Katharometer Units and Accessories for Non-Corrosive Sample Gases Instruction Manual 6517 and 6518

Instruction Manual
IM/6517–6518_5
Katharometer Units and Accessories for
Non-Corrosive Sample Gases
6517 and 6518
ABB
The Company
GI
STER
Cert. No. Q 05907
As a part of ABB, a world leader in process automation technology, we offer customers
application expertise, service and support worldwide.
EN 29001 (ISO 9001)
We are committed to teamwork, high quality manufacturing, advanced technology and unrivalled
service and support.
The quality, accuracy and performance of the Company’s products result from over 100 years
experience, combined with a continuous program of innovative design and development to
incorporate the latest technology.
E
RE
We are an established world force in the design and manufacture of instrumentation for industrial
process control, flow measurement, gas and liquid analysis and environmental applications.
D
EN ISO 9001:2000
Lenno, Italy – Cert. No. 9/90A
Stonehouse, U.K.
The NAMAS Calibration Laboratory No. 0255 is just one of the ten flow calibration plants
operated by the Company, and is indicative of our dedication to quality
and accuracy.
0255
Electrical Safety
This instrument complies with the requirements of CEI/IEC 61010-1:2001-2 "Safety requirements for electrical equipment for
measurement, control, and laboratory use". If the instrument is used in a manner NOT specified by the Company, the protection
provided by the instrument may be impaired.
Symbols
One or more of the following symbols may appear on the instrument labelling:
Warning – Refer to the manual for instructions
Direct current supply only
Caution – Risk of electric shock
Alternating current supply only
Protective earth (ground) terminal
Both direct and alternating current supply
Earth (ground) terminal
The equipment is protected
through double insulation
Information in this manual is intended only to assist our customers in the efficient operation of our equipment. Use of this manual for
any other purpose is specifically prohibited and its contents are not to be reproduced in full or part without prior approval of the
Technical Publications Department.
Health and Safety
To ensure that our products are safe and without risk to health, the following points must be noted:
1. The relevant sections of these instructions must be read carefully before proceeding.
2. Warning labels on containers and packages must be observed.
3. Installation, operation, maintenance and servicing must only be carried out by suitably trained personnel and in accordance with the
information given.
4. Normal safety precautions must be taken to avoid the possibility of an accident occurring when operating in conditions of high pressure and/
or temperature.
5. Chemicals must be stored away from heat, protected from temperature extremes and powders kept dry. Normal safe handling procedures
must be used.
6. When disposing of chemicals ensure that no two chemicals are mixed.
Safety advice concerning the use of the equipment described in this manual or any relevant hazard data sheets (where applicable) may be
obtained from the Company address on the back cover, together with servicing and spares information.
CONTENTS
Section
1
Page
INTRODUCTION .............................................................. 2
1.1 General ..................................................................... 2
1.2 The Katharometer ..................................................... 2
1.2.1 Principle of Operation ..................................... 2
1.2.2 Accuracy and Response Time ........................ 3
1.2.3 Zeroing and Calibration .................................. 4
1.3 Katharometer Types .................................................. 6
1.3.1 Basic Construction ......................................... 6
1.3.2 Direct Measurement Types ............................. 6
1.3.3 Differential Measurement Types ...................... 6
1.3.4 Thermally Lagged Types ................................. 6
1.3.5 Thermostatically Controlled Types .................. 6
1.3.6 Intrinsically Safe Katharometers ...................... 7
2
ANCILLARY EQUIPMENT ............................................... 8
2.1 General ..................................................................... 8
2.2 Power Supply Unit .................................................... 8
2.3 Sample Gas Pump .................................................... 8
3
GAS ANALYSIS PANEL ASSEMBLIES ........................... 9
3.1 General ..................................................................... 9
3.2 Assembly 006540 138/TL or 006540 138/TC .......... 9
3.3 Assembly 006540 184/TL or 006540 184/TC .......... 9
3.4 Assembly Fixing Details ............................................. 9
Section
Page
4
INSTALLATION .............................................................. 12
4.1 General ................................................................... 12
4.2 Mounting the Katharometer .................................... 12
4.3 Pipe Connections .................................................... 12
4.4 Electrical Connections ............................................. 13
4.4.1 Non I.S. Systems ......................................... 13
4.4.2 I.S. Systems ................................................. 13
5
MAINTENANCE AND SERVICING ................................ 17
5.1 General ................................................................... 17
5.2 Sources Of Error In Readings .................................. 17
5.2.1 Pressure ....................................................... 17
5.2.2 Flow ............................................................. 17
5.2.3 Leaks ........................................................... 17
5.2.4 Vibration ....................................................... 17
5.2.5 Impurities ..................................................... 17
5.2.6 Sampling ...................................................... 17
5.2.7 Temperature Variations ................................. 17
5.2.8 Bridge Current ............................................. 17
5.3 Zero Adjustment ...................................................... 17
5.4 Sensitivity Adjustment ............................................. 18
5.5 Damaged Or Flooded Katharometer ....................... 18
5.6 Fault Finding ............................................................ 19
6
SPARES ......................................................................... 20
6.1 The Katharometer Unit ............................................ 20
6.2 Drying Absorption Chamber .................................... 20
6.3 Gas Sample Pump .................................................. 20
1
1 INTRODUCTION
1.1
General
1.2
This manual covers the installation and servicing of
katharometer units (thermal conductivity gas analysers) for use
in non-corrosive sample gas applications, together with
essential sampling and ancillary equipment. The manual is
intended to be read in conjunction with appropriate instruction
manuals for:
1) The katharometer power supply unit
2) The read-out device (e.g. potentiometric recorder or
indicator)
3) Any special instructional material appropriate to the gas
analysis panel/assembly as supplied (e.g. soot filter,
dehumidifier, etc.)
Warning. It is essential that all relevant instructions are
carefully studied prior to the installation of katharometer
systems in potentially hazardous areas (specifically those
systems covered by certificates of intrinsic safety). If in any
doubt concerning these systems, please contact the
supplier before proceeding.
The Katharometer
This section describes features common to all katharometer
types, together with the principle of operation upon which the
measurement depends.
1.2.1
Principle of Operation
The katharometer is a nonspecific device which measures gas
concentrations in binary (and some complex) mixtures by
making use of the difference in the thermal conductivity between
the sample and a reference gas. The measurement, being
continuous and automatic, is ideally suited for process
monitoring and control purposes. The universal nature of the
katharometer permits many hundreds of different gas ranges
and mixtures to be measured in a wide variety of applications.
All gases and vapours have a characteristic thermal conductivity
which is largely independent of pressure, and which varies
considerably from one gas to another.
CHLORINE
SULPHUR DIOXIDE
ETHYLENE
HYDROGEN SULPHIDE
CARBON DIOXIDE
NITROUS OXIDE
WATER VAPOUR
ARGON
ETHANE
AMMONIA
CARBON MONOXIDE
NITRIC OXIDE
AIR
NITROGEN
OXYGEN
METHANE
NEON
HELIUM
HYDROGEN
10
20
30
40
50
60 70 80 90 100
200
300
400 500 600 400 800 900 1000
(LOGARITHMIC
SCALE)
Fig 1.1 The Relative Thermal Conductivity of Some Common Gases,
Shown on a Logarithmic Scale, Using Air (=100) as a Base.
