Flow Rate Restriction
Flow Rate Restriction
(OP)
I have a low pressure nitrogen gas system supplied from a 3000 psig source through a regulator. The regulator output flows through 6 feet of 1/4" diameter hose to the low pressure components. To limit the low pressure system pressure to 80 psig, the designer used a relief valve.
Problem. The full flow rate of the relief valve is less than that of a failed regulator. I need a method to limit flow to about 5-6 scfm. For a 3000 psig inlet pressure and 2950 psig pressure drop, the Cv is on the order of 0.001 but the Cv for a 0.03" orifice is only 0.016. Too many orifices. Needle valve maybe?
Any suggestions are welcome.
Problem. The full flow rate of the relief valve is less than that of a failed regulator. I need a method to limit flow to about 5-6 scfm. For a 3000 psig inlet pressure and 2950 psig pressure drop, the Cv is on the order of 0.001 but the Cv for a 0.03" orifice is only 0.016. Too many orifices. Needle valve maybe?
Any suggestions are welcome.





RE: Flow Rate Restriction
Different PSV maybe? 80 psig should be enough pressure to get 5 to 6 scfm even at 1/4" (though I will admit I haven't crunched any numbers). I've seen Swagelock spring loaded check valves used as PSVs in some service, have you looked at something like that?
RE: Flow Rate Restriction
RE: Flow Rate Restriction
Is your application precharging pulsation damper bladders on suction of a pump?
RE: Flow Rate Restriction
RE: Flow Rate Restriction
RE: Flow Rate Restriction
I'll keep the check valves in mind should I need to increase the relief flow rates rather than restrict the inlet flow.
RE: Flow Rate Restriction
RE: Flow Rate Restriction
You might want to look at FAQ798-1196 on how to calculate the choked flow of a gas through a restriction orifice.
Milton Beychok
(Visit me at www.air-dispersion.com)
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