USA What is an “Operating Ratio”? Ratio ?

May 29, 2000
USA
...rupture disks and related products
Operating Ratio
WEBSITE: http://www.zook.cc
What is an “Operating
Ratio ?
Ratio”?
ZOOK Rupture Disk Seminar
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May 29, 2000
Operating Ratio
All styles of rupture disks have an
operating ratio.
Based on a disks design, it will only
withstand so much pressure before there
is an effect on the disks main priority
p
y - to
burst at the stamped rating.
Operating above this pressure may
shorten the disks life expectancy and may
cause nuisance bursts.
Disk Design Classifications
and Operating Ratios
All Graphite
URA/SRA/SB
SFAZ
Operating
Ratio
90%
90%
85%
Fragmenting
Non-Fragmenting
Non-Fragmenting
g
g
D/ProPos/ProVac
PB
ARD
80%
70%
50%
Minimal Fragmenting
Fragmenting
Minimal Fragmenting
Series
ZOOK Rupture Disk Seminar
Classification
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May 29, 2000
Example:
The URA disk design has a 90% operation ratio.
ratio
This means that you can safely operate up to
90% of the disks marked burst pressure before
having an effect on the disks performance.
If the disk has a –10% MDR and the specified
burst rating is 100.00 psig, the disk will be
marked between 90.00 and 100.00 psig.
Therefore the max recommended operating
pressure is 81.00 psig.
OPERATING RATIO
SPECIFIED
BURST RATING
MAWP
100
95
-10%
MDR
LOW SIDE
OF MDR
90
85
90%
OPERATING
RATIO
80
75
ZOOK Rupture Disk Seminar
81 PSI MAX
SAFE OPERATING
PRESSURE
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May 29, 2000
Click mouse or press enter to start animation.
To replay click on “REPLAY” when slide is complete.
To continue click on “CONTINUE”.
Calculating the Operating Ratio
SPECIFIED
BURST RATING
MAWP
100
Rupture
disk will be
marked
somewhere
within this
range
95
-10%
MDR
Customer Specifies MAWP
of 100.00 psig
Customer Requests
MDR of –10%
90
85
Calculate the Max safe operating
90%
pressure based on lowest possible
OPERATING
marked burst rating
RATIO
LOW SIDE
OF MDR
85 PSI
OPERATING
PRESSURE
81.00 PSIG
80
Customer
Specifies
85.00 psig
Disk (as specified)
will not
perform
Process operating pressure
to customers specifications
REPLAY
CONTINUE
ZOOK Rupture Disk Seminar
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May 29, 2000
Re-Calculating the Operating Ratio
Rupture
disk will be
marked
somewhere
within this
range
SPECIFIED
BURST RATING
MAWP
100
-5%
MDR
LOW SIDE
OF MDR
95
Adjust MDR to –5%
5%
90
90%
Calculate the Max safe operating
OPERATING
pressure based on lowest possible
RATIO
marked burst rating
85.50 PSIG
85 PSI
OPERATING
PRESSURE
85
80
Disk will now perform to
customers specifications
75
Safe Operating Range - SOR



Based on the disk type or options ordered
ordered, the low
end performance will be determined (usually either
full vacuum or -0-).
Calculate the “Maximum” safe operating pressure
(specified burst pressure – low end MFG Range –
disk operating ratio)
ratio).
These two figures are combined to supply a range
of pressures that the disk will safely perform within,
or the "safe operating range".
ZOOK Rupture Disk Seminar
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May 29, 2000
Example
D-V
D
V series disk rated 100.00
100 00 psig with standard MFG range
of -5/+9 psi.
Determine the low end of range:
 Because disk style has a vacuum support, the low end
of SOR = full vacuum.
Calculate the high end of range:
 100.00 psi – 5.00 psi = 95.00 psi
 “D” series disk has an 80% operating ratio.
 95.00 psi – 20% = 76.00 psi
Combine the two for full range:
Safe Operating Range: full vacuum to 76.00 psi
Available tools



ZOOK Rupture Disk Seminar
Specification forms (available from
ZOOK). Forms act as an excellent guide
to gathering required information
OR
ZOOK website – great for interactive
phone discussions
discussions.
OR
Send us design spec sheets – we will do
the rest!
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May 29, 2000
Additional Information:
For additional information on ZOOK
rupture disks and products, please visit
us by any of the following methods:
 On the web at www.zook.cc
543 1043
 T
Tollll ffree USA att 800
800-543-1043
 Local at 440-543-1010
 By fax at 440-543-4930
ZOOK Rupture Disk Seminar
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