2
1
INTRODUCTION…
In a katharometer, this physical property is utilized by passing a carefully controlled direct current through a fine electrical conductor
surrounded by the sample gas. The temperature of the conductor rises, due to the current, until a state of thermal equilibrium is
reached with the surrounding gas. When this condition exists the electrical energy supplied to the conductor is equal to the thermal
energy lost from it by heat transfer through conduction, convection and radiation. Provided that the last two of these losses can be
reduced to a negligible minimum, the temperature of the conductor will depend only upon the heat transfer due to conduction through
the gas. The electrical resistance of a conductor is dependent upon temperature and, by making a measurement of this resistance,
a measurement is also made of the thermal conduction of the gas.
1+
Stabilised
Power
4- Supply
10
R6
Local
Set
Zero
R4
IKΩ
E1
R7 (s)
R1
IKΩ
R3
560
9
560
Span
S2*
Note. A 510Ω resistor is fitted across
terminals 9 and 10 when remote zero is not
fitted.
Rx
S1
*
E2
Optional
Remote Zero
1kΩ
R5
IK
3 Output 1
2 (Single Range)
R8 (y)
5 Output 2
* = Replaced by a resistor on two-filament
katharometers.
6
Direct measurement
(Dual Range)
Differential measurement
S1
S2
S1
S2
E1
E2
E1
E2
= Remote zero operation only.
= Dual range versions only.
Reaction
Values for R7, R8 and Rx depend upon
application.
Fig. 1.2 Katharometer Internal Wiring
The katharometer consists of four (or two) very fine glass coated
platinum wire filaments set in a metal block having a high thermal
capacity. The filaments are connected in a Wheatstone bridge
arrangement (see Fig. 1.2) with one pair of opposite arms sealed
in a reference gas and the remaining pair exposed to the sample
gas. The gas can be pumped through the block or drawn
through by an aspirator (unless supplied under positive pressure
conditions); both methods ensuring a steady sample flow rate.
The Wheatstone bridge is fed from a constant current supply,
and differences in temperature between filament pairs cause an
electrical imbalance in the bridge which is a function of the
difference in thermal conductivity between the gases. The
electrical imbalance of the bridge produces an output signal
which can be indicated directly and calibrated in terms of the
composition of the gas sample. For accurate readings, the
current supply to the Wheatstone bridge must be kept constant;
a change of only 1% in current can cause approximately 3%
change in bridge sensitivity.
1.2.2
Accuracy and Response Time
The accuracy of measurements made using a katharometer
depends largely on the conditions under which it is used. During
initial calibration it is set to better than 1% f.s.d. Factors which
affect the overall accuracy of the measurement when in
operation, are as follows:
1) The accuracy with which reference gases can be made or
analysed for calibration purposes.
2) The accuracy with which the sample gas can be analysed on
site, to provide information for calibration during
manufacture of the katharometer.
3) The presence of impurities in the sample gas, e.g. water
vapour.
4) The introduction into the sample of an additional gas
component not foreseen in the original calibration.
5) Contamination of the sample to be analysed before reaching
the katharometer, e.g. by air leaks in the sampling pipework.
6) Incorrect katharometer supply current.
7) Large deviations of ambient temperature whilst using a
katharometer without temperature compensation.
3
…1
INTRODUCTION
100 %
10% H2 IN AIR
90
80
70
DEAD TIME
% CHANGE
60
50
10%H2 IN AIR
20%CO2 IN AIR
1 Sec
2.5 Sec
90% STEP CHANGE
20 Sec
51 Sec
100% STEP CHANGE
50 Sec
110 Sec
40
30
20
20% CO2 IN AIR
10
0
0
10
20
30
40
50
60
70
80
90
100
110
120
TIME (Secs)
(Both measurements made at 100 ml min–1 flow rate)
Fig. 1.3 Katharometer Unit – Typical Response Curves
Fig. 1.3 shows speed of response curves for two gas mixtures
which may be taken as typical. The curves are seen to be
approximately exponential with an initial delay (the dead time).
Response time depends upon:
a) The geometry of the katharometer cell.
b) The diffusion rate of the gas.
c) The sample flow rate and the length of piping between the
sampling point and the katharometer.
d) The thermal inertia of the katharometer filament.
1.2.3
Zeroing and Calibration
The measurement zero of a katharometer analyser is determined
by the composition of the gas in its reference cells. This is
chosen to have both a thermal conductivity and a temperature
coefficient of thermal conductivity, as close as possible to those
at one extreme concentration of the sample gas, thus ensuring a
symmetrical bridge and reducing zero errors. The gas chosen
must be stable and must maintain these characteristics during
the working life of the katharometer. An analyser zero is usually
one which can be readily checked by reference to a gas which is
easily obtainable in a high state of purity.
The electrical zero of the bridge is set during manufacture, and
an additional trimming adjustment is provided on the unit in the
form of a potentiometer (the ‘zero adjustment’ control) – Figs 1.4
and 1.5. This control may, if required, be remotely installed as
shown in Fig. 1.2. The potentiometer value is chosen to ensure
that serious maladjustment of zero cannot occur.
4
The design of the katharometer is such that its sensitivity
remains constant. Slight contamination of a filament can cause a
change in zero, but the sensitivity will remain constant and the
katharometer may continue to be operated, until it is no longer
possible to compensate for the zero change within the range of
the zero adjustment available.
More severe contamination will require the katharometer to be
cleaned.
1
Thermistor
(Model 006518 Only)
INTRODUCTION…
Insulation Sheet
(Thermal lagging)
Stainless Steel Tubing
Zero Adjustment
12
11
10
9
8
7
6
5
4
3
2
1
Katharometer Block
Sample Inlet
Terminal Connection
Block
Cable Gland
Protection Diodes
(intrinsically Safe Versions
Only)
Sample Outlet
NOTE Ignition arrestors may be fitted to
sample inlet and outlet unions on some
intrinsically safe versions.
Power Transistor
(Model 006518 Only)
Fig. 1.4 Direct Measurement Katharometers: Models 006517 & 006518 (non I.S.) – Models 006539960 & 006548001 (I.S.)
Insulation Sheet
(Thermal lagging)
Thermistor
(Model 006520 Only)
Stainless Steel Tubing
Zero Adjustment
Katharometer Block
Sample Inlet
Power Transistor
(Model 006520 Only)
12
11
10
9
8
7
6
5
4
3
2
1
Terminal Connection
Block
Cable Gland
Protection Diodes
(intrinsically Safe Versions
Only)
Sample Outlet
NOTE Ignition Arrestors may be fitted to
sample inlet and outlet unions on some
intrinsically safe versions.
Fig. 1.5 Differential Measurement Katharometer: Models 006520 & 006521 (non I.S.) – Model 006539970 (I.S.)
5
…1
INTRODUCTION
1.3.2
1.3 Katharometer Types
1.3.1 Basic Construction
Figs 1.4 and 1.5 show the internal layouts of the seven basic
types of ABB katharometer unit, whilst Fig. 4.1 shows
dimensions and fixing details.
