helium leak rate based on 5% helium fill
helium leak rate based on 5% helium fill
(OP)
I'm trying to develop a Mass spec leak rate for a high pressure valve. (3000-3200 psig)
We are allowed a mass loss rate of 0.0015 grams/hr. (nitrogen)
I would like to convert that to scc/sec nitrogen
and then to scc/sec Helium leak rates.
Once that is accomplished I need to develope a relative Helium leak rate when the system uses a 5%He and 95%N2 mix.
I have been given values internally but would like to independently confirm these numbers. ( or come reasonably close)
We are allowed a mass loss rate of 0.0015 grams/hr. (nitrogen)
I would like to convert that to scc/sec nitrogen
and then to scc/sec Helium leak rates.
Once that is accomplished I need to develope a relative Helium leak rate when the system uses a 5%He and 95%N2 mix.
I have been given values internally but would like to independently confirm these numbers. ( or come reasonably close)





RE: helium leak rate based on 5% helium fill
RE: helium leak rate based on 5% helium fill
I feel more confident now to review these figures with the current source who calculated the leak rate to 9.96e-6. I don't want to build this test any tighter than we need. The safety factor is built into the original mass loss rate and we need not compound it.
Thanks
gary
RE: helium leak rate based on 5% helium fill
RE: helium leak rate based on 5% helium fill
falcon4,
may ask which method/technique will you use to detect helium leakage from your high pressure valve?
Thanks and Regards, 'NGL
RE: helium leak rate based on 5% helium fill
Once pressure and temp stabilize we'll do a 60 second pressure decay to check for gross leakage. Once acceptable we'll close the chamber and start pump down and subsequent leak test.
Do you have other suggestions?
Gary
RE: helium leak rate based on 5% helium fill
as far as I can understand, you do not use a sniffer probe (local, semi-quantitative method), but you build a vacuum chamber around the valve under test (global, quantitative method).
Am I right?
Thanks, 'NGL
RE: helium leak rate based on 5% helium fill
Since the leak rate is for the cummulative rates of all possible leak paths, we are interested in the "global" as you put it, value. If we find a non-conforming valve, we can either "probe" it, use leak detection fluid, or immerse it in alcohol or DI water, to locate the leak points.
Gary