May 24, 2019

CV Flow Coefficients

API 6D 
Bore
(INCHES)
Classes

150

300

600

900

1500

2500

2420420400330330250
2 1 / 2690690610520510320
3 X 2200200200190180200
3120010501000910820500
4 X 3600600600590550560
4220021001850180017001100
6 X 4800800790790780745
6515051004600438038002500
8 X 6215021502150215021502150
8950094009000850074005300
10 X 8430043004450445041004100
1015000150001470014500115008300
12 X 10755075507550800090007550
14 X 1060006000600061006100 
12230002300022500211001800013000
14 X 121400014000140001280013000 
16 X 1291009100910089008900 
142800028000280002500021000 
16 X 141500015000150001420014100 
163720037200372003450027500 
182100021000210001920019000 
 
 Data for Calculation of Flow 
 The coefficient of flow Cv expresses the rate of flow in gallons per minute at 60°F water with a pressure drop of 1 psig across the valve.The Cv coefficients for the various types and sizes shown in the tables, have been determined from actual flow tests. 
   
 Note: Kv is the metric equivalent of Cv. 
 
KV = CV x 0.85
 
   
 For Liquids: 
 frml_1 
   
 frml_2 
 Where QL = Flow in U.S. gallons per minute.
Δ P = (P1–P2) Pressure drop in psi.
GL = Specific gravity of liquid (water = 1 at 60°F).
 
   
 For Gases: 
 frml_3 
   
 frml_4 
 Where Qg = Volumetric flow of gas (SCFH).
Gg = Specific gravity of gas at standard conditions.
(air at atmosphere and 60°F = 1)
T = Absolute temperature of gas
(°F + 460).
 
   
 Note: For gas, max. ΔP = 1⁄2 P1, and min.
P2 = 1⁄2 P1, and P1, P2 are absolute pressures (psia)
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