The katharometer unit is mounted within a steel case fitted with
fixing straps for wall mounting. Cable glands are provided for
electrical connections, together with sample gas inlet and outlet
connectors appropriate to the type of measurement. The four
platinum filaments comprising the bridge network are mounted
in a plated solid brass block, and stainless steel tubing with
plated brass connectors carry the sample gas to and from this
assembly. The katharometer block is mounted on four thermally
insulating pillars, and the inside faces of the case are lined with
expanded polystyrene to provide thermal lagging. The lid of the
case is similarly insulated, except for the hole protected by a
sliding cover to enable adjustment of the ‘SET ZERO’
potentiometer.
Fitted to the katharometer block is a circuit board on which is
mounted a potentiometer having a slotted spindle aligned with
the hole in the case lid. This is the zero adjustment control.
Clockwise rotation of this control shifts the analyser reading
upscale, anticlockwise down scale.
The basic features described above are common to the four
basic types of katharometer Unit, viz.
–
direct measurement
Thermally lagged
–
differential measurement
–
direct measurement
a) the gas sealed in the reference filaments contains sufficient
water vapour to ensure 100% saturation and the sample gas
is similarly fully saturated, or
b) the sample gas is passed through a desiccating agent such
as calcium chloride before entering the katharometer, or
c) the effect of water vapour is very small compared with the
output from the katharometer bridge, e.g. 0-100% H2 in air –
see Fig. 1.1.
1.3.3
Differential Measurement Types
In a differential measurement katharometer all four filaments in
the katharometer block are exposed to the sample gas, but the
flow of gas is so arranged that, after passing through the first pair
of filaments, it undergoes a chemical reaction before entering
the remaining pair of filaments – see Fig. 1.2. The two sides of
the katharometer bridge thus pass the gas in different
concentrations of the reacting constituent, and the resulting
katharometer reading is a measure of the concentration of this
constituent in the sample gas.
Thermally Lagged Types
Both direct and differential measurement katharometer types
are normally supplied thermally lagged, i.e. the case is lined with
expanded polystyrene to provide thermal insulation and hence
temperature stabilisation for the katharometer block.
differential measurement
In the following sections the features specific to each type are
described in greater detail. Choice of katharometer type is
largely influenced by the application, i.e. the nature of the gas to
be measured, its range, the ambient conditions, and the
sampling arrangements. Although the katharometer principle is
strictly applicable to measurements on binary gas mixtures only
(the ideal being two gases of widely differing thermal
conductivity), its use can be extended by:
a) Exploiting a known relationship between two or more
constituents of a multi-component mixture (e.g. the N2/02
ratio in air) to form a pseudo binary mixture.
b) Sample pretreatment, e.g. drying or saturating with water
vapour.
c) Comparing the sample gas before and after a reaction (a
differential measurement).
6
Direct measurement methods are suitable for dry sample gases
or for wet gases when:
1.3.4
Thermostatically controlled
–
Direct Measurement Types
The direct measurement katharometer is the simplest and most
common type. The sample gas to be measured is delivered to
the exposed filaments, and is compared with a standard gas
sealed in the reference filaments of the katharometer bridge –
see Fig. 1.2.
The katharometer is designed to have a high thermal inertia so
that, during normal operation, no significant temperature
gradient occurs across the block. When exceptional stability is
required, variations in zero due to ambient temperature
fluctuations can become significant. Temperature variations can
also cause errors in sensitivity and hence accuracy. The effect
varies considerably from one gas to another and to offset this the
reference gas is chosen to have a conductivity and temperature
coefficient of conductivity, as close as possible to that of the
sample gas at the zero point.
If it is likely that ambient temperature variations will cause
unacceptable errors, then a thermostatically controlled
katharometer must be used.
1.3.5
Thermostatically Controlled Types
The thermostatically controlled katharometer, in addition to
being thermally insulated, also contains a controlled heating
facility to maintain a stable block temperature of approximately
45°C (or 55°C) ± 0.5°C over an ambient temperature range of
0°C to 40°C (or 0°C to 50°C).
1
1.3.6
INTRODUCTION
Intrinsically Safe Katharometers
When monitoring flammable or potentially flammable gas
mixtures, precautions are necessary to ensure that the
monitoring equipment will not cause an explosion. For this
purpose, an intrinsically safe katharometer and associated
equipment is supplied which limits the amount of electrical
power appearing in the hazardous area to a level insufficient to
ignite the flammable gas, even under a double fault condition.
Intrinsically safe katharometers require a power supply which is
regulated to supply the constant current required, yet with
insufficient energy to cause ignition if a fault condition should
occur. The power supply unit, which must only be of the type
4234 500/501 must be mounted in a safe area and special
limitations are imposed on the parameters of the interconnecting
cables.
The installation of intrinsically safe instrumentation is controlled
by strict regulations and standards. Full details are qiven in the
Operating Instructions for the Intrinsically Safe Power Supply
Unit (Model 4234 500/501). ABB katharometer units for use in
hazardous areas are designed to meet the requirements of ATEX
DIRECTIVE 94/9/EC to code EEx ia IIC T4. These are panel
mounted katharometers and are designated type 006539960/K
or /J for direct and type 006539970/K or /J for differential
measurements. They are covered by EECS certificate No.
BAS01 ATEX 1042. A further certificate of intrinsic safety BAS
No. EX 01E2044, covers the use of katharometer systems
incorporating these units under approved conditions. Particular
care must be taken when installing the equipment and all
conditions specified in the certification schedule must be strictly
complied with. If in any doubt, it is essential to contact the
suppliers before proceeding.
The principle modification to the katharometer unit for
intrinsically safe operation is the addition of a pair of zener
diodes, mounted on a heat sink within the katharometer housing
and connected in parallel across the supply input to the
Wheatstone bridge. The function of these diodes is to limit the
maximum voltage capable of being developed across the bridge
under fault conditions, to a level which provides insufficient
power to cause ignition of a flammable gas sample in contact
with the heated filaments. Sintered metal flame arrestors may be
incorporated into the inlet and outlet unions of the katharometer
as an additional safeguard although these are not required under
the I.S. certification.
Temperature controlled katharometer types cannot be used in
hazardous areas (whether differential or direct measuring), since
the operating currents used to supply temperature control
circuits are potentially hazardous in a flammable environment.
Similarly, and for this reason, furnace elements and most electric
pumps must be excluded from operating in the hazardous area.
7
2 ANCILLARY EQUIPMENT
2.1
General
2.3
Sample Gas Pump
For the katharometer unit to function correctly, the sample gas
must often be suitably conditioned before passing through it.
This section describes various ancillary items which provide
sample conditioning. Each application will include some of these
items connected in the sample line, either mounted together on
a panel with the katharometer, or as separate items piped
together with stainless steel tubing.
In some applications, the sample gas is pumped through the
katharometer unit by a small electric pump, fitted with a filter and
silencer. A diaphragm pump is normally supplied for this purpose
with a motor suitable for a standard single phase a.c. supply.
This pump will aspirate approximately 1 l min–1 of sample gas.
