Test medium for Gas PSV`s. N2 or Air?

[Dalis]

Hi there

I have a question about testing of PSV`s

Right now, we use N2 as test medium on the test stand. But we are about to rebuild it, and use compressed air (Not O2!) due to the location of the test stand and dangers of suffication.
I`ve heared some engineer`s concerned about the explotion hazzard if we use air instead of N2.

Is this an issue, or maybe he`s thinking of compressed oxygen?

Currently we are limited to 60 Barg when testing on gas. If we are testing any gas valves above 60 Barg, we have to use hydro testing.

Acording to API 527 and API 576, its stated we shold use Air or N2.


So my question is, have anyone ever heard of any accidents related to the use of comressed air?

 

[Ripz]

Compressed air is not explosive.

His concern may be a breach of containment because of the pressure used. (As is the concern for any pressure test)

The use of any gas, (air or N2) will have almost the same compressed energy when pressurised and poses the same risks, in that regard.

Proper inspection of your equipment and safe testing practices mitigates against accidents.

 

[Duwe6]

Air is a little over 70% nitrogen and only 20.9% oxygen. At high pressures and partial-pressures of O2, solvents, especially grease may spontaniously combust. Don't know what that 'high pressure' is, though. I do know that most folks do not take "oxygen clean" precautions on 3000 psi compressed air. Thus there isn't really any good engineering reason to stop at 60barg/870psi. And you cannot swap compressible gas and incompressible water. If your PRV is "SCFM"