which essentially consists of a
flow spreader that ejects a controlled
volume of the pulp through a wide and
narrow ‘lip’ to evenly spread the liquid
pulp on the fast moving Fourdrinier
table – an endless conveyor belt made of
wire mesh or a porous nylon sheet that
supports the pulp solids and allows the
water to drain through. This creates a
seamless length of fibrous web resting
on the porous mesh of the fast moving
conveyor belt. In the next press section,
the moving web of pulp is pressed under
steel rollers to squeeze out more of the
water. At this stage, the web sheet is
transferred to another conveyor belt
made of an absorbent felt material to
soak in more of the water. Then follows
the dryer section, where steam heated
Though pulp is naturally white, the separated lignin and the oxidized organic
matter in the wood change its colour to light brown. Since paper needs to be
brilliantly white, this colouration needs to be removed
Blow tank
Debarker
Chipper
Washer
Digester
Sawmill
The paper making process
Head box
Calendar stack After dryers
Size press Pre-dryers Press section
Web
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Foundrinier wire
Additive tank
Screen
Bleaching tower
Paper Properties and Parameters
Grammage: Weight per unit area expressed in g/m2.
Moisture Content: The absolute moisture content, expressed as a percentage of the weight of paper.
Thickness: The perpendicular distance between the two surface of the paper, expressed in mm or microns,
measured with a micrometer.
Water absorption: The surface water absorption is measured for 60 seconds, and expressed in g/m2.
Bursting strength: This is the maximum hydrostatic pressure required to rupture the sample.
Bending resistance/ Stiffness: It is a measure of the resistance offered to a bending force by a rectangular
sample, expressed in mN (milli Newtons).
Elongation: A measure of the maximum tensile strain the paper can withstand before rupture. It is measured as
the percentage increase in the length of the sample to the original length.
Compressibility: It is the reduction in thickness under compressive forces or pressure. It influences the tendency
of paper to change its surface contour under writing or printing pressure. It also governs the printing impression
formed on the paper.
Hardness: The degree to which paper will resist indentation by some other material such as a stylus, pen or
printing plate.
Resiliency: A measure of the ability of paper to recover its original thickness and surface contour once the
compressive load of printing nips or pen is removed.
Tearing resistance: A measure of the ability of the paper to withstand any tearing force that it is subjected to. It
is expressed in mN (milli Newtons).
Tensile strength: The tensile force required to produce a rupture in a strip of paper sample, expressed in kN/m.
Brightness: It is the percentage of blue light reflected off a sample measured at an effective wavelength of 457
nm.
Colour: A measure of the perception of colour of the paper. It is a measure of luminance and varies from 100 for
perfect white to 0 for perfect black.
Gloss: A measure of the specular reflection of light, which is reflected at an equal and opposite angle.
Opacity: The property of a substrate to resist passage of light. It is measured as the percentage of light absorbed
by a sheet of paper.
Print quality: A measure of the degree to which the appearance and other properties of a print approach a
desired result. It depends on various parameters of paper surface like roughness, gloss, ink absorption, brightness
and whiteness.
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55
Deinking Used Newsprint
Since newsprint paper contains the same fibres as the
original wood, these fibres can be re-used to make new
paper. However, the paper has to be deinked first before
using it to produce pulp. This operation typically starts with
loading the recycled paper into a large vessel filled with
water, then chopping and agitating it to separate the fibres
and then washing out the inks and other contaminants. The
combined action of water and mechanical action breaks
down the hydrogen bonds in the paper and the fibres are
separated. This paper slurry then goes through several
other mechanical and chemical treatments to recover as
much fibre as possible while continuing to remove ink,
colours, and other surface coatings. The extra mechanical and chemical stress damages and shortens the fibres,
limiting the number of times that paper can be recycled
to three to six times. Because recycled paper is a mix of
low and high-lignin papers containing inks, dyes, and other
contaminants, it commonly requires more bleaching. As a
result, fully recycled paper often has an off-white colour.
Centrifugal or reciprocating compressors of capacity sometimes in excess of
4,500 m3/hour are used in papermaking
rotating drums progressively dry the
pulp sheet as it passes over them, still
supported by the felt conveyor belt.
This section may also contain electric
heaters or convection-heating hoods. The
original web of pulp is now taking shape
as paper and the rapidly forming paper
sheet is now passed through sizing
presses – rotating rollers that compress
the paper to the required thickness. It
then passes through a series of calenders
– smooth steel rollers between which
the paper passes to gain a smooth and
glossy finish. Finally, the endless paper
sheet passes on to winders and reelers
that wind the paper onto core tubes. At
predetermined lengths, an automatic
slitting device snips off the paper and
winds the incoming sheet onto the
next core tube. The finished paper rolls
are massive, each weighing a few tons,
that are further sliced into smaller rolls.
These rolls may be shipped as they are
or shifted to a paper conversion section
where the continuous sheet is cut into
smaller sizes like A4, A5 etc meant for
writing and printing and packed in
cartons. Samples are taken from each
roll for testing of various properties and
parameters.
various areas in a pulp and papermaking
mill. Compressed air, nevertheless, is a
vital element at various stages of the
overall process of papermaking. It is used
in two distinct areas: as mill air used in
actual processes and, to power pneumatic
equipments and instruments. In the
first area, compressed air is distributed
to numerous sections of the plant like
the pulp mill, soda recovery plant,
energy generation, water treatment
plant, effluent treatment plant and
R&D laboratories. In the second usage,
compressed air is passed through a
drier and used for actuating a slew of
pneumatic instruments and equipments
such as control valves, dampers, testing
equipments, cutters and folders in the
paper conversion section etc. Generally,
either centrifugal or reciprocating
compressors of capacity sometimes in
excess of 4,500 m3/hour are used. In
fact, there is yet another section where
compressed air is indispensable: in the
automotive service section geared to
maintain huge earthmovers, trucks,
and loaders employed to handle logs,
mountains of wood chips or bagasse
piles in the raw material yard of a
modern pulp and paper mill.
Coming to a specific aspect of
manufacturing, the level of description
above has not been so exhaustive as to
bring in details of compressed air used in
Digressing once again, with abundant
vegetation and a vast plantation
network, added to the highflying IT
industry and a rich literary and printing
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heritage, India indeed has a vibrant
network of pulp and paper making
industries, ranking 15th among the paper
producing countries in the world. From
small pulp mills producing a few tons
per day (TPD) to integrated pulp and
paper plants with a capacity of over 1000
TPD, India straddles the whole gamut
in this unique industry. Tamil Nadu
Newsprint and Papers Limited (TNPL) is
a typical integrated plant. Established
by the Tamil Nadu Government in 1979
to manufacture newsprint and printing
& writing paper, this plant uses bagasse
as the primary raw material. The mill
is located at Kagithapuram in Karur
District in a sprawling campus of 830
acres. TNPL commenced operations in
1984 producing 90,000 metres of paper
per annum. By 1995 that capacity had
grown to 180000 metres. Today TNPL
has the capacity to produce a sizeable
4,00,000 tonnes per annum.
Elgi, a name synonymous with air
compressors for over fifty years, has
been catering to the needs of the pulp
and paper industry. Elgi’s centrifugal
compressors in the range of 2500-6000
cfm with an operating pressure of up
to 7 bar, oil-free screw compressors
between 700-1200 cfm also up to 7 bar
and lubricated screw compressors from
300-2000 cfm are the most commonly
used in this industry.
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THE ELGI MAGAZINE
57
Nuclear
Energy
Demystified
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THE ELGI MAGAZINE
BUSINESS SPOTLIGHT
The relatively tiny neutron split the nucleus of the
massive uranium atoms into two roughly equal pieces,
resulting in a complete rupture of the nucleus and
release of vast amounts of energy
The sweltering heat of summer under a
blazing sun might leave you exhausted,
but ever wondered what life on the
planet would be like without that
searing sun? It wouldn’t have existed!
That’s right, without the phenomenal
energy from that supportive star life
would not be possible on earth. That
apart, the sun also sets the rhythm
of our seasons and our climate. What
gives the sun such limitless energy?
Nuclear fusion is the answer. Like all
stars, the sun too is mostly made up of
vast amounts of hydrogen and helium
gases, and the atoms of these gases are
always in a state of flux colliding with
each other with tremendous force.
Nuclear fusion is the process by which
nuclei of rapidly colliding atoms fuse
together at very high temperatures at
the core of the sun, gaining extra protons
and neutrons (sub-atomic particles
contained in the nuclei of all atoms) in
the process to form heavier nuclei. While
the colliding atoms gain some mass thus
increasing their atomic weight, some
mass scattered during collisions gets
converted to energy. Hence, this process
releases vast amounts of energy. And
this ‘atomic’ or ‘nuclear’ energy is the
secret behind the sun’s phenomenal
power. What if we could replicate that
process on earth to meet our own energy
demands? We are already doing some
such work in our nuclear power plants.
We do not however replicate nuclear
fusion like on the sun; rather, the process
used is nuclear fission. What’s the
difference? A nuclear reactor in a power
plant produces and controls the release
of energy from splitting the atoms of
certain elements, rather than fusing
their atoms together. Nuclear power
generation utilizes sustained nuclear
fission to generate heat and electricity.
Although research on fusion power (like
on the sun) has been going on since the
1950s, these reactions have proved to be
technically quite difficult and have yet to
be created on a scale that could be used
to produce commercial electrical energy.
But nuclear fission lends itself quite well
to power generation.
The evolution of nuclear studies began
in the late 18th century when Uranium
was observed for the first time and
named after the planet Uranus, by noted
German scientist Martin Klaproth in
1789. However, the pursuit of nuclear
energy only began after the discovery in
early 20th century that some elements
like radium are radioactive, that is, they
released immense amounts of energy
when their nucleus spontaneously
disintegrated – following an impact with
a sub-atomic particle. However, early
attempts to harness such energy were
impractical. This situation changed a
few decades later when nuclear fission
was discovered in the 1930s. It began in
1932 when James Chadwick discovered
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59
the neutron, so named because it was
electrically neutral or carried no electric
charge. This made it an ideal candidate
with which to impact and split a nucleus.
Experiments with bombardment of
materials with neutrons led to the
creation of radium-like elements
that were cheaper to produce when
compared to naturally occurring radium
that was hitherto very expensive to
isolate. Further work by Enrico Fermi
in mid 1930s, who experimented with
bombarding uranium with neutrons,
led to increasing the effectiveness of
induced radioactivity, that is, release of
energy.
But in 1938, German chemists and
Austrian
physicists
conducted
experiments with the products of
neutron-bombarded
uranium,
and
determined that the relatively tiny
neutron split the nucleus of the massive
uranium atoms into two roughly equal
pieces, resulting in a complete rupture of
the nucleus and release of vast amounts
of energy. The scientists recognized that
if fission reactions released additional
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image: nrc.gov
Electricity was generated for the first time by a nuclear reactor on December 20,
1951, at the EBR-I experimental station in Idaho, US, which initially produced about
100 kW
neutrons, those
neutrons
would
continue the bombardment and a selfsustaining nuclear chain reaction could
result, releasing enormous amounts of
energy. The process was duly named
nuclear fission. In the late 1930s, the
world was on the cusp of World War
II and the situation was ripe for the
new discovery. Scientists in the US, the
UK, France, Germany, and the Soviet
Union approached their governments
for support to advance nuclear fission
research.
In the US, this led to the creation of
the first man-made reactor, known
as Chicago Pile-1, which went critical
(commissioned) on December 2, 1942.