2.2
The pump may be mounted in any position in which the motor
shaft axis is horizontal. Fixing is by four feet having slotted holes
suitable for M4 screws on fixing centres 73 mm x 48 mm. The
pump weighs approximately 2 kg and must be protected by a
1 A fuse in its supply leads.
Power Supply Unit
The katharometer unit is powered from a separately mounted
power supply unit, which is essentially a highly stable constant
current source for the katharometer bridge. The working current
is normally 350 mA. In some applications, however, it is
necessary to operate with the katharometer filaments at a lower
temperature than normal to prevent thermal dissociation of the
sample constituents: a lower working current, usually 250 mA, is
then used. Where sensitivity of certain applications (non I.S.) is
low, the katharometer output can be increased by operating at a
bridge current of 500 mA.
The pump and its filter and silencer are fitted with stems suitable
for connection by means of 6 mm i.d. push-on tubing.
The type of power supply units are as follows:
Model
Function
4234 500/501 Intrinsically safe supply for a
katharometer unit only (230/115 V)
single
4234 600/601 Low energy bridge supply unit for a single
katharometer unit only.
Bridge supply and unstabilised heater supply
for
one
thermostatically
controlled
katharometer unit.
ø8
143
19
Ta A.C. Supply (Single Phase)
Leads 230 long
25
4 Mounting Slots in Feet
6 wide by 10 long
48
73
92
140
All dimensions in mm
Fig. 2.1 Sample Gas Pump (Model 2370 003 – 230 V version or 2370 004 – 115 V version)
8
3 GAS ANALYSIS PANEL ASSEMBLIES
3.1
3.3
General
Most applications for gas analysis will include at least some
items of ancillary equipment, and these items may be
conveniently grouped together on a panel assembly mounted on
a wall adjacent to the sampling point. It is then only necessary to
make the appropriate electrical and piping connections to the
panel.
Assembly 006540 184/TL or 006540 184/TC
Samples which may be measured by this assembly must be
clean, wet or dry, and at a pressure between –l0 in. and +5 in.
water gauge; a direct measurement katharometer is used. This
assembly must not be used for intrinsically safe applications.
Assemblies comprise:
Many different combinations and configurations are possible,
but experience has shown that the majority of applications can
be met from a limited number of basic assemblies, all involving
use of a katharometer unit. A full list of these standard
assemblies, together with dimensional details, may be obtained
from ABB.
Katharometer
The two most commonly occurring assemblies for noncorrosive sample gas measurements are described here.
Assembly
006540 184/TL
006540 184/TC
006517
006518
Flow Gauge
006525 440
006525 440
Needle Valve
006525 480
006525 480
Drying Chamber
006525 600
006525 600
2370 003/004
2370 003/004
Electric Pump
3.2
Assembly 006540 138/TL or 006540 138/TC
The assembly is intended for a clean, wet gas at a pressure
above 5 in. water gauge, and uses a direct measurement
katharometer.
3.4
Assembly Fixing Details
See Table 3.1. Panel assembly drawings for low and high
pressure versions are shown ing Figs 3.1 and 3.2 respectively.
Assemblies comprise:
Assembly
006540 138/TL
006540 138/TC
006517
006518
Flow Gauge
006525 440
006525 440
Needle Valve
006525 480
006525 480
Drying Chamber
006525 600
006525 600
Katharometer
Assembly Number
006540 138/TL & TC 006540 184/TL & TC
006540 203/J & /K
006548 000
All dimensions in mm
Panel dimensions
(horizontal dimensions first)
610 x 305
305 x 610
610 x 305
610 x 305
Fixing centres
(horizontal dimensions first)
572 x 267
267 x 572
572 x 267
572 x 267
Fixing hole diameter (4 holes)
9.5
10.5
10.5
10.5
Projection from wall
152
203
203
203
Inlet pipe fitting for o.d. pipe
diameter
8
8
8
6
Outlet pipe fitting for o.d. pipe
diameter
8
8
8
6
Note:
006540 137/TL as 006540 138/TL but WITHOUT drying chamber.
006540 137/TC as 006540 138/TC but WITHOUT drying chamber.
Table 3.1 Assembly Dimensions
9
…3
GAS ANALYSIS PANEL ASSEMBLIES
Katharometer
unit case
Local zero
adjustment
Gas sample
outlet
Electrical
interconnections
Metering
valve
Flow gauge
Gas
sample
inlet
Drying chamber
Fig. 3.1 006540 203/J & /K and 006540 138 & 137 TL and TC Options Low Pressure Katharometer System
Katharometer
unit case
Local zero
adjustment
Gas sample
outlet
Electrical
interconnections
Metering
valve
Flow gauge
Gas
sample
inlet
Drying chamber
Fig. 3.2 006548 000 High Pressure Katharometer System
10
3
Local zero
adjustment
GAS ANALYSIS PANEL ASSEMBLIES
Katharometer
unit case
Metering
valve
Flow gauge
Drying chamber
L N E
MAINS
Terminal Block
Gas sample inlet
Tee Blocks
Gas sample outlet
Silencer
Filter
Pump
Fig. 3.3 006540 184 TL and TC Versions
11
4 INSTALLATION
4.1
General
This section relates principally to the katharometer unit,
installation details for the ancillary items being given where
necessary under their appropriate heading in Section 2. Where a
katharometer unit is mounted as part of a standard panel
assembly, the following relates to the panel as a whole.
The katharometer unit pipe connections are as shown in
Fig. 4.1. The pipe couplings (two for direct measurement and
four for differential measurement) are suitable for 4 mm o.d.
tubing. Care must be taken in assembling the couplings on to
the tubing to ensure freedom from leaks.
4.3
4.2
Mounting the Katharometer
Fig. 4.1 shows the dimensions and fixing details for the eight
basic types of katharometer unit. The case has overall
dimensions of 233 mm x 157 mm x 109 mm and four fixing
holes are located in straps welded to the back of the case. These
fixing holes are suitable for bolts up to 7 mm diameter, and are
located on centres 178 mm x 178 mm.
Install the katharometer unit with its lid in the vertical plane in a
position which allows adequate access to terminal connections
and controls. The unit can tolerate up to approximately 20° of
inclination from the upright position without adverse effect. The
site must be clean and dry, reasonably well illuminated and free
from extreme levels of vibration. The installation should not be
subject to draughts, heat radiation or strong direct sunlight.
Large fluctuations of ambient temperature must be avoided
unless a thermostatically controlled katharometer is used.
Although the katharometer is robust, care must be taken to
avoid accidental damage during installation (and, in the case of
a panel assembly, to any glass components on the panel).
Keep the distance between the sampling point and the
katharometer as short as possible to minimise time lag due to
long pipe runs. The time lag incurred in such runs can be
significant if, for instance, the katharometer is supplying a signal
to a process control system.
109mm
Pipe Connections
The standard pipe connectors fitted to a panel assembly are
suitable for 8 mm o.d. tubing, (or 6 mm o.d. tubing for
006548 000).
Choice of material for the sample line, and its method of
installation, are important. The following points are given for
guidance.
1) The sample line material must not
a) react chemically with the sample gas.
b) be permeable to the sample constituents or the
surrounding atmosphere.
