Relief valves
Relief valves
(OP)
Hi everybody, I found that in most cases these kind of valves have an outlet with littler flange rating and bigger diameter than the inlet, I ask you why. Maybe the rating is for the pressure reduction but I really can't explain the bigger diameter.
Many thanks
Many thanks





RE: Relief valves
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Relief valves
Mike McCann
MMC Engineering
RE: Relief valves
I2I
RE: Relief valves
Remember the Fluids and Thermodynamic courses you have undertaken as a chemical engineer and the answer stares you in the face. The fundamental requirement of a relief valve is to releive pressure. In doing so the pressure at the outlet of the valve is less than the pressure at the inlet and if we consider the event to adiabatic then using P1V1=P2V2 the volume must increase hence the requirement for a larger outlet. (i.e. to get the stuff out more easily!!)
RE: Relief valves
Types of downstream choking that would derate the valve include frictional choking ( fL/d of exhaust piping), and acoustic choking ( flow area together with oblique shock waves that occur at elbows). To avoiod this latter choke effect, the outlet el needs to be a couple of pipe sizes greater than the valve seat .
RE: Relief valves
RE: Relief valves
Can anyone tell me when putting the outflow from the Pressure relief valve back into the inlet of the pump is acceptable?
Thanks
RE: Relief valves
RE: Relief valves
Thanks
RE: Relief valves
In some cases, such a recirc relief valve resullts in high fluid temperature and overheat of the pump.
RE: Relief valves
Thanks alot
RE: Relief valves
David
RE: Relief valves
Johnny Pellin
RE: Relief valves
I have seen folks try to use PSV (pressure safety valves) in place of PRV (pressure reducing valves) for recirculation with bad results. PSVs are not intended for throttling applications. PSVs typically open too quickly and slam shut as well resulting in chatter that creates valve seat damage.
RE: Relief valves
Please start a new thread, if somebody wants to continue this.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Relief valves
RE: Relief valves
SMIH dragged us into the weeds, the rest of us are just following. I can't believe that none of us caught the first off-topic post, but we didn't seem to.
David
RE: Relief valves
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Relief valves
OK. Back to basic question.
The solution you describe is most commonly found on the market for the most common gas/liquid two phase (and single phase gas) used as heat and power carrying fluid: water steam with its condensate water.
Steam will as other gases expand when exposed to lower pressure, and likewise might condensate flash to steam of greater volume if released at lower pressure.