This soon became part of the Manhattan
Project, under which large reactors were
built to breed plutonium for use in the
first nuclear weapons. This became a
major impetus to the concept of the
atomic bomb. It was established that an
amount of about 5 kg of pure uranium (U235) could make a very powerful atomic
bomb equivalent to several thousand
tons of dynamite. British and American
scientists collaborated on developing
an atomic bomb and on the insistence
of Prime Minister Winston Churchill,
US President Roosevelt accelerated the
program for development of the bomb.
The first nuclear weapon was tested in
the US state of New Mexico on 16th July
1945. As the war escalated to a decisive
moment, US fighter planes dropped the
newly invented atomic bombs on the
twin Japanese cities of Hiroshima and
Nagasaki on 6th and 9th of August 1945
– and the world witnessed the horrifying
effects of atomic bombs! That moment
also marked the end of World War II.
After the war, the focus shifted to using
atomic energy for good, mainly for
power generation. Following research
by both the US and the erstwhile USSR
in the 1940s, electricity was generated
for the first time by a nuclear reactor
Fuel Assembly
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61
made of zirconium alloy, the zirconium
being hard, corrosion-resistant and
permeable to neutrons. Numerous
rods form an open lattice of the fuel
assembly, which can be lifted into and
out of the reactor core. These assemblies
are commonly between 3.5 and 4 metres
long. During the process of fission, most
of the neutrons are released promptly,
but some are delayed. This is crucial
in enabling a chain reaction to take
place that can then be controlled and
maintained at a safe, precisely critical
level. The chain reaction becomes selfsustaining because when a uranium
atom splits (or fissions) in the reactor’s
core, the neutrons released cause
other uranium atoms to also undergo
fission. Controlling the chain reaction is
achieved by the use of a moderator. This
is a material in the core of the reactor,
which slows down the neutrons released
from fission so that they can continue
to cause more fission. Though earlier
reactors used graphite, present day
The chain reaction becomes self-sustaining when the neutrons released cause other
uranium atoms to also undergo fission. Controlling the chain reaction is achieved
by the use of a moderator
Going critical
In a new reactor with new fuel, a neutron source
is needed to initiate fission. Usually this is a
neutron emitter like beryllium mixed with polonium
or radium. Alpha particles from the decay of
the emitter cause a release of neutrons from
the beryllium as it turns to carbon-12. However,
restarting a reactor containing some used fuel may
not require this, as there may be enough neutrons
to achieve criticality when its control rods are
withdrawn.
on December 20, 1951, at the EBR-I
experimental station in Idaho, US,
which initially produced about 100 kW.
Installed nuclear capacity rose quickly,
rising from less than 1 Giga Watt (GW)
in 1960 to 100 GW in the late 1970s, and
300 GW in the late 1980s. Since the late
1980s, worldwide capacity has risen
much more slowly, reaching 366 GW in
2005. As of March 1, 2011, there were 443
operating nuclear power reactors spread
across the globe in 47 different countries.
So what exactly goes on inside a nuclear
power plant? To put it very simply, the
energy released from continuous fission
of the atoms of the fuel (radioactive
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elements like Uranium or Plutonium) in a
nuclear reactor is harnessed as heat and
is used to produce steam. The steam is
used to drive turbines that power electric
generators that produce electricity (same
as in any thermal power plant burning
fossil fuels like coal or gas).
The fuel most commonly used in a
nuclear reactor is pellets of Uranium
Oxide (actually ceramic Uranium
Oxide with a melting point of 2800°C)
that are arranged in tubes to form
fuel rods. The rods are then sealed and
assembled in clusters and arranged
to form fuel assemblies in the reactor
core. Typically, the long tubes are
nuclear reactors employ what is called
heavy water. The two hydrogen atoms
in a molecule of normal water H2O are
replaced with two atoms of its isotope
deuterium to make it D2O. That makes
it about 11% denser than normal water,
slightly more alkaline and with a slightly
higher boiling point and a slightly
lower freezing point, but otherwise,
is physically and chemically similar.
Incidentally, India is the world’s largest
producer of heavy water. This water with
a different molecular structure absorbs
far less neutrons than normal water
and therefore makes an ideal neutron
moderator to slow down the neutrons.
To further control the rate of reaction,
BUSINESS SPOTLIGHT
Daiichi nuclear facility in Japan recently
when the powerful earthquake and
the ensuing tsunami resulted in water
draining out from the reactor core,
making it impossible to control core
temperatures, which ultimately resulted
in overheating and a partial nuclear
meltdown.) In the process, the water is
heated to a very high temperature way
beyond its normal boiling point, but
does not flash into steam because of the
very high pressure within the system.
At atmospheric pressure, water boils at
1000C, but under high pressure, water
can remain in liquid form even when
its temperature is raised way beyond its
normal boiling point. Within a nuclear
reactor, the circulating water can heat
up to nearly three times its normal
boiling point. Since this water is in direct
contact with the reactor core, it would be
radioactive and so a completely isolated
secondary coolant circuit is employed
where the steam is generated. The
extremely hot heavy water circulating in
the primary circuit through the tubes of
the reactor core acts as a heat source for
a boiler, or steam generator, which boils
water circulating through a secondary
circuit and raises steam for the turbine.
The structure housing the steam turbine
too is usually separated from the main
The damaged chernobyl reactor plant
or to halt it when required, control
rods made of other neutron-absorbing
materials such as cadmium, hafnium
or boron, are either inserted deeper
into the core or withdrawn from it to
maintain the required rate of reaction.
Complete insertion and addition of other
neutron absorbers would mean not only
limiting the multiplication of neutrons
but also almost total absorption of the
released neutrons that would then result
in stoppage of the nuclear reaction itself
enabling a shutdown.
How is the heat produced in the reactor
harnessed? The reactor core is contained
within a structure designed to protect
it from outside intrusion and to protect
those outside from the effects of
radiation should there be a malfunction
inside. It is typically a concrete and steel
structure nearly a metre thick. Within the
containing structure, a pressure vessel,
usually a robustly built steel vessel,
houses the reactor core, through which
the moderator/coolant is conveyed. A
liquid, and sometimes gas, is circulated
through the core so as to transfer the
heat generated from the fission of the
fuel. The circulating water functions both
as a moderator and as a coolant for the
radioactive material, preventing it from
overheating and a potential melt down
(this is what happened in the Fukushima-
reactor building and is hermetically
isolated from the nuclear system. The
steam turbine essentially converts the
heat contained in steam into mechanical
or kinetic energy when the jet of highpressure, super-heated steam hits the
blades of the turbine and rotates the
turbine. The generator coupled to the
turbine, converts the rotary motive drive
from the turbine into electrical energy.
How safe are nuclear power plants? On
one hand, nuclear power offers a ‘clean
energy’ that is a viable alternative to
dependence on fossil fuel. On the other,
it conjures up images of disaster: The
quake-ruptured Japanese power plants
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63
Nuclear
Wastes
Unlike thermal power plants that burn coal or gas, nuclear power plants do not emit carbon dioxide in to the
atmosphere, and therefore hardly has any environmental impact on a daily basis.
However, spent fuel forms the main waste produced by fission of uranium in a nuclear reactor and that is a
radioactive material. Nevertheless, such nuclear wastes are modest in quantity. Handling and storing them
safely simply means that they need to be shielded from human exposure, and cooled. Water, concrete, steel or
other dense materials are used for shielding, while cooling is by air or water. When spent fuel is removed from
a reactor, it is done under water and the used fuel is transferred to a large storage pool where it may remain
for several years to allow most of the radioactivity to decay. Then either it can be reprocessed to recover the
reusable portion, or it may be disposed of as waste. In reprocessing, the used fuel is dissolved and the uranium
and plutonium in the used fuel are separated from the waste. Plutonium can then be combined with uranium to
make Mixed Oxide Fuel (MOX), which can be used in many modern reactors. And reprocessed uranium can be used
as new uranium oxide fuel.
Nuclear power plants generate other radioactive wastes too but these are more easily handled and disposed of.
One characteristic of all radioactive wastes is that their radioactivity progressively decays and diminishes. For
instance, after 40 years, spent fuel removed from a reactor has only one thousandth of its initial radioactivity,
making it quite easy to handle and dispose of. They are finally put into specially engineered underground
repositories.
Safe operation of a nuclear power plant demands a high degree of automation so that
human intervention is kept to a minimum, not only to eliminate human error but also
to ensure safety of the personnel
and the earlier Chernobyl meltdown. The
nuclear power plant thus stands today
on the border between our hopes of a
viable, comparatively cheaper energy
to spur our future growth and our deep
fears of potential nuclear disasters.
Those fears have been allayed to a
great extent though by the increasingly
stringent safety measures built into the
technology of present day nuclear power
plants, astutely designed to protect public
health and safety. Indeed, a significant
proportion of the cost of a typical reactor
is due to safety systems and structures
(nuclear power reactors are expensive
to build but relatively cheap to operate.)
These are defined and codified by
nuclear safety regulations and monitored
by Nuclear Regulatory Commissions.
Today, active research is under way on
number of new designs intended for
nuclear power generation in the future.
Many of these new designs specifically
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attempt to make fission reactors cleaner
and safer.
Safe operation of a nuclear power plant
demands a high degree of automation
so that human intervention is kept
to a minimum, not only to eliminate
human error but also to ensure safety
of the personnel. Understandably, most
operations are automated. The multitude
of valves regulating the flow of various
mediums through miles of pipelines is
pneumatically operated. There’s a high
degree of pneumatic operation in the
reactor room too. Compressed air is again
used to start up standby generators that
every nuclear power plant carries in order
to supply standby power so that essential
operations are kept going in case of an
emergency shut down. It is also used
in masks and body hugging suits that
technicians wear for safety and breathing
while working in hazardous zones
within the reactor room. Compressed air
stream through full-body armour suits
and the mask creating a barrier between
possibly radiation-contaminated air and
the human body.
Various types of air compressors
manufactured by Elgi cater to these
diverse needs in different nuclear
power plants across India. For instance,
India’s largest nuclear power plant, the
Tarapur atomic power station, located
on the west coast 130 km north-west of
Mumbai has number of reciprocating
and screw air compressors from Elgi
working in different areas of its plant.
High-pressure Elgi Sauer compressors,
with working pressures between 25450 bar are examples. Some of these are
used as gas booster compressors to
compress nitrogen, helium, and argon up
to 350 bars.
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65
5D
magic
I felt the coolness as the morning breeze
caressed my cheeks. The city skyline
stood silhouetted against the bright
blue sky even as the metropolis was
waking up to its daytime tempo. Early
office goers whizzed past in gleaming
cars while red-hued buses moved at a
more sedate pace on meandering roads
already buzzing with the day’s activity.
The city was catching up swiftly with its
daily rhythm of life.
So the loud rumbling that seemed to
come right out of the bowels of the earth
jolted the citizenry – snatching them
rudely out of the predictable dullness of
daily routine. I felt the tremor go right
through me. What was a soft breeze
few minutes ago roared into a gale. A
blast of wind hit my face followed by
another jarring tremor. The rumbling
grew louder, and skyscrapers picked up
the vibrations from the earth. Cracks
and fissures appeared on walls and
facades, and ran across buildings much
like streaks of lightning ripping across
the sky. Streets began to heave and tall
buildings tottered on their base. I was
pulled toward one side, then the other,
see-sawing and pitching back and forth
like a rag doll in Godzilla’s hands. Rubble
careened towards me…I could feel it
against my legs. Toppled cars and buses
came crashing, heading my way and
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I steeled myself for head on collisions.
But at the very last moment I escaped
the impact. A blinding light is all I had to
endure. The same with massive chunks
of concrete and glass hurling towards
me – no impact, but only a blinding flash
of light. Water, possibly from a ruptured
tank on some building, came cascading
down…but I got only a shower that
hardly drenched my clothes.
No, I’m not in deep slumber. And I’m
neither dreaming nor hallucinating.
Stumped?