Most plastics and rubber tubing therefore are unsuitable.
Short lengths of neoprene or nylon tubing may, however, be
used to butt-joint two pipes of material.
2) For dry sample gases the sample line must neither be
permeable to, nor absorb, water vapour.
3) If the sample gas has a dew point above ambient
temperature, the sample line must be installed with a
downward gradient to a water trap fitted at the input to the
katharometer unit. The gradient should be not less than
30 mm per metre. If this is not possible, water traps must be
fitted at each trough.
238mm
21mm
Cable Gland Suitable For Cables
6.5-10.5mm Dia.
80mm
178mm
Fixing Centres
53mm
A
24mm
103mm
178mm
Fixing Centres
162mm
B
152mm
A
22mm
25mm *
25mm
25mm
B
57mm
Four Fixing Holes 7mm Dia
Katharometer Types
Thermally Lagged
Thermostatically Controlled
Intrinsically Safe
(Thermally Lagged Only)
Intrinsically Safe
(High Pressure 10 bar)
Direct
006517
006518
006539 960
J or K
Differential
006521
006520
006539 970
J or K
* This Dimension Increased to 45mm
if flame arrestors fitted.
All Couplings For 4mm o.d. Pipes
Coupling'A' For Direct Measurements Types
Couplings 'A' & 'B' For Differential Measurements Types
006548 001
Fig. 4.1 Katharometer Unit Dimensions and installation Details
12
4
4) When sampling products of combustion, copper tubing
must not be used as it will corrode – the sample gas is often
cooled in passing from a soot filter/sampling point and
considerable condensation can be produced. This
condensation is acidic and must not be allowed to drain into
the katharometer.
INSTALLATION…
2) Where several katharometer with temperature control
circuits are to be installed, a separate Type 4234 600/601
power supply unit must be provided for each katharometer
and connections made in accordance with the handbook for
that unit.
5) The most widely used material is 316 type stainless steel.
Pipes should have an external diameter of 6 mm or 8 mm, as
appropriate, and a wall thickness sufficient to withstand the
maximum pressure encountered at the sampling point.
3) Screened cables should be used to connect the
katharometer to a remote potentiometric indicating device:
these cables should not be installed in the same cable run as
any a.c. supply cables in order to minimise the risk of
interference.
6) If the gas contains solid particles it must be filtered before
entering the sample lines. If there is only a minimal dust
content, a filter can be fitted at the input to the katharometer
unit. Such a filter is often advisable as an extra precaution for
pre-filtered dusty gases.
4) On dual range katharometers, the second signal output is
from terminals 5 and 6; terminals 2 and 5 being common to
both outputs. The range of measurement giving the greater
change in thermal conductivity will always be connected to
terminals 5 and 6. See Figs 1.1 and 1.2 for clarification.
4.4 Electrical Connections – Figs 4.2 to 4.6
4.4.1 Non I.S. Systems
5) When the katharometer is used with an external zero control
instead of the zero adjustment fitted within the unit, connect
the remote zero control (1k0 variable resistor) as shown in
Fig. 1.2, so that clockwise rotation of the spindle produces
an upscale adjustment of the katharometer zero. If the
katharometer has been supplied for remote zero adjustment,
remove the 510 Ω resistor from terminals 9 and 10 and
replace by the remote 1k0 variable resistor before zeroing
the katharometer.
All electrical cables to the katharometer unit must enter via the
20 mm cable glands on the right hand side of the unit casing –
see Fig. 4.1. These glands are suitable for cables 6.5
to 10.5 mm diameter.
Connections must be made to the numbered 12-way screw
terminal block mounted to the right hand side of the circuit board
inside the case.
Remove the case lid after releasing its four fixing screws and
make the connections shown in Fig. 4.2.
When installing cables observe the following:
1) The (loop) lead resistance of the cable from the power supply
unit to the katharometer bridge (i.e. the 350 mA current
supply) must be limited to 4 Ω total per katharometer unless
otherwise stated in the power supply unit instruction manual.
Additional katharometers must be connected in series (Pins
1 and 4) across the power supply unit output terminals.
Further details may be found in the instruction manual for the
power supply unit.
4.4.2
I.S. Systems
For katharometer units which are located in hazardous
environments, special attention must be given to the electrical
connections between the safe and hazardous areas of the
installation. The choice of cable connecting the power supply
unit to the katharometer is strictly limited by the requirement for
a low inductance/resistance ratio. The katharometer bridge
output signal must be connected to indicating devices in the
safe area only via approved zener safety barriers. Full details of
these requirements, together with installation details, are given in
Figs 4.3, 4.4 & 4.5. and the instruction manuals for the particular
system or its associated equipment (Purge Gas Monitor type
6553 and/or power supply unit type 4234 500/501 for example).
Warning. It is essential that these manuals are consulted
before commencing installation.
12
Allocated for special purposes as required
11
10
Provision for external zero control
(1k0 variable resistor) – see also Fig. 1.2
Power supply to temperature control circuit
(Models 006518 & 006520 only)
Bridge output (Range 2)
9
-ve
-ve
6
4
-ve
Power supply (+ve) 350 mA
Note
Terminals 2 and 5 are common.
+ve 5
Power supply (-ve) 350 mA
Bridge output (Range 1)
8
+ve 7
3
+ve 2
1
Fig. 4.2 Katharometer Terminal Block Electrical Connections
13
14
Indicator
e.g. 4689
I2
+
–
+
–
RS2
1
2
3
RS1
1
2
3
3
2
1
3
2
1
3
2
1
RV1
Gas Monitor Type 6553
7.5
99
999
0.02
0.06
0.16
20
60
160
B3
B2
B1
RV2
6
5
4
6
5
4
6
5
4
IIC
IIB
IIA
38
999
999
0.20
0.60
1.60
40
120
320
Note 6
Note 7
Note 8
Note 9
17
18
POWER SUPPLY
TYPE 4234 500/501 +
CERTIFIED [EEx ia] IIC
(–20°C≤Ta ≤+55°C)
CERTIFICATE No
BAS 01 ATEX 7041
POWER SUPPLY
TYPE 4234 500/501
CERTIFIED [EEx ia] IIC
(–20°C≤Ta ≤+55°C)
CERTIFICATE No
BAS 01 ATEX 7041
+
Hazardous Area
CERTIFICATE No
BAS 01 ATEX 1042
Junction boxes (if required) see note 6.
Location: Hazardous or Safe Area
4–
1+
2+ KATHAROMETER
TYPE 0065XXX
CERTIFIED EEx ia IIC T4
10
Tamb=–20°C to +55°C
9
CERTIFICATE No
BAS 01 ATEX 1042
6–
3–
See Notes 2 & 3
Circuit B (see Note 8)
Circuit A
See Notes 2 & 3
2+
3–
4–
KATHAROMETER
1+
TYPE 0065XXX
9
CERTIFIED EEx ia IIC T4
10
Tamb=–20°C to +55°C
Junction boxes (if required) see note 6.
Location: Hazardous or Safe Area
The installation must comply with national requirements (e.g. in the UK EN60079-14:1997).
The system must be marked with a durable label. The label should appear on or adjacent to the principal
item of electrical apparatus in the system or at the interface between the intrinsically safe and nonintrinsically safe circuits.
