| |
Elfab |
Zero MDR3 |
5% MDR |
10% MDR |
| Lowest Possible
Marked burst pressure psig1 |
100 |
100 |
95 |
90 |
| Burst Pressure
tolerance +/-2 |
3% |
5% |
5% |
5% |
| Minimum Burst
Pressure psig |
97 |
95 |
90 |
85 |
| Operating Ratio
%4 |
92 |
90 |
90 |
90 |
| Maximum Working
Pressure psig |
92 |
90 |
85.5 |
81 |
1
Marked Burst: This is stated in
one of two ways: With Zero Manufacturing Design Range, where
the Marked Burst is the same as the Ordered burst. Or with
10% Manufacturing Design Range, the Marked Burst is the
mean of the actual test bursts which must lie between this
limit. Eg:
- Burst pressure ordered = 100 psig +/- 5% @ 68’F.
With Zero M.D.R.
Marked Burst on disc tag = 100psig +/- 5%@ 68’F.
- Burst pressure ordered = 100 psig +/-5%@ 68’F.
With 10% M.D.R.
Actual Test Burst mean = 90 psig. Marked Burst = 90 psig
+/- 5%@ 68’F
2
Burst Pressure Tolerance: This is the limit
of the burst pressure of the disc, normally stated as a plus
or minus percentage. Refer to ASME VIII Division 1 Section
UG127.
3
Manufacturing Design Range: This is the range,
normally expressed as Zero, Minus 5 % or minus 10%, applied
to the requested Burst Pressure. The mean of the test bursts
carried out must lie within this range.
4
Operating Ratio: This is the maximum recommended
pressure that the disc should be subjected to in service.
Above this figure the disc will fatigue and give a reduced
service life. It is stated as a percentage of the Marked Burst.
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