I’m actually sitting inside a darkened
theatre, watching a movie…a 5D movie.
But it’s all not merely virtual reality. The
3D goggles I’m wearing creates a very
truthful illusion of three dimensions,
so everything on the screen looks real,
rather than merely moving pictures.
The shower is real water spraying on
me; the tremor is real too felt through
the cushioned chair I am sitting on, the
sounds are overwhelmingly realistic,
booming through multiple, high-volume
speakers. Debris hitting my legs is plastic
tube-ends under the seats that lash out
when compressed air streams through
them. The blinding light comes from
strategically placed strobe lights.
So what exactly is a 5D movie? It’s a
3D movie with added physical effects
designed to bring the viewer closer
to reality. For both practical and
technological reasons only animated
movies are adapted for 5D viewing right
now – and the duration is generally from
5 to 15 minutes, or may be slightly longer.
It might have already occurred to you that
the success of 5D lies in how closely the
scenes on the screen are synchronized
with the physical effects created inside
the theatre. The closer they match, the
more authentic the impact. Earthquake
tremors have to be well co-ordinated with
appropriate vibrations and jolts from the
viewer’s chair; the chairs also have to
mimic realistically the movements of a
roller-coaster ride shown on the screen,
or the careening motions of a speeding
car. To match the on-screen visuals of
being hurled towards the sky, the chairs
tilt back and swiftly move upward as
you are buffeted with wind rushing at
you from the wall-mounted blowers,
and to simulate a free fall seen on the
screen, the chairs tilt forward and slide
downward. Water sprays emitted from
overhead nozzles mimic rain; nozzles
discretely attached to seat backs buffet
you with puffs of air to simulate wind
from behind; bubble machines spewing
soap bubbles and swaying chairs
replicate underwater scenes; scattered
foam emitting from ‘snow machines’
mimic falling snow, even atomisers
BUSINESS SPOTLIGHT
located on walls eject timely perfume
sprays to enhance the effects of a garden
resplendent in fragrant blooms; and
well-timed blasts from wall-mounted air
blowers that respond swiftly to electrical
signals simulate the effects of being
caught in a gale.
If the effects sound fascinating, the
technology behind them is no less
interesting. It involves both creativity
and engineering. Deciding on the kinds
of effects to realistically mimic the scenes
on the screen is the creative part, while
capturing those constantly changing
scenes and creating the corresponding
signals needed for actuating the various
equipments is where engineering
comes in. Understandably, all this is
done through computer programming.
“Our programmers sometimes view
a five minute clip for up to fifty times
to capture every individual scene,”
says Ankur Maheshwari of Modern 5D
located in Gwalior, MP, manufactures
of 5D equipments. “We strive to capture
scenes that last barely 50 milliseconds
on the screen,” says Ankur, “and generate
the necessary signal to create that effect
for the audience.”
A line of up to four specially made chairs
are bolted to a steel base that also houses
solenoid valves and proportional control
valves to actuate pneumatic cylinders
under the chairs. These chair clusters are
laid out on tiered steps inside the theatre.
Compressed air is also supplied to the
seat back nozzles. Water lines coming
from a pressure vessel are similarly
connected to spray heads mounted on
the roof as well as lines running along
the front of the seats with individual
nozzles for each chair. Small pneumatic
cylinders embedded in the seat back
poke the viewer’s back. Booming
surround sound from speakers, strobe
lighting, bubble machine and snow
machine complete the picture. Horror
movies, adventure and disaster, wildlife
and the like that have ample scope for
creating viewer impact are the common
themes of these short movies. Whereas
3D is entirely visual, merely enhancing
the illusion of depth perception, 4D
has moving chairs, while 5D has effects
that impact your skin and perfumes
for the olfactory sense. 5D theatres are
increasingly becoming popular in India
and are now found in malls, shopping
districts, fairs and such other places.
Theatre sizes vary from 10-seaters
to 32. The air compressor is installed
in a room behind the small theatre.
Compressor capacity varies from 10
Whereas 3D is entirely
visual, merely enhancing
the illusion of depth
perception, 4D has
moving chairs, while 5D
has effects that impact
your skin and perfumes
for the olfactory sense
HP for a 10 seater to 20 HP or more for
higher seat capacities. Reciprocating air
compressors with pre-filter and drier,
and a refrigerated moisture remover are
generally used. Only distilled water is
used in water sprays to ensure hygiene.
Elgi compressors are used by many 5D
equipment manufactures in India, like
the Modern 5D of Gwalior. Though the
working environment is not harsh for
the air compressor, low noise is a prime
concern in this application. So package
compressors with low noise levels are
preferred.
n
3D Movies
Actually, 3-D films are nearly a century old – since June 10, 1915 to be
precise, when Edwin S. Porter and William E. Waddell presented test
clips to an audience at the Astor Theater in New York. Nevertheless, it
had been largely relegated to a niche in the motion picture industry,
mainly due to the costly hardware and processes required to produce
and display a 3D film. Lack of a standardized format for the films also
proved a deterrent to its progress. That said, 3D films were prominently
featured in the 1950s in American cinema. But though it had been on
the wane since then, there was a worldwide resurgence in the 1980s and
‘90s driven by IMAX high-end theaters and Disney themed-venues. The
last decade saw 3D films becoming more and more successful, and the
unprecedented success of 3D movie Avatar in 2010 perhaps foretells
another revival.
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67
The Alluring World of
Aluminum
There was a time in history when
aluminum was considered such a
valuable commodity that the royalty
preferred impressing their guests with
plates and cutlery made from aluminium
rather than gold and silver. That indeed
underlines the arduous task and the
high cost of extracting aluminum from
its natural compounds that the pioneers
faced. For instance, in 1854 Frenchman
Henri Sainte-Claire Deville created the
first commercial process for producing
aluminum which, at that time, was more
valuable than gold. Nevertheless, though
aluminium as a metal is only 160 years
old, aluminium-bearing compounds
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have been used by man from the earliest
times. Around 5000 B.C., Persian potters
made their strongest vessels from clay
rich in hydrated silicates of aluminium.
Aluminum salts have been used by
ancient Middle Eastern civilizations for
the preparation of fabric dyes, cosmetics,
and medicines. Indeed, they are used
even today in indigestion tablets and
toothpaste! However, it is only 100
years – since early nineteenth century
– that a viable production process
was established for manufacturing
aluminium.
Despite
that,
today,
aluminium has become indispensible to
our daily lives – from cola cans to bicycles,
BUSINESS SPOTLIGHT
wrapping foil to windows, and pots and
pans to aircraft. Interestingly, the role of
this light, durable and flexible metal in
air and space travel was foreseen more
than 100 years ago. In 1865, when Jules
Verne wrote From the Earth to the Moon
about the fictitious first attempt to send
man to the moon, the metal he chose to
build his spacecraft was aluminium. And
fifteen years later J.W. Richards wrote, “It
has been well said that if the problem
of aerial flight is ever to be solved,
aluminium will be the chief agent in its
solution.”
There are other interesting facts
too about aluminium: it is the most
abundant metal on the earth’s crust,
nearly 8%, and the third most abundant
element in nature. But aluminium never
occurs naturally in its pure metallic form.
The chief source of aluminium is bauxite
ore – discovered in 1821 by P. Bertheir,
who discovered a hard, reddish, claylike material containing 52% aluminium
oxide near the village of Les Baux in
southern France. He called it bauxite,
after the village. However, the existence
of aluminium was established by English
chemist Sir Humphry Davy one year
earlier, in 1808. Aluminium is also found
in a number of minerals, including some
precious stones like rubies, sapphire
and garnet, but it can be economically
extracted only from bauxite. How did the
metal get its name? The word aluminium
is derived from the Latin word for alum,
alumen. Actually, much earlier, in 1761
itself, L. B. G. de Moreveau had proposed
the name alumina for the base in alum
and in 1787 it was successfully shown
that the base was the oxide of a yet to be
discovered metal.
How is aluminium oxide reduced to its
pure metal form? Initially, aluminium
was produced by reduction with alkali
metals. In 1825 Danish physicist H.C.
Oersted produced the first pellet of
aluminium using this process, though it
C. M. Hall and Paul Héroult
In 1865, when Jules Verne wrote From the Earth to the
Moon about the fictitious first attempt to send man to
the moon, the metal he chose to build his spacecraft
was aluminium
was very expensive and faced number
of technological challenges that made it
economically unviable. However despite
these limitations, scientists continued
to experiment with the process. The
exorbitant cost of producing aluminium
was further underlined when, in 1855,
Frenchman Henri Saint-Clair Deville
displayed a solid bar of aluminium
at a Paris exhibition. Predictably, the
production cost of the metal was
higher than that of gold or silver. But in
1886, working in a woodshed in Ohio,
Charles Martin Hall made a discovery
at the same time that metallurgist Paul
Lois Toussaint Héroult made the same
discovery in a makeshift laboratory
in Gentilly. Both men dissolved
aluminium oxide in molten cryolite
and then extracted the aluminium by
electrolysis. This cost-effective method
invented simultaneously by C. M. Hall
and Paul Héroult, came to be called
the Hall-Héroult electrolytic method,
which was economically quite viable.
However, the raw material alumina had
to be purified first, in order to be used
in the Hall-Héroult process. In 1888,
Carl Josef Bayer, an Austrian, and son
of the founder of the Bayer chemical
company, invented an improved process
for making aluminium oxide or alumina
from bauxite. This method came to be
called the Bayer process. Within the
next two years, the first aluminium
companies were founded in France, then
USA and Switzerland. By 1890 the cost
of aluminium had tumbled nearly 80
percent.
Mining the Ore
But the story of aluminium production
really begins with the bauxite ore, which
is a naturally occurring non-renewable
resource found mostly in tropical and
subtropical regions, in coastal areas or
even in rain forests. Three countries
account for 60% of world’s bauxite
output namely, Australia, Guinea and
Jamaica, out of an estimated world total
production of well over a million tonnes.
The West African country of Guinea is
the world’s leading producer of bauxite,
with an estimated deposit of around 10
billion tons. That’s nearly 50% of the total
world reserves.
Bauxite is a mixture of aluminium
oxides and hydroxides formed from
intense chemical weathering of soil in
tropical environments over millions of
years. Such weathered soil transforms
THE ELGI MAGAZINE
69
into rocks called laterites. When lateritic
rocks undergo further weathering –
leached over eons by rain, groundwater,
or salt spray in coastal areas – the
minerals contained in them decompose.
This removes much of its silica content
and turns the deposits into concentrated
aluminium oxides and hydroxides.
However, bauxite contains only about
30 to 55% aluminium oxide, because this
heterogeneous ore also contains various
mixtures of silica, iron oxide, titania or
titanium dioxide, and other impurities
in minor quantities. Bauxite is mined
through various means but the most
common is what is called as surface
mining, which is considered the most
practical and economical method. Eighty
percent of bauxite mining in the world
is through surface mining with the rest
from underground excavations. In the
case of surface mines, the ore is exposed
on the surface as either outcrops or lies
beneath a thin layer of sedimentary
cover. Geologists locate ore deposits
through a process known as prospecting,
involving
drilling
bauxite-bearing
regions to source core samples. Analysis
of core samples then help in determining
both the quantity and quality of the
bauxite reserves. Interestingly, bauxite
has other commercial applications
too: in abrasives, cement, chemical,
metallurgical, refractory etc.
