Pressure Reducing & Relief Valve

[ema]

Hi everyone!

Is there a possibility to use an existing pressure reducing valve as a relief valve with some small modifications? Or they are totally different in construction? We have one old pressure reducing valve installed on a water supply pipe line but we have installed a new well pump just upstream of this valve. What I want to do is to use this valve as a relief valve to simulate the well pump as it is pumping against a constant pressure (i.e. up to a reservoir). Do we need to change this valve or just a small modification will serve our purpose? Any help will be very much appreciated!

 

[davefitz]

There is a formal answer and a less formal answer.

Informally, if your only purpose is to test the performance of a pump and not to protect from overpressure failure, then, yes you can use a PRV ( pressure reducing valve) . But you also have to meet all the requirements of the piping code for which the project is liable , which likely means the piping must be of a design pressure greater than the pump dead head pressure plus max pump inlet pressure head, or suitable safety relief valves must be provided to prevent the piping from overpressure failure.

Different codes treat pressure relief via PRV differently. Section I allows once-thru steam generators to be partially protected by PRV's and partially protected by safety valves plus automatic trip of the fuel and water. B31.1 allows overpressure protection of fuel gas piping systems by the use of dual, independent, redundant PRV's in series plus pressure switches hardwired to a fast stop valve in lieu of safety valves. And other codes only permit the use of safety valves and give no credit to PRV's. The German boiler code TRD allows some boilers to be protected using only special PRV's and no safety valves.

 

[ema]

Thanks for your reply.