Very basic PRV calcs
Very basic PRV calcs
(OP)
After going through many threads and from my previous knowledge I have a good idea of what is going on, but I would like some concrete calculations to back me up. I am designing a very simple pressure relief valve. It consists of a spring, a disc, and a nozzle. The spring and disc experience atmospheric backpressure here, which is 14psia.
I found that the valve opens up 23psig . If I operate the set up at a high altitude, thus lower atmospheric pressure, 3psia for example, will the valve now open at 14psig? Perhaps I am over simplifying? What would the calcs be?
I found that the valve opens up 23psig . If I operate the set up at a high altitude, thus lower atmospheric pressure, 3psia for example, will the valve now open at 14psig? Perhaps I am over simplifying? What would the calcs be?





RE: Very basic PRV calcs
I2I
RE: Very basic PRV calcs
RE: Very basic PRV calcs
As you wrote in your post "..the atmospheric backpressure here, which is 14 psia.. (needs to be 14.7 psia instead) where psia is "absolute" presssure. For the valve you used "...I found that the valve opens up 23 psig.." psig is "gaged pressure", therefore, the absolute pressure inside the valve was 23+14.7 = 37.7 psia.
In high altitude the gage pressure will still be 23 psig which is determined by the spring load therefore, the absolute pressure inside the valve to open it in high amplitude will be 23+3=26 psia
RE: Very basic PRV calcs
I2I
RE: Very basic PRV calcs
RE: Very basic PRV calcs
I think the following posts may help you :
i) How Back Pressure Affect Conventional PSV Set Pressure Subject to It Vent
ii) Back Pressure Affect Conventional PSV Set Pressure : Case Study #1 - Bonnect Vent to ATM
iii) Back Pressure Affect Conventional PSV Set Pressure : Case Study #2 - Non-Bonnect Vent
JoeWong
Chemical & Process Technology
RE: Very basic PRV calcs
Also, is pressure safety valve the correct term? I have always called them pressure relief valves. Is this to differentiate from something easily confused?
RE: Very basic PRV calcs
RE: Very basic PRV calcs
RE: Very basic PRV calcs
RE: Very basic PRV calcs