Once the ore is discovered and viable
reserves are established, bauxite is
mined from open-pit mines, which
essentially mean quarrying the ore from
an open pit using explosives to blast
away surface layers of earth, then using
bulldozers and earthmovers to quarry
the ore. The ore is crushed, then washed
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India too is naturally endowed with large deposits
of bauxite. That makes India a leading aluminium
producer in the world. On a global scale, India ranks
as the fifth biggest alumina producer and the eighth
biggest producer of primary aluminium
to remove impurities then dried prior to
transport to the refinery in the form of
lumps, granules or powder. It takes about
2 kgs of bauxite to produce half a kilo of
aluminium metal. Alumina refineries
are generally set up close to the mines to
reduce transportation costs. Bauxite ore
is mined primarily in Australia, Africa,
South America and the Caribbean; but
India too is naturally endowed with large
deposits of bauxite. That makes India
a leading aluminium producer in the
world. On a global scale, India ranks as
the fifth biggest alumina producer and
the eighth biggest producer of primary
aluminium.
As mentioned, bauxite refining is
achieved primarily through the Bayer
Process, which involves the separation
of aluminium oxide or alumina from the
bauxite ore. Aluminium metal is then
extracted from alumina through the
process of smelting. The Hall-Héroult
The Bayer’s method of Alumina production
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71
Captive Power Generation
Aluminium production is very energy-intensive. The reduction of
aluminium from alumina by means of electrolysis requires substantial
amounts of power; making it necessary for most vertically integrated
companies to generate their own power. Accessibility and the price of
power provide further reason to aluminium industries to go in for captive
power. Regions or countries that have natural resources for cheap
generation of power therefore derive an advantage over industrially
developed countries that may have better technological advantages
for aluminium production. For example, regions with abundant reserves
of coal have a clear advantage; for coking coal is needed not just for
making carbon anodes for the electrolytic reduction of aluminium but is
also an ideal fuel for captive thermal power plants.
Reduction pots are arranged in rows called pot-lines consisting of 50 to 200 pots
that are connected in series to form an electric circuit. Each pot-line can produce
60,000-100,000 metric tons of aluminium per year
electrolysis process is now the globally
accepted standard for aluminium
smelting. First, a solution is prepared by
dissolving alumina in molten cryolite,
which is a chemical compound of
fluorinated aluminium. The cryolite
allows electrolysis to occur at a lower
temperature. This bath is held in a steel
or iron vat with graphite lining and
is called a reduction pot. The graphite
serves as the cathode. Carbon anodes are
then immersed in the electrolyte. These
consist of a set of pre-baked carbon rods,
or carbon blocks moulded around suitable
steel electrodes and baked in huge
furnaces. Reduction pots are arranged in
rows called pot-lines consisting of 50 to
200 pots that are connected in series to
form an electric circuit. Each pot-line can
produce 60,000-100,000 metric tons of
aluminium per year. A typical smelting
plant consists of two or three pot-lines.
A high intensity DC current of only 4 to 6
volts but 100,000 to 230,000 amperes is
passed through the solution. Aluminium
settles to the bottom of the pot as
molten metal. Thus, molten aluminium
metal is deposited at the bottom of
the cathode as a pad while carbon at
the anode is oxidized by the oxygen
to form carbon dioxide. The smelting
operation requires large amounts of
electrical energy – 15 kilowatt-hours for
every kilo of aluminium produced, the
cost of electricity representing nearly
20% to 40% of the cost of producing
aluminium. The pure molten aluminium
accumulating at the bottom of the pot
is periodically removed by siphoning
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Bus bar
Steel lining
Carbon anode
Cryolite
Molten Aluminium
Carbon cathode lining
The Hall and Heroult’s method of Aluminium Reduction
drugoi.livejournal.com
BUSINESS SPOTLIGHT
or by vacuum methods into crucibles.
The separated metal is then transferred
to casting facilities where they are remelted to produce ingots, wires or rods.
Subsequent refining techniques such as
fractional crystallization and Hoopes cell
operation enable obtaining high levels of
purity, as high as 99.99%.
There are number of industrial processes
that convert ingots into different
aluminium products – like casting,
rolling and extrusion.
Casting is the oldest and simplest means
of manufacturing shaped components.
Casting is carried out in what is called a
‘cast-house,’ where ingots are heated in
electric furnaces into a molten state then
pored into moulds in casting machines.
Under die-casting, molten aluminium
metal is poured into mould cavities
under high pressure. The cavities are
machined into required size and design
and actually form dies. This method is
ideally suited for producing number
of small to medium sized parts with a
fine surface quality and dimensional
consistency.
Rolled products like sheets, plates
and foils are manufactured using this
process, which employ series of heavyduty rollers that flatten suitably shaped
ingots into sheets. Sheet and foil are
used extensively by the packaging
industry for making beverage cans, foil
containers and foil wrapping. Apart from
packaging, foils find wide applications
in electrical equipment, insulation for
buildings, lithographic plate and foil for
heat exchangers.
As the term suggests, extrusion is the
process of forming a section by pushing
a hot cylindrical billet of aluminium
through a shaped die. The resulting
section can be either circular, forming
a rod, or of any desired shape that can
Recycling
Aluminium is easily recyclable. It can be recycled over and over again
without loss of properties, which is a major advantage of this versatile metal.
However, it’s not just an economic advantage but has far-reaching ecological
and social implications too. Little wonder, more than half of all the aluminium
currently produced in the European Union originates from recycled raw
materials – a trend that is on the increase. Predictably, this is not just an
economic necessity, but is driven by number of other considerations – like
domestic energy constraints, growing aluminium end-user demands and the
small number of bauxite mines in this part of the world. Europe perforce
has to maximize collection of recyclable aluminium parts and develop the
most resource-efficient scrap treatments and melting processes in order to
conserve not just natural resources but energy too. For example, re-melting
used aluminium saves up to 95% of the energy needed to produce the
primary metal.
Understandably, aluminium scrap
commands a high value, which is a
key incentive and major economic
impetus for recycling. Furthermore,
aluminium recycling helps in avoiding
corresponding emissions and
greenhouse gases. Today, growing
markets for aluminium are supplied by
both primary as well as recycled metal
sources, though the overall volume of
primary metal produced from bauxite
will continue to be substantially greater
than the volume of recycled metal
currently available. However, studies
have established that with support
from appropriate authorities, helpful
legislation, local communities and
society as a whole, the amount of
aluminium collected could be increased
further. For example, about 60% for
beverage cans currently produced
the world over come from recycled
aluminium; but with concerted effort, this can easily go up.
clockwise from left : the reduction pots, the carbon anode, the pots connected in series, the molten aluminium
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73
image: igor.ch
image: igor.ch
World production of aluminium has soared from less than 200 tonnes in 1885 to
nearly 25 million tonnes today
be cut into short lengths for use in
structures, vehicles or components.
Extruded aluminium is also used
extensively in the building industry
for window and door frames. Extruded
products constitute more than 50 % of
manufactured aluminium products.
World production of aluminium has
soared from less than 200 tonnes in 1885
to nearly 25 million tonnes today. And
the prophecies of Verne and Richards
have come true as well.
Compressed air plays a crucial role in the
entire process of producing aluminium:
in the mines to operate pneumatic
components of mining equipments;
in ore refineries to actuate pneumatic
equipments, digester etc; in the smelting
process to liquidise alumina in order to
make it flow easily into smelting pots
and in extracting the molten aluminium
from the pots, and finally in the casting
process to operate specialised pneumatic
equipments and actuators. Different
types of Elgi air-compressors have been
increasingly used in this industry from
small private smelters to government
owned integrated aluminium companies
and have been operating creditably
under demanding and very exacting
working conditions. National Aluminium
Company Ltd (NALCO), located in Angul,
Odisha for instance, uses Elgi’s highpressure ompressors in its smelter unit,
and to actuate pneumatic equipments in
other operational areas.
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Aluminium Cables
Wires and cables are some of the most widely used aluminium
products. Typically, these are made from aluminium wire stocks of
around 10 mm diameter obtained from aluminium smelting plants
like Nalco, Balco and Hindalco in India. These are then re-drawn
to the required smaller diameters ranging from 1.5 to 2.5 mm
by pulling the wire through a series of die-holes with reducing
diameters. Cold-drawn wires are then stranded or bunched on
what are called armouring machines. The bunched wires are
twisted in a process called laying, in order to impart mechanical
strength. Next is insulation where the bunched and twisted cable
is coated with PVC to provide insulation. High voltage cables
are strengthened further with an armour coat made of either
aluminium strips or wires wound around the PVC. Another outer
sheath of tough PVC follows. The cable is then subjected to a
series of tests to ascertain its mechanical, electrical and fire
resistant properties.
Compressed air is used at various stages in the manufacturing
of cables and wires. To stop the heavy fast rotating bunching
machines, pneumatically operated brake drums are employed.
After PVC sheathing, compressed air is used to blow away
cooling water from the hot PVC covering. Again, pneumatic
pulling machines are employed in order to pull heavy, armoured
cables from large spools and feed it into the next machine for
further operations. Elgi’s compressors are widely used by cable
manufacturers all over India. KEI, a leading cable manufacturer
located in Bhiwadi, Rajasthan uses number of these compressors.
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75
Bergie
Seltzer
compressed air in nature
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Ever heard a giant burp? A sea giant at that? Ask sailors
and submariners and they’ll tell you it’s not an ear-splitting
roar as might be expected, but a continuous crackling,
frying sound they’ve often heard close to the Polar Regions.
This sound is made by the large volume of air bubbles the
giant emits periodically. If that sounds mysterious, the
fizzing sound of the giant’s burp even has a strange name.
It’s called “Bergie Seltzer.” What giant are we talking of?
It’s actually a gargantuan chunk if Ice! A chunk of ice larger than
the size of a country! And it’s called an iceberg. That’s right, an
iceberg sighted in the southern Pacific in 1956, the largest recorded
so far, covered an area of about 31,000 square kilometres – larger
than BElgium, which measures only 30,519 square kilometres.
Bergie Seltzer is heard when compressed air trapped in the
iceberg pop. The bubbles are generated from air trapped and
preserved in snow layers for eons that later become glacial ice.
THE ELGI MAGAZINE
77
After hundreds of years, the layer of snow deepens and squeezes the snow below
it until it develops into a massive hulk of solid ice spread over an entire mountain
valley. In the process, along with snow, air trapped within its layers also gets
compressed
What are icebergs, and how are they
formed? Contrary to general belief, an
iceberg is made of fresh water and not
frozen seawater. It is estimated that
about one-tenth of the earth’s surface
is permanently covered with ice – most
of it in Antarctica in the south and
within the Arctic Circle in the north
– and most of this ice is in the form of
glaciers, which is compressed, packed ice
formed out of falling snow on the polar
mountains. After hundreds of years, the
layer of snow deepens and squeezes the
snow below it until it develops into a
massive hulk of solid ice spread over an
entire mountain valley. In the process,
along with snow, air trapped within its
layers also gets compressed. Ultimately,
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THE ELGI MAGAZINE
when the growing, spreading glacier
reaches the sea, it breaks off into pieces
or sometimes an entire ice shelf begins
to float on the sea and then breaks off
as a large slab – the large volume of
compressed air within its innards giving
it added buoyancy, in addition to the
lighter fresh water ice floating easily on
the heavier sea water. An iceberg has
just taken birth – a giant floating piece
of a glacier. And then, it starts to move,
almost imperceptibly – sometimes just
a few feet a day. Though generally ice
shelves extend only a few km into the sea,
in Antarctica, the Ross Ice Shelf extends
over 800 km over the ocean before
its edges break off and form icebergs.
Eventually, when it encounters warmer
weather, the floating berg starts to melt.
When this happens, huge chunks of the
berg break off and plunge into the water
becoming floating islands of ice. The
melting also releases large volumes of
trapped compressed air, and air bubbles
breaking out create the characteristic
fizzing sound of bergie seltzer.
