Question - Pressure relief valve
Question - Pressure relief valve
(OP)
I work in a gas analysis lab.
3000 psi gas cylinder > pressure regulator (Cv 0.05 to 0.1) to 70 psi depending on gas > manual valve > 1/8" (3 mm) OD metal tubing, 1 m long > my gas analysis instrument.
Per company safety code, I have to install a pressure relief valve in case of pressure regulator failure.
I checked Circle Seal catalog. 1/4" thread, deflector cap, 80 psi crack open, 36 scfm @88 psi, 50 scfm @100 psi. Is this flow sufficient?
Thanks.
3000 psi gas cylinder > pressure regulator (Cv 0.05 to 0.1) to 70 psi depending on gas > manual valve > 1/8" (3 mm) OD metal tubing, 1 m long > my gas analysis instrument.
Per company safety code, I have to install a pressure relief valve in case of pressure regulator failure.
I checked Circle Seal catalog. 1/4" thread, deflector cap, 80 psi crack open, 36 scfm @88 psi, 50 scfm @100 psi. Is this flow sufficient?
Thanks.





RE: Question - Pressure relief valve
Just search flow calculation choked flow or valve flow and this will give you proper value. Don't skimp on this and add a bit for error. Pressure in this system will build in seconds if the regulator fails open and you need a bit of spare.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Question - Pressure relief valve
RE: Question - Pressure relief valve
Something with a wide open Cv of around 0.05/0.06 is usually more than sufficient for a lab analysis type situation (I assume this is a carrier/cal gas application?) and will help reduce the size of relief valve substatially.
We use some instrument regulators that due to their wide open Cv rating (0.138) will usually require a relief valve somewhere around 1" inlet connection when used on natural gas applications (size dependant on process conditions of course).
RE: Question - Pressure relief valve
Yes, the gases are for cal, carrier, fuel for flame ionization detector. Cv 0.02 can give sufficient flow.