3 replies to this topic

[chem101]

Hi everyone,

Just a quick question. Is it possible yo have reverse flow by sudden closure of a valve?

what i mean is that, If there is liquid flowing in a pipe and suddenly the flow or pressure control valve closes, would this cause a reverse flow. This question was raised in HAZOP study. Process engineer was in the opinion of no flow, because he said sudden valve closure will cause hydraluic shock but not reverse flow, with which we did not agree. I like to hear your opinion in this case.

 

Thank you very much

[fallah]

chem101,

 

In general, following to sudden closure of a control valve in a liquid line there would be the possibility of reverse flow might lead to pressure surge...

[ankitg009]

Hydraulic shock is the term used to describe the momentary pressure rise in a piping system which results when the liquid is started or stopped quickly. 

 

Fluid always flows from high pressure to low pressure. If pressure developed due to hydraulic shock is greater than the source pressure+pressure drop due to friction+pressure due to static height(if any), than yes there will be reverse flow. 

[shan]

If your check valve is specified to handle the pressure differential due to the control valve sudden closing, it should not have reverse flow from server check valve leakage unless the check valve is failed.