3 replies to this topic

[kholish2000]

Hi everybody,
When the pressure of the air instrument system is achieved the setting target (i.e 7 bar), unloader valve will work. the result is dischard flow is much lower than minimum flow design. Plese tell me, do we need spillback line to prevent compressor surging ?
Thanks for sharing.

[Zauberberg]

How can we answer that without knowing how many compressors are there, of which type, and what control system is in place to maintain the instrument air system pressure? It is virtually impossible to provide you with the correct and complete answer.

Upload a PFD of the system and provide basic data regarding the compressor(s) and the control system, and we can be of more help.

[Padmakar Katre]

Hi,

I understand that the unloader valve means the blow-off valve. Generally in case of centrifugal compressors have the anti-surge control is either achieved through a spill back line (if the gas can't be vented through a blow-off valve), or by a blow-off valve, I have seen commonly in air compressors. So if this is right then you don't need a spill back line. But here I am interested to know the instrument air compressor type, as I have seen those compressors as reciprocating one.

[Art Montemayor]

If this is a serious query, then please follow the advice and request(s) posted by Zauberberg.

Your query is totally lacking in the basic, common data required of all queries:

• What kind of compressor(s) are you talking about? Presumably, you mean a reciprocating positive displacement machine. But if that is the case, what does that have to do with “surging”??? The two subject topics are not compatible.
• Tell us, in detail, what you mean by an “unloader” valve. I think I know, but I am not going to waste time guessing when we should be receiving specific, detailed, accurate information since we are the ones furnishing the free advice and comments.

Our forum awaits your reply.