ORBIT-2中文版(20)

压力测试和压降计算公式

压力测试（ ASME B16.34*, API 6D*）

压力测试时间

* For valves of WCC material. Times shown are for API 6D valves

ASME B16.34 valves test times are less than values shown.

For each Orbit valve there is a flow coefficient CV . This is defined as the flow in gallons per minute of water at 60°F with apressure drop of 1 psi across the valve. By using the following simplified formulas, the pressure drop for a given set of flow conditions may be calculated: (Refer to Bulletin FCI 62-1 of Fluid Controls Institute, Inc. for additional information.)

FOR LIQUIDS:

ΔP= G(Q/C )V

2

FOR GASES:

ΔP= 541 x 10

-9

P( )

V2

ΔP =psi Drop across valve

G = Specific gravity of liquid (water = 1.0) Q = Flow in gpm

CV = Valve coefficient (GPM water flow at

1 psi pressure drop across valve at 60°F)

ΔP=psi Drop across valve

G = Specific gravity (air @ 14.7psi & 60°F = 1.0) T = Absolute temperature (F + 460)

P = Line pressure psia (psi absolute - psi Gage + 14.7)

Q = Flow standard cubic feet per hour @ 14.7 psi and 60°F CV = Valve coefficient (GPM water flow at

1psi pressure drop across valve at 60°F)

18 ORBIT

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