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Valve Sizing Calculator Please use this form to help select the correct valve for your application. Use the selection as a guide only. Hass Manufacturing Company accepts no responsibility for the acceptability or fitness of use. The equations used are here. Follow these 3 steps: 1. Select your fluid: water, viscous liquid or gas. 2. Enter the information in the form. 3. Press the "Calculate" button when done.  Water Maximum flow rate:   GPM Inlet pressure:   psi Outlet pressure:   psi    Viscous Liquid Maximum flow rate:   GPM Inlet pressure:   psi Outlet pressure:   psi Specific gravity:  Viscosity:   centipoise    Gas Maximum flow rate:   SCFM Inlet pressure:   psia Outlet pressure:   psia Specific gravity:  Temperature:   degrees F    Equations Water Cv = Q / (SQRT (P1 - P2))     (Eqn. 1) Where: Cv = valve sizing coeffecient Q = flow rate in Gallons Per Minute P1 = upstream pressure P2 = downstream pressure Viscous Liquid Turbulent Flow FpCv = (Q/(N1 * Fr)) * SQRT(SG/(P1-P2))     (Eqn. 2) Laminar Flow FpCv = (1/Fs)((Q*U)/(N10*(P1-P2)))^2/3     (Eqn. 3) CvRatio = (Eqn. 2) / (Eqn. 3)     (Eqn. 4) If CvRatio < .46, use Eqn. 3, else use Eqn. 2. Where: Cv = valve sizing coeffecient Q = flow in Gallons Per Minute U = viscosity in centipoise SG = density liquid / density water @ 60F P1 = upstream pressure in psi (psi) P2 = downstream pressure in psi (psi) N1 = 1.0, units constant N10 = 52.3, units constant Fp = 1.0, correction factor for piping around valve (adjust for your conditions) Fr = 1.0, Reynolds factor, turbulent flow Fs = 1.05, valve factor for plug valve Gas Cv = Q/(16.05 * SQRT((P1^2 - P2^2)/(SG * (T+460))))      (Eqn. 5) Where: Cv = valve sizing coeffecient Q = flow in SCFM P1 = upstream pressure in psia P2 = downstream pressure in psia SG = Specific Gravity = density gas / density air at 14.696 psia and 60F T = temperature in degrees F References Hutchison, J.W. ISA Handbook of Control Valves, 2nd Ed. Research Triangle Park, NC: Instrument Society of America, 1976. Technical Bulletin 8, Swagelok Corporation, October 1995.