This marking shall include the word SYST or SYSTEM, e.g.
‘BAS SYSTEM No Ex 01E2044’ or ‘BAS No Ex 01E2044 SYST’
A junction box, if used, must satisfy the requirements of Clauses 6.1 and 6.3.1 of EN50020:1994.
Circuit A or Circuit B may be omitted.
Circuit B may be identical to Circuit A.
This item may or may not be fitted.
The cable may be separate cables or may be installed as separate circuits within a type ‘A’ or a type ‘B’
multicore cable as defined in EN50039(1980) subject to the following:
a. Each circuit shall be individually screened within a type ‘A’ multicore cable.
b. The peak voltage of any other circuit within a type ‘B’ multicore cable must not exceed 60 volts.
See Note 1
20
19
TB6
TB5
See Note 1
Fig. 4.3 System Diagram
Note 2c The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the cables
connected between 4 & 5 of barrier B2 plus terminal 4 of barrier B3 of gas monitor Type 6653 and
terminals 2, 3 & 6 of a katharometer Type 0065XX, must not exceed the following values:
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
Note 2b The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the cables
Note 3
connected between (a) terminals 17 & 18 of the gas monitor Type 6653 and terminals 9 & 10 of a
katharometer Type 0065XX, (b) terminals 19 & 20 of the gas monitor and terminals 9 & 10 of a
katharometer Type 0065XX, (c) terminal 4 & 5 of barrier B1 of gas monitor Type 6653 and terminals 2 &
3 of a katharometer Type 0065XX, must not exceed the following values:
Note 4
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
Note 5
0.40
75
38
IIC
1.20
225
999
IIB
3.20
600
999
IIA
IIC
IIB
IIA
Apparatus which is unspecified except that it must not be supplied from nor contain in normal
or abnormal conditions a source of potential with respect to earth in excess of 250 volts r.m.s
or 250 volts d.c.
Note 2a The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the
cable connected between the + and – terminals of the power supply Type 4234500/501 and
terminals 1 and 4 of a katharometer Type 0065XX must not exceed the following values:
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
Note 1
GAS MONITOR
TYPE 6553
CERTIFIED [EEx ia] IIC
Tamb=–20°C to +40°C
CERT No BAS 01 ATEX 7043
Indicator
e.g. 4689
I1
See Note 9
Safe Area
…4
INSTALLATION
6
5
4
Apparatus which is unspecified except that it must not be supplied from nor contain in
normal or abnormal conditions a source of potential with respect to earth in excess of 250
volts r.m.s or 250 volts d.c.
Zener Diode Safety Barrier
MTL 7055ac
CERTIFICATE No
BAS 99 ATEX 7285
3
2
1
See Note 1
7.5
99
999
0.02
0.06
0.16
20
60
160
IIC
IIB
IIA
0.40
1.20
3.20
75
225
600
The system must be marked with a durable label. The label
should appear on or adjacent to the principal item of electrical
apparatus in the system or at the interface between the
intrinsically safe and non-intrinsically safe circuits.
This marking shall include the word SYST or SYSTEM, e.g.
‘BAS SYSTEM No Ex 01E2044’ or ‘BAS No Ex 01E2044
SYST’
Note 5
A junction box, if used, must satisfy the requirements of
Clauses 6.1 and 6.3.1 of EN50020:1994.
The installation must comply with national requirements (e.g.
in the UK EN60079-14:1997).
Note 4
Note 6
The cable may be separate cables or may be installed as
separate circuits within a type ‘A’ or a type ‘B’ multicore cable
as defined in EN50039(1980) subject to the following:
a. Each circuit shall be individually screened within a type
‘A’ multicore cable.
b. The peak voltage of any other circuit within a type ‘B’
multicore cable must not exceed 60 volts.
Junction boxes (if required) see note 6.
Location: Hazardous or Safe Area
Fig. 4.4 PSU in Association with a Katharometer and Other Safe Area Apparatus with One Zener Diode Barrier
38
999
999
Note 2b The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the cable
connected between 4 & 5 of an MTL 7055ac zener diode safety barrier and terminals 2 & 3 of a
katharometer Type 0065XX, must not exceed the following values:
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
IIC
IIB
IIA
CERTIFICATE No
BAS 01 ATEX 1042
See Notes 2 & 3
2+
3–
4–
KATHAROMETER
1+
TYPE 0065XX
9
CERTIFIED EEx ia IIC T4
10
Tamb=–20°C to +55°C
Hazardous Area
Note 3
POWER SUPPLY
TYPE 4234500/501
CERTIFIED [EEx ia] IIC
(–20°C≤Ta≤+55°C)
CERTIFICATE No
BAS 01 ATEX 7041
+
Note 2a The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the cable
connected between the + and – terminals of the power supply Type 4234500/501 and terminals 1
and 4 of a katharometer Type 0065XX must not exceed the following values:
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
Note 1
Safe Area
Apparatus
(see Note 1)
Safe Area
4
INSTALLATION…
15
16
B2
3
2
1
6
5
4
6
5
4
Zener Diode Safety Barriers
MTL 7055ac
CERTIFICATE No
BAS 99 ATEX 7285
B1
3
2
1
See Note 1
7.5
99
999
0.02
0.06
0.16
20
60
160
IIC
IIB
IIA
38
999
999
40
120
320
The system must be marked with a durable label. The label should
appear on or adjacent to the principal item of electrical apparatus in
the system or at the interface between the intrinsically safe and nonintrinsically safe circuits.
This marking shall include the word SYST or SYSTEM, e.g.
‘BAS SYSTEM No Ex 01E2044’ or ‘BAS No Ex 01E2044 SYST’
Note 5
A junction box, if used, must satisfy the requirements of Clauses 6.1
and 6.3.1 of EN50020:1994.
The installation must comply with national requirements (e.g. in the
UK EN60079-14:1997).
Note 4
Note 6
The cable may be separate cables or may be installed as separate
circuits within a type ‘A’ or a type ‘B’ multicore cable as defined in
EN50039(1980) subject to the following:
a. Each circuit shall be individually screened within a type ‘A’
multicore cable.
b. The peak voltage of any other circuit within a type ‘B’ multicore
cable must not exceed 60 volts.
Junction boxes (if required) see note 6.
Location: Hazardous or Safe Area
Fig. 4.5 PSU in Association with a Katharometer and Other Safe Area Apparatus withTwo Zener Diode Barriers
0.20
0.60
1.60
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
BAS 01 ATEX 1042
See Notes 2 & 3
2+
4–
KATHAROMETER
1+
TYPE 0065XX
CERTIFIED EEx ia IIC T4
6–
Tamb=–20°C to +55°C
3 – CERTIFICATE No
Hazardous Area
Note 3
POWER SUPPLY
TYPE 4234500/501
CERTIFIED [EEx ia] IIC
(–20°C≤Ta≤+55°C)
CERTIFICATE No
BAS 01 ATEX 7041
+
Note 2b The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the
cable connected between 4 & 5 of an MTL 7055ac zener diode safety barrier plus terminals
4 of a second MTL 7055ac zener diode safety barrier and terminals 2, 3 & 6 of a katharometer
Type 0065XX, must not exceed the following values:
IIC
IIB
IIA
Apparatus which is unspecified except that it must not be supplied from nor contain in
normal or abnormal conditions a source of potential with respect to earth in excess of 250
volts r.m.s or 250 volts d.c.