Among the first to gain insight into
bergie seltzer was Peter Scholander, a
well-known northern scientist. Nearly
twenty years ago, he co-authored an
article that described the pressures inside
air bubbles locked within glacier ice. His
measurements showed that the pressure
could range from about one atmosphere
(1 kg/cm2) to more than 20 atmospheres.
special feature
Glacier ice can contain huge numbers of air
bubbles, which give the ice a cloudy appearance.
Also, the stripes and different coloured layers in
icebergs represent different layers of snowfall and
the weather conditions under which the snow
fell. European scientists working in Antarctica
have drilled down to the bedrock of glaciers and
recovered ice cores that reveal layers of ice formed
by compressed snow, which can be counted much
like the rings on trees. If it is very cold then a light
open layer with much trapped air will be formed,
forming a paler or white layer. The darker, bluer
layers come from snowfall in relatively warm or wet
conditions when little or no air is trapped in the layer.
What about the proverbial ‘tip of the iceberg’?
Everyone knows that most of an iceberg lies under
water, but most don’t know that the amount
beneath the surface varies from about 50% to 99%.
The cause of the variation is largely in the amount
of air that is trapped in the ice, thus affecting its
buoyancy. An average iceberg will be about 8090% beneath the surface. Very low-lying pieces
of ice, of whatever size in the water, are known as
“growlers.” These often have a green tinge to them.
It is these bergs that present a hazard to shipping
with the small amount visible above the water and
the dark colour making them especially difficult
to see and therefore markedly dangerous when
they float, big and silent, into the path of a ship.
The continuous crackling and fizzing sound of an
iceberg also has another name: ice sizzle. This sizzling
sound made by air bubbles breaking out from the
melting ice is similar to that made by soft drinks
but louder. It is louder because air bubbles formed at
many atmospheres of pressure are released during the
melting. Part of the noise may come from the bubbles
when they come in to close contact with the ice surface.
However, much of the noise is just the escaping air
under high pressure. Nevertheless, hydrophones
placed near melting icebergs have enabled U.S.
Navy scientists to conclude that bergie seltzer could
be detected with sonar, perhaps 100 miles away.
This sizzling icy giant may burp occasionally, but
an iceberg glistening under a bright sun is also a
spectacular sight. Sunlight penetrating the ice reflects
off its inner surfaces giving a whole variety of effects
and colours from white through a range of vivid blues,
creating one of the most magnificent sights in nature.
Does this sizzling, burping giant have any practical
use? People have attempted towing smaller bergs
to the shore in the Polar Regions to augment their
fresh water supplies from the melting ice! This is not
surprising given the fact that only about 1% of the
world’s water is available to humans. Almost 70 percent
of the world’s fresh water is locked up in permanent ice
fields that cover about 10 percent of the world’s land
surface. If all this ice melts, many of the world’s major
cities would be under water from rising sea levels!
Want to hear bergie seltzer? All you need is a glass of
water and an ice cube. Drop the ice cube in the water
and put your ear to the rim of the glass. The steady
fizzle you hear is bergie seltzer. n
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79
It might be hard to believe but air compressors
have been around for thousands of years. The
earliest known compressors were bellows, used
to blow compressed air into furnaces to stoke
up the heat, thereby allowing ancient man to
produce stronger and better metals for tools
and weapons. Following the invention of steam
engines, they became a popular method to power
an air compressor; then IC engines began to be
used as a power source for operating reciprocating
piston-type air compressors. Later, as larger
industries were established, they demanded
more efficient compressors capable of running
with minimal maintenance and for longer
periods. A rotary air compressor was the answer.
Both these types of compressors continued to
evolve over time and today, they are both highly
efficient and technologically well advanced.
Oil-Free
Screw Air
Compressors
Conventional reciprocating air compressors though
have certain innate limitations; most notable
being that the oil used for lubrication is carried
along with the compressed air. Filtering removes
much of the oil but not all. For example, pre-filters,
high efficiency coalescing filters, and activated
carbon filters remove trapped oil to a great extent.
But these filters themselves have characteristic
limitations. For instance, above 20°C, coalescing
filters do not remove fine oil vapours, leaving very
fine particles of residual oil in the form of aerosols;
and activated carbon filters are not usable at
filtration temperatures above 40ºC because the
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research innovation
carbon then absorbs the oil vapor, gets
saturated, and becomes ineffective.
And, filtration itself raises another
problem: safe disposal of used filters to
avoid environmental contamination.
Notwithstanding the environmental
issue however, there are several
industrial applications that require
compressed air that is absolutely oil-free.
Food and beverage, pharmaceuticals,
electronics,
automotive
painting,
textiles, paper and cosmetics are typical
examples. These applications demand
wide operating temperatures of 0-45°C,
stringent air purity standards higher
than ISO 8573-Class I, high levels of
safety, eco friendly operation and some
more. Even the most advanced filtration
technology falls short of meeting such
exceptional standards of air purity.
Plainly, lubricated compressors were
no answer. It required a radically new
technology of air compression. Enter
oil-free screw air compressors. This
inventive machine uses no lubricating
oil in the compression chamber and
hence delivers compressed air with
practically no trace of oil. Additionally,
because of the continuous sweeping
motion of the screws – two meshing
helical screws, known as rotors, driven
by a pair of timing gears – there is very
little pulsation or surging of flow, which
occurs with piston compressors. Screw
compressors thus deliver smooth, pulsefree compressed air. They also tend to be
compact and run smoothly with minimal
vibration. Since they also employ a more
efficient compression system, they
not only reduce energy costs but also
enable precise adaptation to end-user
requirements based on careful study
and analysis of their critical processes
and customizing with a controlled,
total compressed air system, thereby
also improving their productivity.
Despite all its apparent advantages, oilfree screw air compressors continued to
face technological and manufacturing
challenges, especially with regard to
the problem of overheating due to
the absence of lubricating oil in the
compressor chamber. Furthermore,
despite being oil-free, there was still
the need for filtration as hydrocarbons
and other contaminants ingested from
the ambient air required to be removed
prior to the point-of-use. All this began
to affect their popularity to some
extent. However, this also prompted
a new development: oil began to be
injected into the compression cavities
to not only aid sealing but also provide a
cooling sink for the heat of compression.
In this so-called ‘oil-flooded’ rotary
screw compressor, the oil was then
separated from the compressed air,
cooled, filtered and recycled. The
injected oil not only helped in lowering
the compression temperature but
also captured extraneous particulates
from the incoming air, thus effectively
reducing the particle loading of
subsequent air filtration. Having thus
overcome the initial problems that oilfree compressors faced, there was a shift
from oil-free to oil-flooded compressors,
Even the most advanced filtration technology falls short of meeting such exceptional
standards of air purity. Plainly, lubricated compressors were no answer. It required a
radically new technology of air compression. Enter oil-free screw air compressors!
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81
seals and high-performance Viscoseals
at suction and discharge rotor ends,
an ingenious process of PTFE and PFA
(Teflon) dry lubricant coating on carbon
steel rotors, an efficient helix-angled
timing gear and robustly designed cupronickel intercooler and after cooler heatexchangers offering superior corrosion
resistance and finally optimally designed
capacity control valves, all ensure not
just high efficiency but safety, durability,
easy maintenance and low operating
cost. Compression is also very efficient
on account of the precise clearances
maintained between the helical rotors
and the compression chamber, thanks
to the unique eta-V profiles designed by
Elgi. This rotor design reduces pressure
losses and increases stage efficiencies,
leading to an overall increase in adiabatic
efficiency. Only a handful of companies
in the world have this design capability.
It is to be noted however, that though
the machine is termed an oil-free
which
then
gained
popularity.
But the need for a completely oil-free
compressor still remained. This was felt
keenly in industrial applications where
even traces of oil in process air could be
disastrous. For instance, even minute
particles of oil in precision electronic
circuitry or critical semiconductor
components can play havoc with
electronic gadgets. Lube oil traces in
processed food and beverages mean
serious health risks. Pharmaceutical
applications demand pristine air too. It is
the same with paper mills, textiles, highgloss painting of automobiles and many
others. While Western countries had
strict regulations governing the purity
of air used in such critical applications,
Asian countries including India and
China had less stringent rules. But it
was only a question of time before they
too fell in line. And, although industries
continued to rely on filtration to get rid
of the entrapped oil, complex filtration
equipments added to the cost, created
air pressure drops and still did not
deliver 100 % oil-free air. At Elgi, this
presented a situation ripe with potential.
Elgi embarked on developing the oilfree screw air compressor by obviating
the need for oil as a medium to carry
away the heat of compression. By early
2005, the first prototype was assembled
and tested. And by early 2008, a test
compressor was commissioned at a user’s
facility for validation. Next year five
more were commissioned at different
locations. These models completed
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10000 hours of validation. Regular sales
began by early 2011. Today, Elgi’s in-house
oil-free technology with inter-cooler has
been validated in demanding industrial
applications for over 150,000 cumulative
hours. The fully packaged Elgi-NE
series has models with high volumetric
efficiency that deliver from 500 to 1800
cfm (cubic feet per minute) and pressures
of up to 10 bars (kg/cm2.) Incorporating
superior safety norms, these models have
not only low energy losses and low air
outlet temperatures but are also energy
efficient and compact. They employ
two-stage compression with external
water jacket inter-cooling, an unique
eta-V profile rotors enabling high swept
volume, low operating noise and low
vibration achieved by combining radial
roller bearings and with 4-point axially
loaded ball bearings. Innovative features
like carbon impregnated SS air seals,
helical grooved non-contact bronze oil
screw compressor, it applies to only
the screw chamber that forms the air
compression cavity. Oil is nevertheless
used in the machine – to lubricate a
slew of components like the capacity
control valves, air-end bearings, the
timing gears and the airend stage gear.
So even though the rotors and the screw
chamber do not use any lubricating
oil, there is nevertheless an oil circuit
comprising of oil pump, cooler, filter,
and oil sump. Similarly, there is also
a water circuit that supplies cooling
water to the intercooler, after cooler,
and the 1st and 2nd stage airends.
For Elgi, this development has been
a rewarding experience. Industry
watchers have it that globally, Elgi is
one of only 5 corporate companies to
design and manufacture oil free air-ends.
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83
Fuel
Cells
Fuel cells have been grabbing the
headlines over the past several years for
all the right reasons. NASA has used them
to meet power demands on their various
space missions. Since as early as 1966,
fuel cells have provided electric power
and drinking water on all U.S. manned
space flights. They have been used
successfully in automobiles like cars and
buses by some of the world’s leading auto
manufactures including BMW, Hyundai
and Nissan – in the so-called nextgeneration automobiles. By 2015, major
automakers foresee mass-produced fuel
cell vehicles on the roads – mainly in
the US and Europe. When that happens,
fuel cell hybrid vehicles will reduce
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greenhouse gas emissions by 50 percent
or more and emit nothing but water
from the tailpipe. Because fuel cells
operate without combustion, they are
virtually pollution free. What’s more,
since fuel cells have no moving parts
either, these vehicles guarantee a smooth,
quiet ride. Little wonder many leading
auto
manufactures
are
working
assiduously on technologies and ideas
that will enable them to transition
their vehicles from internal combustion
engines to fuel cells. Demonstration fuel
cell vehicles have been developed with
a driving range of more than 400 km
between refueling – a process requiring
barely 5 minutes.
research innovation
What are fuel cells? A fuel cell is a
device that converts chemical energy of
a fuel directly into electricity through
a chemical process involving the fuel
and an oxidizing agent. Hydrogen is the
most commonly used fuel and oxygen
is mostly used as the oxidizing agent.
Fuel cells are different from batteries in
that they require a constant source of
fuel and oxygen to run; and as long as
these inputs are supplied, fuel cells can
produce electricity almost continuously.
