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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.

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Hass Manufacturing Company
371 NY Highway 351, Averill Park, New York 12018 U.S.A.
Tel (518) 674-8151  Fax (518) 674-8157