Note 2a The capacitance and either the inductance or the inductance to resistance (L/R) ratio of the
cable connected between the + and – terminals of the power supply Type 4234500/501 and
terminals 1 and 4 of a katharometer Type 0065XX must not exceed the following values:
Group Capacitance Inductance or L/R ratio
in µH/Ohm
in mH
in µF
Note 1
Safe Area
Apparatus
(see Note 1)
Safe Area
…4
INSTALLATION
5 MAINTENANCE AND SERVICING
5.1
General
The katharometer unit and its associated equipment are
designed for stable and accurate operation over long periods. It
is not normally necessary to check the accuracy of the system
more than once a month, and in most cases experience will
show that this period may be extended.
Apparently false or unstable readings may occur due to faults in
the installation of the measuring system. These possible sources
of error are summarised below.
5.2 Sources Of Error In Readings
5.2.1 Pressure
Thermal conductivity does not vary significantly over a very wide
range of pressure but large deviations from atmospheric
pressure can be significant. Gases containing large molecules
(such as carbon dioxide) are the most sensitive to pressure
changes. High pressure samples should be passed through a
reducing valve and analysed at atmospheric pressure.
5.2.2
Flow
The katharometer zero balance and sensitivity are independent
of the sample flow rate, since gas enters the katharometer cells
by molecular diffusion. Speed of response of the analyser is,
however, affected by the flow rate. It is advisable to limit the rate
to below 500 mI min–1, the usual setting being about
150 mI min–1. In installations where an absorption or drying
chamber is fitted, a compromise has to be made to avoid too
rapid consumption of the absorbing or drying material without
excessive loss of response speed. For most applications, it is
recommended that the flow be greater than 50 mI min–1. Care is
necessary in the design of sample pipes for very low flow rates:
if the flow is less than 50 mI min–1, precautions must be taken to
avoid gases absorbing and/or desorbing from the surface of the
pipeline, or pipeline permeability effects.
5.2.3
Leaks
Leaks in the pipework installation must be avoided especially
when the gas sample is below atmospheric pressure. On a
katharometer with reference air zero, a leak will have little effect
at zero, but will become more noticeable on upscale readings.
The total effect will be an apparent loss in instrument sensitivity.
A leak can often cause spurious instability which is not due to a
fault in the katharometer.
5.2.4
Vibration
Vibration does not normally affect a katharometer, but if
pulsation of the sample flow produces a resonance in the
katharometer cells, errors can arise due to cooling of the
filament.
5.2.5
Impurities
The most likely source of error in an otherwise correctly
operating system is the presence of an impurity in the sample,
i.e. the katharometer has been calibrated without knowledge of
this impurity. The impurity could arise from the use of rubber or
plastic sample tubes, for example, which can cause
contamination from the surface of the tube. For this reason,
stainless steel tubing is recommended. A further possibility is the
unexpected presence of water vapour in a supposedly dry
sample gas or, conversely, lack of saturation in a wet gas.
Errors may also be introduced due to deposition on the
filaments, indicating that the sample has not been adequately
filtered before entering the katharometer. Such contamination
can be compensated for by adjustment of the zero control, and
will not produce serious errors until the range of zero adjustment
has been exhausted.
5.2.6
Sampling
Errors due to faulty sampling can result in false indications of the
true conditions. This is particularly important where the
katharometer forms part of a process control loop.
When wet gases are being sampled, it is important to ensure
that there are no points in the system where condensate can
become trapped causing blockage. It is recommended that
stainless steel sample tubing is used wherever possible, and
that the katharometer be installed as close to the sampling point
as is practicable.
5.2.7
Temperature Variations
The katharometer zero balance is not substantially affected by
typical variations in ambient temperature, since the
katharometer is both electrically and thermally symmetrical
when the same gas surrounds the four filaments. Variations in
Sensitivity due to temperature changes can, however, occur.
These can reduce accuracy particularly on sensitive ranges. The
greater the difference in conductivity temperature coefficients of
the sample constituents, the greater will be any sensitivity error
caused by a temperature change. To overcome such problems
a thermostatically controlled katharometer is recommended
(Models 6518 or 6520).
The temperature of a gas at the sampling point has ‘little effect
on the measurement unless it is unduly high and the sampling
tube is very short; in any case the errors are small. If necessary,
the sample pipe should be extended to 1 or 2 metres to allow the
gas to cool.
5.2.8
Bridge Current
The katharometer bridge working current is normally 350 mA
and is supplied by a stabilised power supply unit. It is essential
that the working current remains stable during operation, since
the output of the katharometer is approximately proportional to
the cube of the bridge current.
5.3
Zero Adjustment
The zero balance of the katharometer is set during manufacture.
At periodic intervals this zero balance should be checked. A
change in zero has the effect of displacing all parts of the scale
by an equal amount, and can thus be corrected by setting the
indicated reading to any known concentration being sampled.
Whenever necessary the katharometer must be calibrated
against a pure gas or a readily available reference gas.
Alternatively, the reading may be set against an accurate
chemical analysis of the gas. To adjust the zero, first set the zero
of the indicating device and then, with the zero (reference) gas
passing through the katharometer, adjust the zero control on the
katharometer unit (it is not necessary to remove the cover to do
this) until the desired value is indicated; a clockwise rotation
produces an upscale change in reading.
17
…5
MAINTENANCE AND SERVICING
5.4
Sensitivity Adjustment
The sensitivity of a katharometer unit is stable and no attempt
must be made to adjust this. The multiturn potentiometer, R7,
(typically 500 ohms or 200 ohms – see Fig. 1.2) is sealed
following adjustment at the factory. On two range versions, an
additional potentiometer for the second range is also preset and
sealed as appropriate. No responsibility will be accepted by ABB
for the performance of any katharometer on which the
potentiometer seals have been broken.
5.5
Damaged Or Flooded Katharometer
If the indicated reading from a katharometer moves suddenly
hard up or down scale when the unit is sampling a gas known to
be within its measurement range, the cause may be a broken
katharometer filament or the katharometer cells becoming
flooded with water – see Section 5. A rapid way to determine this
is to measure the voltage across the katharometer bridge. If the
voltage across terminals 1 and 4 on the katharometer unit is
more than 4 V with 350 mA passing, one filament could be
broken: two filaments broken cause a reading permanently at
one end of the scale with no response to the zero adjustment. A
filament which is damaged but not broken will give erroneous
readings which vary when the instrument is tapped lightly.
Caution. Do not insert any type of probe into the gas
sample pipes on the katharometer units, and especially not
the filament cells. In cases of difficulty contact the
manufacturers, quoting the instrument number and giving
full particulars of the problem.
If the katharometer unit is accidentally flooded with water, or
condensed water vapour accumulates inside the katharometer
block due to inadequate filtering, the indicated reading will move
hard up or down scale and the voltage measured across
terminals 1 and 4 will be less than 2.8 V with 350 mA bridge
current passing. Water is difficult to remove from a katharometer,
but may be attempted as follows:
1) Disconnect the katharometer unit completely from its
housing.