Furthermore, since the fuel is converted
directly to electricity, a fuel cell can
operate at much higher efficiencies than
conventional IC engines, extracting
more electricity from the same
amount of fuel. Efficiencies as high as
90 percent have been achieved with
fuel cell composite units that use both
the generated electricity and the byproduct heat to meet thermal energy
needs like heating and air-conditioning,
in the process turning potential waste
into useable energy. Today, there are
commercial fuel cells that power
automobiles, buses, cell phone towers
and even some airport terminals.
What really goes on inside a fuel cell? As
stated, a fuel cell is an electrochemical
device that combines hydrogen fuel
and oxygen from the air in a chemical
reaction to produce electricity. Heat
and water are the byproducts. A fuel
cell is made up of an anode (a negative
electrode that releases electrons),
a cathode (a positive electrode that
accepts electrons) and an electrolyte in
between. Hydrogen is supplied to the
anode and oxygen or air to the cathode
resulting in two chemical reactions
occurring at the interfaces of the three
different segments. As hydrogen – in
this case, the fuel – flows externally
into the anode, a catalyst layer on
the anode oxidizes the fuel (releasing
electrons), splitting the hydrogen
The electrolyte in the centre allows only the protons to pass
through it and reach the cathode. Since the electrons cannot
pass through the electrically insulating electrolyte, they are
forced to take an external circuit forming an electric current
atoms into positively charged hydrogen
ions or protons and negatively charged
electrons. However, the electrolyte in
the centre allows only the protons to
pass through it and reach the cathode.
Since the electrons cannot pass through
the electrically insulating electrolyte,
they are forced to take an external
circuit forming an electric current. This
current of electrons, in the form of a
direct current or D.C, constitutes the
power output of the fuel cell. Secondly,
as oxygen flows externally into the
cathode, another catalyst layer helps the
arriving protons to be reunited with the
electrons – which have traveled through
the external circuit – in a process called
reduction (causing a gain of electrons)
and the two then react with the supplied
oxygen to produce pure water and
heat. Generally, individual fuel cells are
sandwiched together into a fuel cell stack
to increase the total electrical output.
In installations where A.C is required,
a power inverter is used to convert the
electricity from D.C to A.C. And where
natural gas, instead of hydrogen, is used
as the fuel, a fuel processor reforms
the natural gas to hydrogen gas to feed
the fuel cell stack. Fuel cells can be
combined in series or parallel circuits,
the series circuit yielding higher voltage,
while parallel allows a higher current.
Surprisingly, for all its modern, hitech aura, fuel cells have been known
to science for a century and a half.
The principle of the fuel cell was first
discovered by a German scientist named
Christian Friedrich Schönbein in 1838.
Based on his work, the first fuel cell was
demonstrated by a Welsh scientist and
barrister Sir William Robert Grove in
February 1839 in a scientific magazine
of the time. The ‘Grove Cell,’ as it came
to be known, used a platinum electrode
immersed in nitric acid and a zinc
electrode in zinc sulfate to generate
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85
The Timeline
of the Fuel
Cell
Surprisingly, for all its modern, hi-tech aura, fuel cells have been known to science
for a century and a half
about 12 amps of current at 1.8 volts.
The ‘Grove Cell,’ that later acquired the
moniker ‘Gas Battery’ in the nineteenth
century, spurred research and the testing
of further theories. The gas battery came
to be called a ‘fuel battery’ and later still
a ‘fuel cell,’ though the exact details of
the term’s origin are still unclear. Fast
forward to 1955, when Thomas Grubb, a
chemist working for the General Electric
Company (GE), modified the original
fuel cell design by coming up with a
sulphonated polystyrene ion-exchange
membrane as the electrolyte. Three
years later another GE chemist, Leonard
Niedrach, devised a method of depositing
platinum onto the membrane. This
served as a catalyst and speeded up the
reactions of hydrogen oxidation and
oxygen reduction. The innovation led to
the development of the ‘Grubb-Niedrach
fuel cell’. Traditionally, the cathode has
been made of nickel. Developments
and improvements continued and in
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1959, British engineer Francis Thomas
Bacon successfully developed a 5 kW
stationary fuel cell. The same year a 15
kW fuel cell was developed that used
potassium hydroxide as the electrolyte
and compressed hydrogen and oxygen
as fuel and reactants. More than thirty
years later, in 1991, the first hydrogen
fuel cell automobile was developed by
Roger Billings. Today, commercial fuel
cell models of 500 kW and above are in
use in hospitals, universities and large
commercial buildings as stationary
fuel cell system in co-generation
power plants. In a bid to achieve cost
advantage that would allow fuel cells to
compete favorably with current market
technologies, including automotive
IC engines, many companies are now
working on techniques to reduce costs
in a variety of ways including reducing
the amount of platinum needed in each
individual cell. Some fuel cells, in fact, do
not use platinum at all as catalysts, but
instead use cheaper materials such as
nickel and nickel oxide. Another approach
has been to reduce the cost of hydrogen
gas, by employing a fuel reformer,
through which the fuel cell can utilize
hydrogen from a number of hydrogen
compounds including hydrocarbons like
natural gas, methanol, propane, and even
biomass. Efforts have also been made to
obtain hydrogen by separating water in
an electrolyzer, or by extracting it from
a compound that contains no carbon,
such as ammonia or boron compounds.
However, hydrogen gas can only be
stored at very low temperatures or
under very high pressure, both being
not only impractical but also fraught
with danger. Ongoing efforts to store
hydrogen safely have produced some
spectacular results.
Continuing research and innovation has
led to the development of a plethora
of fuel cell types – mainly depending
In addition to offering operational and cost benefits, it also minimizes environmental
impact significantly. Clearly, fuel cells are poised for a big technological leap into the
future
on the type of electrolyte used and the
temperature of operation – employing
an array of technologies and meant
for a myriad of applications. The
following are some of the main types:
• Proton exchange membrane – using
a solid polymer membrane as an
electrolyte.
• Direct methanol – using unreformed
liquid methanol fuel rather than
hydrogen.
• Phosphoric acid – employing liquid
phosphoric acid as an electrolyte with
a platinum catalyst.
• Solid oxide – using a solid ceramic
electrolyte
• Molten carbonate – using a molten
alkali carbonate mixture as the
electrolyte
• Alkaline – electrolyte solution of
potassium hydroxide
Fuel cells have found application in
various other fields too. Aviation is
one example. In 2003, the world's first
propeller-driven
airplane
powered
entirely by a fuel cell was flown. The fuel
cell had a unique stack design, which
allowed the fuel cell to be integrated
with the aerodynamic surfaces of the
plane. Then in 2008, Boeing researchers
conducted an experimental test flight of a
manned airplane powered only by a fuel
cell and lightweight batteries. The fuel cell
used had a proton exchange membrane
and a lithium-ion battery hybrid system
to power an electric motor that was
coupled to a conventional propeller.
German and Italian navies use fuel cells
in their submarines that allow them to
remain submerged for weeks without
the need to surface. The latest, an
ultra-modern non-nuclear sub marine
developed by a German naval shipyard,
uses nine PEM (polymer electrolyte
membrane) in its fuel cells, providing
between 30 kW and 50 kW of power from
each. The completely silent vessel has a
distinct under water advantage, and is
found to be a good alternative to nuclearpowered subs. More than 2,000 fuel cell
powered forklifts are being installed
and operated at warehouses across
the United States by multi-national
companies. Along with these newfanged applications, fuel cells have also
made inroads into notebook computers
for applications where AC charging may
not be available for weeks at a time.
They are also used in portable charging
docks for small electronic devices like
a belt clip that charges cell phones,
and even in small heating appliances.
The sustained efforts of the U.S.
Department of Energy have provided a
fillip to fuel cell technologies, facilitating
significant progress toward overcoming
many of the challenges to widespread
commercialization.
These
include
not only reducing the cost but also
improving the durability of fuel cells and
improving technologies for producing,
delivering and storing hydrogen. And
since fuel cells employ a clean energy
conversion technology, in addition to
offering operational and cost benefits,
it also minimizes environmental impact
significantly. Clearly, fuel cells are
poised for a big technological leap into
the future.
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87
Guniting
Guniting. Puzzled by the pronunciation? Start with ‘gun’ and end with ‘iting’ as in ‘sitting.’ All right, but
what on earth is guniting? No, it has nothing to do with arms and ammunition. Yet, it is derived from
the word ‘gun.’ Not the lethal variety to be sure, although it does fire. Here’s the clincher. It fires cement; actually cement mortar!
And the energy for firing doesn’t come
from gun powder but from compressed
air. That’s right. Compressed air and a
specially designed air-actuated pump
that can handle sand and grit propel a
dry pre-mix of cement and sand into a
nozzle and prior to ejection is mixed with
water supplied through a separate pipe
attached to the nozzle. The controlled
quantity of water forms mortar with the
right consistency to plaster a surface like
a wall when the mortar is projected onto
it. At the heart of guniting is compressed
air. Portable diesel engine-powered
air compressors mounted on a trolley,
supply the compressed air required at
the work site. Air delivery can vary from
250 cubic feet per minute (CFM) to 600
CFM or more and the working pressure
anywhere up to 10 bar, or roughly
ten times the atmospheric pressure.
Gunite or guniting is a specific term
that refers only to the dry-mix process
in which the dry cement mortar mix is
propelled through a hose to the nozzle,
where water is injected just prior to
ejection. However, there is a general term
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that refers to the process of spraying
of concrete or mortar accomplished
through either a dry or a wet mix of all
the ingredients. That all-inclusive term
is Shotcrete. Wet-mix shotcrete involves
pumping a previously prepared mixture,
typically ready mixed concrete made
up of appropriate proportion of cement,
sand, stone aggregate and water, to the
nozzle. Compressed air is supplied at
the nozzle to impel the mixture onto
the receiving surface. Since 1967, the
American Concrete Institute has been
using the term to describe all sprayed
concrete or mortar. Later, shotcrete
became the official generic name of
the sprayed concrete process, whether
it utilizes the wet or the dry process.
But back to guniting. Guniting was
invented in the early 1900s by American
taxidermist Carl Akeley, who used
the technique to fill plaster models of
animals. He blew dry material out of a
hose with the help of compressed air,
injecting water at the nozzle just before
it was released. He later applied this
method to patch old buildings with
concrete, and later still, this was adapted
by masonry workers. In 1911, Akeley
obtained a patent for his invention,
which he called the “cement gun,” and
“gunite,” the material the gun deposited
on a surface. So the wet mortar or
concrete blasted by pneumatic pressure
from a gun is termed “gun”-ite, and the
equipment used is called the “cement
gun.” That makes the term “gunite”
a noun (product name) rather than a
verb (action). And “guniting” means
blowing dry material out of a hose with
compressed air, wetting it as it is released
and impinging the same on to a surface.
The term also refers to the procedure
used to patch weak parts in old buildings
or other repair applications where the
stop-and-go flexibility of gunintig is so
useful. Interestingly, there is a certain
twist in the tale of guniting. Akeley, who
invented the technique and coined the
original term “gunite,” had promptly
trademarked his invention and the term,
in 1909. Subsequently, the term became
the registered trademark of Allentown
product focus
Equipment, the oldest manufacturer of
gunite equipment. Other manufacturers,
who followed later, were thus compelled
to use other terminology to describe the
process such as pneumatic concrete,
guncrete, etc. However, those old terms
have since been replaced by guniting.
Let’s now look at the technique in some
detail. Generally, the dry mixture is
blown through a hose to the nozzle,
where it mixes with the injected
water. But though water and the dry
ingredients meet inside the nozzle, their
thorough mixing, which is so essential,
is not completed in the nozzle. That
happens as the materials impinge on
the receiving surface. This process is
effectively regulated and accomplished
through manipulation of the nozzle.
