Helium permeability in Fluorocarbon O-rings

Posted by Neil Cookson on November 5, 2004 at 15:27:00:

I am tring to assess the permeability of helium gas through Flurocarbon O-rings (James Walker FR58/90)as we are conducting a high pressure leakage test in our ball valves for the Offshore industry.

The test is carried out at ambient temperature introducing a 90% Nitrogen/ 10% Helium gas mix at around 310 bar into the body of the valve. There is an acceptable leakage rate for Helium which we then use to estimate the actual leakage of methane on site.

For us to assess whether the test will be worth doing we need to understand what amount of helium that will permeate through the O-rings.

Hope someone can help.

Neil