2) Turn the unit upside down and raise the inlet so that the block
is at an angle of 45° – drain of any excess liquid.
3) Pour a little rectified spirit, ethyl alcohol or methylated spirits
through the katharometer. Allow as much liquid as possible
to drain out – gentle shaking will assist.
4) Repeat step 3) several times.
5) Replace the katharometer unit and if this is a thermostatically
controlled type (Model 6518) connect the heater supply
(terminals 7 and 8) and the bridge supply (terminals 1 and 4).
If the katharometer is a thermally lagged type, connect the
bridge supply (terminals 1 and 4) only.
6) Pass dry air or other readily available dry gas through the
katharometer. It is possible for the instrument to take a day or
more to dry out completely: the zero may also drift for several
days.
18
Caution. If the fault is traced to a broken or damaged
filament, the complete unit must be returned to the factory
for repair or replacement. Do not attempt to repair or
replace a katharometer cell.
5
5.6
MAINTENANCE AND SERVICING…
Fault Finding
The following is a list of faults which may occur on a katharometer installation, together with their possible causes and remedies:
Fault
Possible Cause
Low reading Incorrect zero
All pipe connections.
Low output from power supply unit
See power supply unit instruction manual.
Desiccant exhausted
Replace desiccant.
Gas absorbent exhausted
Replace absorbent.
Presence of unexpected interfering gas or incorrect
sample conditions notified to factory at time of
calibration
Remove interfering gas or consult ABB. Check data sent
with order and consult ABB.
Temperature control not working (Models 006518 or
006520 only)
Too hot. Check power transistor or for open circuit
thermistor.
Mechanical zero of indicator/ recorder.
Zero of katharometer.
High output from power supply unit
See power supply unit instruction manual.
Desiccant exhausted
Replace desiccant.
Presence of unexpected interfering gas or incorrect
sample conditions notified to factory at time of
calibration
Remove interfering gas or consult ABB.
Check data sent with order and consult ABB.
Temperature control not working (Models 006518 and
006520 only)
Too cold. Check power supply wiring or for short circuit
transistor or thermistor.
Reading at
Faulty indicator/recorder
or near zero
No output from power supply unit
Reading
hard
downscale
Mechanical zero of indicator/recorder.
Zero of katharometer.
Air leak in pipeline
High reading Incorrect zero
Reading
hard
upscale
Check or Test
Is the indicator/recorder power supply on?
See power supply unit instruction manual. Open circuit in
wiring connections.
Drawing in atmospheric air
Check piping for leaks.
Sample concentration outside measurement range of
katharometer
Check by independent analysis.
Broken filament(s)
If voltage across terminals 2 and 4 is more than 4 volts,
return katharometer for repair.
Sample concentration outside measurement range of
katharometer
Check by independent analysis.
Connections to indicator/recorder/power supply unit
reversed
Check wiring to indicator/recorder/power supply unit.
Broken filament(s)
If voltage across terminals 1 and 4 is more than 4 volts,
return katharometer for repair.
Katharometer flooded with water
If voltage across terminals 1 and 4 is less than 2.8 volts,
dry out or return katharometer for repair.
External zero control not connected when required.
Check if katharometer has been supplied for remote zero
adjustment (see also Fig. 1.2).
19
…5
MAINTENANCE AND SERVICING
Fault
Possible Cause
Check or Test
Erratic
readings
Unsteady output from power supply unit
Wiring connections between katharometer and
indicator/recorder/power supply unit.
See power supply unit instruction manual.
Check wiring connections.
Damaged (but not broken) filament
Tap the block lightly to check if reading changes; if so,
return katharometer for repair.
Interference pickup in wiring
Disconnect indicator leads to establish whether
interference originates from the katharometer or from
pickup in wiring leads. If the latter, use screened cables.
Air leaks
Check piping for leaks.
Temperature control circuit not functioning correctly
(Models 006518 and 006520 only)
Connections to power supply unit. Fault in temperature
control circuit - check especially thermistor and power
transistor.
Observe flow gauge reading (if fitted)
Erratic sample flow
Irregular water flow in aspirator (if fitted)
Check water supply to aspirator.
Slow
Pipeline partially blocked, e.g. at a condensate trap
response to
changes in
Water flow aspirator incorrect (if fitted)
sample
conentration
Check piping.
Readings
sensitive to
changes in
flow
Check for leaks. Replace all rubber or plastic pipes with
stainless steel.
Is water flowing from the aspirator tailpipe?
Is there a regular continuous flow of bubbles in the glass
chamber? Adjust water supply as necessary.
The katharometer is not sensitive to changes in flow
rate. The cause could be air leaks, ingress of water
vapour or retention of gas on walls of sample pipe
6 SPARES
The following is a list of spare parts for the principle items used on typical katharometer assemblies. Enquiries and orders for spares
should be addressed to ABB.
6.1
The Katharometer Unit
Item
006517000
006518000
006539960/J 006539960/K
006548001
Bulkhead coupling kit for 4 mm o.d. pipe
006525135
006548008
Connecting pipe (katharometer block to bulkhead
coupling)
006517180
006517180
6.2
Drying Absorption Chamber
Item
6.3
Part Number
006525 600
006548 003
Acrylic chamber (140 ml)
006525710
006525720
Refurbishment kit (including
seals and gauze)
006525605
006548007
20
Gas Sample Pump
Item
Part Number
Sample pump 230 V 50/60 Hz
002370003
Sample pump 115 V 50/60 Hz
002370004
Valve, spring and diaphragm kit
006540125
PRODUCTS & CUSTOMER SUPPORT
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We provide a comprehensive after sales service via a Worldwide
Service Organization. Contact one of the following offices for
details on your nearest Service and Repair Centre.
United Kingdom
ABB Limited
Tel: +44 (0)1453 826661
Fax: +44 (0)1453 829671
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dissolved oxygen and hydrazine analyzers.
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purge-gas monitors, thermal conductivity.
Client Warranty
Prior to installation, the equipment referred to in this manual must
be stored in a clean, dry environment, in accordance with the
Company's published specification.
Periodic checks must be made on the equipment's condition. In
the event of a failure under warranty, the following documentation
must be provided as substantiation:
1. A listing evidencing process operation and alarm logs at time of
failure.
2. Copies of all storage, installation, operating and maintenance
records relating to the alleged faulty unit.
ABB has Sales & Customer Support
expertise in over 100 countries worldwide
The Company’s policy is one of continuous product
improvement and the right is reserved to modify the
information contained herein without notice.
Printed in UK (06.04)
www.abb.com
IM/6517–6518
Issue 5
© ABB 2004
ABB Limited
Oldends Lane, Stonehouse
Gloucestershire, GL10 3TA
UK
Tel: +44 (0)1453 826661
Fax: +44 (0)1453 829671
ABB Inc.
Analytical Instruments
9716 S. Virginia St., Ste. E
Reno, Nevada 89521
USA
Tel: +1 775 850 4800
Fax: +1 775 850 4808