The personnel handling the nozzle
therefore requires to be highly skilled,
especially in the case of thick or heavily
reinforced sections, although coarse
stone aggregate is seldom used with the
dry-mix process of guniting. Obviously,
the nozzle is an important piece of
equipment in guniting. The specially
designed nozzle is fitted inside with
a perforated manifold through which
water is sprayed under pressure and
mixed with the pneumatically propelled
jet of sand and cement. The high air
pressure produces a high nozzle velocity
of about 90 to 120 metres per second.
This results in good compaction. The
nozzle operator controls the nozzle by
hand on small jobs, like constructing a
small swimming pool, on larger work
however, the nozzle is sometimes held
by mechanical arms and the operator
controls the operation by a hand-
held remote device. These mechanical
nozzle manipulators are some times
called spraying robots. Understandably,
guniting operation is challenging and
can be potentially dangerous. There are
number of high-pressure hoses carrying
compressed air, water, and materials and
there is a risk of a blast in any of these and
also sometimes in the nozzle itself, despite
high quality standards in equipments’
manufacture and periodic checks while in
operation. Safety of operators is therefore
an important concern. Personal protection
equipment against dust emissions, special
working suits, helmets, masks, gloves,
and protective glasses are generally used
during guniting or shotcrete operations.
Basically, the method involves first placing
the dry ingredients in a hopper, metering
through a distributor to ensure right
proportions, and then conveying the
material pneumatically through the hose
to the nozzle where it is projected at a high
The specially designed
nozzle is fitted inside with
a perforated manifold
through which water is
sprayed under pressure
and mixed with the
pneumatically propelled
jet of sand and cement.
The high air pressure
produces a high nozzle
velocity of about 90 to 120
metres per second
velocity on to a surface. The operator
handling the nozzle controls the addition
of water at the nozzle. As stated, since
the complete mixing of water and the
dry mixture is accomplished as the
mixture hits the receiving surface,
the water content can be adjusted
instantaneously by the nozzle operator,
allowing more effective placement
even on overhead surfaces or vertical
applications. It is important to note that
the placement and compaction happen
at the same time due to the force with
which the material is projected from the
nozzle. Concrete produced by guniting
is reinforced by steel rods or steel mesh
as in conventional concrete. This process
lends itself very well to tunneling
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89
1. Material is gravity-fed from hopper to empty pockets of the
rotary feed wheel (feed bowl) below.
2. The rotary feed wheel, driven by a motor, rotates. The materialfilled pocket is positioned under a compressed-air chamber.
3. Introduction of compressed air lifts the material out of the
pocket and into the material outlet.
4. Dry material is conveyed in suspension through the hose to the
gunite nozzle where water is introduced to the dry material.
operations or to reinforce a slope. In
this case, steel or synthetic fibers are
employed as reinforcement and also to
stabilize the mortar or concrete mix on a
slope or on the inside contour of a tunnel.
What are the real advantages of
gunintig? From a structural point of
view, the high-pressure application
ensures a dense surface of high strength
and low permeability, a strong adhesion
between fresh mortar and an old surface
receiving the high-pressure semi-solid
mix, and better bond between old
concrete and fresh concrete. Despite the
equipment cost involved, the process
is rather economical not only due to
saving in time, but also because it allows
reducing the cement content. The force
of the impact facilitates zero slump of the
material that can support itself without
sagging or peeling off. Guniting is an
especially useful method for repairing
R.C.C. columns and beams, which have
cracked or have exposed reinforcement.
Unlike in the case of poured concrete,
no formwork is necessary. Furthermore,
even intricate shapes can be successfully
constructed or repaired. However, to
gain its full benefits, it is essential
that adequate care is taken in surface
preparation, mix design and the
application process. Though guniting
carried out with adequate care ensures
long service life of structures, it is
essential to observe several precautions
and take additional steps at every stage
in order to obtain the desired results. For
instance, there is a process called silica
fume guniting. Silica fume, when added
to the dry mix, substantially improves
the adhesive and cohesive properties
of fresh concrete or cement mortar by
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creating a dense sticky mix almost devoid
of bleeding. Additionally, silica fume
facilitates overhead repairs, a greater
thickness in a single pass of the nozzle
and superior adhesive characteristics.
Another method to enhance durability
of gunited surfaces is application of
epoxy coatings over the finished surface.
To ascertain the quality of guniting,
finished
structures, segments
or
components are tested for soundness,
homogeneity and strength. For this,
cores are drilled from the finished and
cured surfaces. Non-destructive tests
include sounding, rebound hammer
test and ultrasonic pulse velocity tests.
Sometimes, test panels are periodically
cast during guniting for quality testing.
Despite the equipment
cost involved, the process
is rather economical not
only due to saving in time,
but also because it allows
reducing the cement
content
As stated, compressed air is at the
heart of the guniting process. Since
it is used in such diverse applications
like tunneling, heavy civil construction
like dams and bridges, shielding and
reinforcing slopes and steep gradients
and such other work, air compressors
used in guniting operate in some of the
most severe and rugged environments
– on hot, dusty and rough terrains and
exposed to the elements round the
clock. These compressors therefore are
built to withstand such severe working
conditions. Elgi has been catering to this
segment with packaged, diesel enginepowered air compressors mounted on
trolleys. These mobile units serve very
well on remote and rugged work sites.
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THE ELGI MAGAZINE
91
Auto
Car Wash
With the vast number of vehicle models
and brands now available to consumers all
over and with soaring automobile sales,
vehicle owners have been increasingly
demanding professional servicing and
faster service turnaround times. Vehicle
servicing today is both a demanding
as well as a burgeoning business.
A modern garage or service centre
requires a diverse range of equipments.
Automotive
service
equipments
therefore span a wide spectrum designed
to provide a slew of services from vehicle
lifting, washing, body shop, testing and
diagnostic equipments to myriad tools
and accessories. These are designed to
carry out specific tasks and meant for a
specific type of vehicle. While most of
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these equipments are meant to service
the vehicle, repair or maintain the engine,
and generally keep the mechanical
parts ship-shape, there is one piece of
equipment that merely keeps a vehicle
gleaming and looking good. That is the
automatic car washer. Ever since two
Detroit men opened an ‘automated car
laundry’ in 1914, automated car washers
have found a niche for themselves in
garages, service centres and even petrol
bunks offering driveway washing.
Let’s find out how the system works.
Exterior Rollover Car Wash System
This is an automated system where the
car to be washed is driven inside a bay
and positioned suitably, aligned with
markers on the floor. Once the system is
switched on, the car-wash equipment in
the form of a trolley or gantry straddling
the car moves over it on twin tracks
positioned on either side, performing
specific functions sequentially. The
operation begins with pre-rinsing where
high-pressure water sprays ejected from
multiple nozzles placed strategically on
the moving equipment wash off dust,
dislodge dirt and wet the car thoroughly.
Next, detergent shampoo introduced by
an injector at around 1 to 5% into the
water is sprayed through the nozzles
as the gantry makes another pass
over the car from one end to the other.
These cleaning solutions are specially
formulated to not only loosen and
product focus
eliminate dirt and grime but also impart
an after wash glow to the surface. Once
the water and shampoo mix is sprayed
on the car, exterior-rollover circular
brushes or scrubbers spinning at 100500 RPM and made of either cloth strips
or bristles of polyflex strings roll over
the car. Vertically placed brushes move
on either side while a single horizontal
brush on the top scrubs the upper
surfaces of the car. Thus the two vertical
brushes wash the front, sides, and rear
and the roof brush washes the front,
bonnet, roof and rear. The brushes follow
the contour of the vehicle no matter how
it is parked in the bay and can make
multiple passes. The brush speed and
pressure are continuously monitored
by a control system. Foam from the
specially designed shampoo produced by
the right proportion of soap and water
and the wraparound brushes ensure that
every area of a vehicle’s surface from the
front bumper to the rear is gently yet
thorough cleaned. In some cases, the
cleaning water jet and the shampoo just
precede the rollover brushes, all working
during a singe pass. Separate sets of
spinning tyre-brushes positioned for
each wheel now move toward individual
wheels guided by sensors and then
advance to give the tyres a quick scrub to
remove dirt and grime and retract. This
is followed by a final rinse with high-
Rollover Car Wash System is an automated system where the car to be washed is
driven inside a bay and positioned suitably, aligned with markers on the floor
Rinsing with Shampoo
Brush Wash
Smart Wash
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Brush wash and Disk Brush wash
Wax Spray
Dryer - Two passes
The system supports the
complete range of cars
and SUVs and each wash
cycle takes any where from
fifteen to twenty minutes
In the beginning, meticulous car
owners avoided mechanized car
washes because of the risk of
damaging the finish. Older automatic
washers built prior to 1980 used
brushes with soft nylon bristles that
left brush marks on the vehicle’s
paint. But with modern paint finishes
and improved car washing processes
that utilize brushes made of either
cloth or closed cell foam, car washing
now is far less likely to harm a car’s
painted finish. Closed cell foam
brushes, in fact, provide a gentle
polishing effect that leaves an after
shine on the vehicle’s surface.
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pressure water streams to wash off the
foam and dirt. For the final rinse some
car washes use soft water that has been
filtered of chlorine and passed through
semi permeable membranes to produce
highly purified water that does not leave
spots. The water spray and brushes
are now switched off and retract and
the floor mounted trolley now moves
over the car with blasts of air ejected
from the sides and the top from high
capacity blowers located inside. This
touch-free drying system enveloping
the vehicle rapidly dries the vehicle
surface and the car is ready to move
out. In some cases heated air is utilized
to ensure thorough drying. The system
supports the complete range of cars and
SUVs and each wash cycle takes any
where from fifteen to twenty minutes.
The wash water needs to be effectively
filtered and conditioned to remove
impurities, dissolved minerals and salts.
Filtering features include activated
carbon pre-filter and low-micron
cartridge style filters, and commercial
resin-based
water
softeners
are
employed to provide conditioned soft
water. Expensive models use reverse
osmosis (RO) systems that efficiently
filter the water at the molecular level
for a premium, spot-free wash. Used
wash water is sometimes recycled back
to a storage tank after passing through
a filtration system. Only clean, nonrecycled water is used for the rinsing
though. Advanced software-controlled
wash programmes coupled with
strategically placed photo eye sensors
provide a reliable means of actuating
the water jets and air streams to match
the length and contours of the vehicle.
This customizing of the travel distance
to the size of the vehicle ensures that
wash products are applied to the
vehicle and not wasted on the floor.
A wholly owned subsidiary of
Elgi Equipments namely, ATS Elgi
manufactures a wide spectrum of
automotive service equipments with a
product portfolio that covers almost the
entire range of equipments required
in a modern garage, catering to both
organized garages as well as to a network
of OEM-controlled service centres. ATS
Elgi either manufactures or deals in
garage equipment under a wide range of
verticals.
n
engineering solutions
Engineering
Solutions
Elgi , Elgi Sauer and ATS Elgi Products
Eco-Friendly Alternative
Elgi has developed a new series of electric powered portable
screw air compressors – the E75 series. Following the launch
of the 60 HP model, Elgi has designed and customized a new
series based on end user needs. This series is designed to
reduce operating expenses and offer customers higher returns
on their investment, especially in the construction & mining
industries. The compressors in the new E75 series feature Elgi’s
unique energy-efficient N-profile airends. Their reliability
makes them suitable for both standard applications such as
breakers and tools in road repair and specialized uses such as
sand blasting, pigging, drilling and optical fibre blowing. These
electric powered portables are ideal for work environments
where quiet and emission-free operation is required.
The E75 portables are rugged and highly manoeuvrable.
The new units can function in all ambient temperatures
and dusty environments. A high performance pre-filter
foam supports the canopy to arrest dust before it enters
the compressor. The compressors are also provided with
a height- adjustable drawbar and parking brake. They are
designed with a closed base-frame bottom to hold oil-spills.
