Working Pressure
Due to our advanced manufacturing methods we are able to provide the following key advantages:
- Elfab manufactures all its products to a zero manufacturing design range (MDR). This service is provided at no additional charge.
- Elfab offers a better than industry standard performance tolerance of 3% rather than 5%.
How does this help me as a user? You can work the process to a higher pressure using the same set pressure for the rupture disc, giving shorter process times and tighter safety margins or you can possibly rationalise your stock holding inventory.
Example: This is best explained as follows, based on ordering a 100 psig rupture disc. The following are typical parameters of what is then supplied.
| 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 |
- 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 = 100 psig +/- 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
- 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.
- 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.
- Operating Ratio: This is the maximum recommended pressure that the rupture disc should be subjected to in service. Above this figure the rupture disc will fatigue and give a reduced service life. It is stated as a percentage of the Marked Burst.
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