I need to devise a way to ensure only NG passes through a pipe, and no condensates or other liquids. It is ok to shut down the pipeline if liquids would be detected. The dimensions involved are small and space limited.

Is there a valve which shuts if liquid starts passing through but stays open for gas? Aside from a involved solution with a trap with a sensor attached, is there any other way to solve this?

  • $\begingroup$ A ball valve? The ball floats on the liquid and closes the valve if the level is too high... $\endgroup$
    – Solar Mike
    Commented Nov 4, 2019 at 14:54
  • $\begingroup$ Have you looked into if there is a material that is highly selective for NG that can be made into a cartridge filter? Maybe start with a vendor like Parker? $\endgroup$
    – J. Ari
    Commented Nov 4, 2019 at 15:13
  • $\begingroup$ Thanks for the ideas! The ball valve seems workable as a concept I'll have a look if I can find a ready product. I'll also give Parker a call and see if they have smth on the shelf. $\endgroup$
    – Romeoman
    Commented Nov 4, 2019 at 15:53

1 Answer 1


What are you searching for is called:

Thermostatic expansion valve or (TXV).

You have one of those in your air conditioner. Because the compressor of AC's are designed to handel only vapour.

  • $\begingroup$ Thank you, this is very close. I'd need a TXV tuned for NG phase diagram but now I have a working principle! $\endgroup$
    – Romeoman
    Commented Nov 6, 2019 at 13:46

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