Max flow calculation for choosing PSV
Max flow calculation for choosing PSV
(OP)
This is the case i am dealing with:
A 2" pipe connecting a pressure vessel (200.5 psia) to a pump. The pump is designed to fill and evacuate the cold and not pressurized fluid. I must protect the pump from 145 psia. In case of leaking (or open from some reson) 2" valve there will be high pressure flow to the pump.
I took worst case scenario for gas flowing through 2" pipe in sonic velocity and calculated the volume flow from pipe flow area and the velocity.
I am getting very large PSV for 2" pipe.
P=200.5 psia
T=287 oF
Tb= 97oF @ atm.
Vsonic=164 m/s
A 2" pipe connecting a pressure vessel (200.5 psia) to a pump. The pump is designed to fill and evacuate the cold and not pressurized fluid. I must protect the pump from 145 psia. In case of leaking (or open from some reson) 2" valve there will be high pressure flow to the pump.
I took worst case scenario for gas flowing through 2" pipe in sonic velocity and calculated the volume flow from pipe flow area and the velocity.
I am getting very large PSV for 2" pipe.
P=200.5 psia
T=287 oF
Tb= 97oF @ atm.
Vsonic=164 m/s





RE: Max flow calculation for choosing PSV
RE: Max flow calculation for choosing PSV
I couldn't tell if the pump is set up to suck on the vessel or fill the vessel. If it is to fill the vessel (for example), then putting two swing checks in the line would make sonic velocity non-credible (since both would have to fail for the scenario to play out).
Bottom line is that you don't have to use worst-case conditions, you should use worst-credible conditions which are generally more reasonably sized valves.
David
RE: Max flow calculation for choosing PSV
Zdas04, This is a filling evacuation system. Swing checks valve of any kind will cause a problem. Do you think double block by gate or ball is enough to make this case "non credible"?
RE: Max flow calculation for choosing PSV
Does the line really need to be full, 2-inch? If not you could put a smaller choke nipple in the line that would significantly reduce the flow rate required by the PSV.
David
RE: Max flow calculation for choosing PSV