Presently there are three models in the E75 series, with working
pressures of 7, 9.5 and 10.5 bar respectively. And very shortly Elgi
will be launching a whole new range of electric powered portables
to cater to the needs of the construction and mining industries.
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95
Essentials Encapsulated
For many years Elgi has met diverse industrial needs with the Horizon and Global
series of efficient rotary screw compressors which are known to be very user friendly.
Elgi’s encap series compressors are an addition to this family of compressors.
A traditional compressed air system comprising individual functional components
can be replaced entirely with a single encap series compressor. The encap series
compressor features Elgi’s unique encapsulated airend, with all functional systems
such as intake, compression and discharge system integrated in a common housing.
This arrangement makes the compressor more compact than any other similar
compressor on the market. The unique design of encapsulated compressors allows
ease of access to all standard components for servicing. All standard components are
positioned at the front of the compressor thus allowing immediate access by simply
removing the panel.
The separator element is also conveniently located for easy servicing. There is no
tubing to disconnect which prevents leakages and saves service time. The amount
of oil carried over is minimised. It also eliminates most of the external piping. This in
turn minimizes leakages and pressure losses.
Encapsulation reduces the noise level of the compressor considerably – as low as 61
dB. The main components such as the motor and airend are mounted onto a sturdy
and vibration-free base plate that absorbs vibrations and reduces noise levels. The
compressor is controlled through Elgi’s Neuron controller, with easy-to-use menus,
backlit display, a message box, a fault log, special functions and an emergency
warning.
The new encap series of compressors are designed to operate at ambient temperature
as high as 45OC. The greater airflow generated by the electric fan provides for very
efficient cooling even during continuous use and in higher ambient temperatures.
Elgi’s encapsulated compressors are available in a wide range from 2.2 kW to 15 kW
Rugged and Reliable
Elgi has developed a new diesel powered screw air compressor, the DS 1200-325. The skid compressor has been designed entirely
by Elgi for down-the-hole (DTH) drilling in construction, mining and water-well industry. It is built for profitable and safe drilling
in all geological formations. It drills to a maximum depth of 1200 feet at fairly high speeds.
It has an effective output of 1200 cfm for flushing and a drilling pressure of 325 psi. The skid compressor is powered by Cummins
engine carrying an international warranty. The rotors use a unique eta-V profile airend that are engineered for improved
efficiency. Using this energy-efficient airends, the compressor offers increased drilling efficiency and improved penetration rates.
The product meets ASME requirements and complies
with international safety standards. Built and tested
to ISO 9001 quality standards, the compressors
are designed with a vertical air oil tank for better
separation and compactness. Flange joints arrest the
compressor leaks. The genuine compressor oil filters
deliver clean oil that ensures high performance of
the compressor. Large doors provide easy access to
serviceable components. That simplifies routine
maintenance and reduces downtime and service cost.
A centralised control panel with in-built HMR and
tachometer displays all operating data.
As an optional feature, the compressors are also
available with remote monitoring system.
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Global Series (90-160 kW)
These global series compressors represent a giant leap in design
and performance, with each component designed for reliability
and ease of maintenance. The new version is available in 90-160
kW power range. Aesthetics and overall efficiencies including
significant reduction in noise levels have been incorporated in
this new model along with improved features like low oil carry
over, efficient moisture separation, user-friendly advanced
Neuron II controller etc. Featuring a compact footprint and with
a maximum noise level of just 75 dBA, these are among the most
efficient and silent machines in the market.
The compressors are fitted with Elgi’s own energy-saving
eta-V profile airends, which have a unique screw profile and
low specific power consumption. The compressor comes with
a custom designed moisture separator to handle high humid
compressed air outlet from after cooler. This centrifugal type
moisture separator removes over 99% of moisture by impact
and centrifugal action with minimal pressure drop resulting in
corrosion-free, longer life of end use equipments and less load
on the dryer. The new global series compressors are fitted with
a unique three-stage air-oil vertical separator tank that enables
separation of oil in three stages delivering oil-free air with less
than 1 ppm of oil. Fitted with highly efficient coolers, these
compressors are designed to run at high operating temperatures.
KEEPING ABREAST WITH NEW CHALLENGES
Elgi Equipments has been associated with Indian Railways since 1968 and has successfully partnered with them in developing
indigenous capabilities for electric and diesel locomotives, and EMUs. Elgi has also been continuously working to upgrade the
compressor products it has been supplying to Indian Railways to meet the new challenges of reduced down time and longer
maintenance cycles due to the higher operational utilization of the rolling stock. The Elgi upgraded expressor for the diesel
locomotives was one such product – introduced years back with cooperation and guidance from RDSO and the Railway Sheds.
This was achieved by redesigning the compressors for maintainability and serviceability with input from the railway sheds,
using DFEMA Total Quality Management (TQM) approach. Elgi has now upgraded its TRC 1000 MN compressor, which powers
electric locomotives.
Upgraded Single Phase
Compressor
The TRC 1000 MN UG is an upgraded version of the workhorse
compressor TRC 1000 MN that was introduced in the WAP4 and WAG9 locomotives manufactured by Chittaranjan Locomotive Works
(CLW). The TRC 1000 MN UG compressor was developed keeping the
aforementioned objectives. It has longer maintenance intervals and
higher reliability and maintainability than its predecessor due to
the design improvements made in the product. The compressor has
a nominal discharge volume of 1000 lpm at 10.5 bar pressure and is
interchangeable with the existing product. The product has undergone
validation as per Indian Railway procedures.
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engineering solutions
High Capacity Compressors for Electric locomotives
Elgi has developed the RR 20100 CC compressors that have the capability to cater to the needs of single-phase and three-phase
locomotives manufactured by CLW viz., WAP-4, WAP-5, WAG-7 and WAG-9. The need for higher capacity compressors arose when
Indian Railways started introducing the Shatabdi and Duronto trains. The air consumption for these trains increased from 1000
lpm to 2000 lpm due to the addition of air suspension system, pneumatic toilets and doors for passenger comfort. Presently,
three 1000 lpm compressors (two working and one standby) are mounted on deck. Elgi has developed the common compressor
(RR 20100 CC) with a nominal air delivery of 1750 lpm at 10.5 bar pressure and having the same size but lesser footprint compared
to that of the existing 1000 lpm version. The RR 20 100 CC was developed to fit within the existing envelope of the 1000 lpm
compressor. In case of three-phase locomotives, the same compressor can be mounted under slung using wire rope isolators. By
virtue of this, the product will benefit Indian Railway sheds on inventory costs.
Breathing Air Compressor
Elgi Sauer’s quality position in the market for naval compressors are well known.
With the introduction of the unique HP compressor block ‘Tornado’ this quality
and performance is now also available for breathing air compressors.
Elgi Sauer’ breathing air compressors used by the navy can be delivered according
to several shock and vibration standards from simple LRoS rules to highest naval
standards like US Mil Std 901 or German BV0432 and 044.
The heart of each breathing air station is the very robust compressor block
– a block which is designed to withstand highest demands as they occur for
naval applications such as inclination, shock, vibration, high temperatures
and continuous operation. The vertical arrangement of the running gear of
the ‘Tornado’ models WP 3215 and WP 4325 has been adopted from the watercooled WP 5000 compressors, which are used in submarines, frigates and aircraft
carriers. It ensures lowest noise emission and structure borne noise.
Elgi Sauer’s breathing air compressor for navy has everything required for a
complete installation: fully automatic electronic control, noise insulation down
to 72 dB (A), integrated filter, demistor and condensate collecting tank. Filtration
can be delivered according to all international standards such as DIN EN 12021, BS
4275 and BS 4001or US CGA Grade D+E and naval standard FS Grade A+B.
Aviation Compressor
The aviation industry is under considerable pressure to keep the costs down,
yet, at the same time, it is faced with ever-increasing safety demands.
Thankfully, the use of Sauer’s medium and high-pressure compressors can be
of great help in both these areas. The costs of running aircraft fleets can be
minimised by using nitrogen to inflate aircraft tyres, whilst the compressors’
long maintenance intervals (MTBF) enhance this effect. Additionally, the
option of combining a variety of different drive systems as well as the units’
compact design have a further positive effect, allowing the compressors to be
moved around and used inside airport aprons.
Elgi Sauer‘s Passat and Hurricane series compressors with metric flow
(80-120 m3/hr) and pressure range (40-350 bar) are used in this industry.
The compressors provide long operating life with guaranteed availability
of replacement parts (minimum 25 years working life). Robustly designed,
these compressors withstand extreme working conditions (55°C ambient
temperature). They also have a high reliability factor, even with intermittent
operation. Compact design and extreme ease of operation are other key
advantages with these compressors.
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Universal Jig System
ATS Elgi’s Universal Jig System is the perfect choice for fast and precise repairing of all type of accidental vehicles. It’s has a
lifting capacity of 5000 kg with a lifting height of 1550 mm. The Universal Jig on a 5 m bench is conceived according to rational
ergonomic criteria. With this bench, you can repair all types of passenger cars (like unibody, chassis & cabins), light commercial
and 4 WD vehicles. It is even possible to repair a 3 Wheeler or a 2 Wheeler. It is also equipped with wheels allowing you to move
the bench around the workshop. The sliding movement on racks ensures fast and easy positioning of the jigs and clamps on the
anchoring points. Additionally, it allows pulling the column in to a dozen different positions 360° around the bench.
Mc Pherson is a measuring device designed according to revolutionary criteria and it is equipped with doors to quickly position
the device and allows measuring and checking not only the usual points on the shock absorber but also any point on the upper
body.
With the Universal Jig holding and fixing system you can anchor, hold, support and measure a vehicle during body repairs. The
jig system is ideal for repair of chassis without any need of extra attachments. This universal Jig Bench can just repair any type of
crash on any model of vehicle. Thanks to data software which has vehicle data of most of the vehicles present globally including
the model available in India.
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On Car Brake Lathe
All modern vehicles are equipped with brake discs, mostly front and
rear, including trucks. Every brake disc suffers from rust, and to some
extent distortion, due to its material – cast iron. Salt, heat, moisture,
friction, and exposure to chemicals determine the wear and surface
condition of brake discs (rotors). As soon as this reaches a certain
point, brake performance deteriorates. The driver experiences loss
of control, increased vibration and noise while braking.
ATS Elgi’s MAD On Car Brake Lathe eliminates all disadvantages of
cast iron brake discs and the adverse affects of environment and
working conditions on the material by simply and lightly cutting
away the affected surface of the disc at both sides simultaneously.
With two sharp cutting-tips it just removes a few microns. Within 5
minutes the disc is as good as new!.
The disc stays on the vehicle during the job. Only the brake caliper is
take off and replaced by the disc lathe. No special skills are required
– just two bolts to fit the lathe to the car and slide the lathe in to
position, adjust the cutting-tips and push the start button. No
compensating runout or disc thickness variation . No adapters
either; it always fits.
Inverter Spot Welder
ATS Elgi’s spot welder 12500A INVERTER is a water-cooled spot welding
system designed for all car body repairs specially with the latest models
which use High Strength Steels. High quality inverter technology
assures perfect spot welding results.
Gun, arms and other machine parts are water cooled, thus reducing
overheating of the device and keeping performances steady from the
first to the last point. The easy and user-friendly control panel depicts
all operations through icons, allowing easy management of all machine
functions.
The guns line with cooled arms, offering the best solutions to each body
shop worker. The function of the support with that of the gunmetal ring
permits freedom of movement and rotation around the parts. It enables
quick change of spot-welding pliers by means of C-pliers. The C-pliers
provide greater access to number of repair areas on a vehicle.
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