Using ordinary valves in vacuum

[knowlittle]

I have a low pressure gas setup (typically operates 10-20 psi). Prior to operation, I need to evacuate the setup with a vacuum pump. The setup has various 2- and 3-way valves and stainless steel tubings. My question is if ordinary gas valves and vacuum are compatible. Since the valves are designed not to leak in pressure, I wonder if they may leak in vacuum. Thanks.

I have used vacuum valves before. They were sealed with corrugated baffle and quite bulky. The valves currently in my setup are 1/10 of the size.

 

[IRstuff]

Kind of depends on how much leakage you can tolerate, doesn't it?

TTFN
faq731-376

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[knowlittle]

How much leak can I tolerate?
The pump is turbomolecular type and is capable of 10e-8 torr. I am getting 10e-6. The setup is for the analysis of impurity gases with 0.1 to 1 ppm accuracy. Basically, if there is a room for improvement, I will take your suggestion. Thanks.

 

[EdStainless]

You might find some dual seal valves that are better without going to metal bellows.
But positive pressure service valves will never make 10e-8.
I have tried.

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