Is a check valve installed on the compressor anti-surge line?
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At the workplace, I identified a problem by checking the PID diagram: the anti-surge line at the compressor outlet was set in front of the check valve, and I couldn’t understand why it was arranged that way. I think: the check valve is used to prevent gas from flowing back from the compressor’s outlet, but since the anti-surge device in the PID diagram is located before the check valve, won’t the gas in the anti-surge pipeline flow back?
There is a post on the forum; please check http://bbs.hcbbs.com/thread-1193794-1-1.html
I don’t think there’s any problem; we both have it
This post was last edited by shijiazhuang on 2017-5-24 at 22:00. Placing it in front is the correct approach; thanks to the function of the check valve and its distance from the compressor outlet, pressure can be released quickly to prevent surging. If it is placed behind, this won’t be possible in systems of sufficient size, and if there are other materials present, it’s hard to imagine what consequences pressure release could have. As for the backflow you mentioned, it’s impossible to occur – the outlet of all surge valves should be at atmospheric pressure, whether they are used for venting to the outside or for sealed discharge
Anti-surge is about from outlet to inlet – how can there be backflow?
Placing it in front of the check valve is the correct approach; it reduces the volume available for pressure release, and moreover prevents surging from occurring in the event that the check valve gets stuck.
In the projects I am aware of, there are two scenarios: 1) check valves are installed both before and after the anti-surge line; 2) an anti-surge valve is installed only after the anti-surge line.