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  • Valve flow with given Cv and Inlet Pressure

    Discussion in 'Calculations' started by venividivici, May 14, 2015.

    1. venividivici

      venividivici New Member

      May 2015
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      Good afternoon. I am trying to determine the flow rate of a gas (Methane T=80degF SG=0.6) for a valve that I have selected for my system. I know the inlet pressure (15 PSIG) and the valve Cv (22.5). Looking at the flow equations for gas, it seems I have to first determine if the flow will be critical (choked) or non-critical. Though, to determine this I would first need to know the pressure drop across the valve - which I do not know because I do not know what the flow will be. I have a 2" line that this will be going into. For the type of solenoid valve that I am looking for (2-way, general service, 120VAC, normally closed, and inexpensive) I landed on ASCO's 8210 series. They offer these from 3/8" (Cv of 1.5) up to 2.5" (Cv of 45). I also needed the valve to have a minimal operating pressure differential of 0PSIG (meaning that 0PSIG differential is required for the valve to close). With that being the case, the largest valve of this sort that they offer is an 1.5" (8210G056) with a Cv of 22.5. Is there a way to determine flow of a gas based solely of the inlet pressure and valve Cv? Thank you

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