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    CV Flow Coefficients

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API 6D

Bore
(INCHES) 		Classes
150 300 600 900 1500 2500
2 420 420 400 330 330 250
2 1 / 2 690 690 610 520 510 320
3 X 2 200 200 200 190 180 200
3 1200 1050 1000 910 820 500
4 X 3 600 600 600 590 550 560
4 2200 2100 1850 1800 1700 1100
6 X 4 800 800 790 790 780 745
6 5150 5100 4600 4380 3800 2500
8 X 6 2150 2150 2150 2150 2150 2150
8 9500 9400 9000 8500 7400 5300
10 X 8 4300 4300 4450 4450 4100 4100
10 15000 15000 14700 14500 11500 8300
12 X 10 7550 7550 7550 8000 9000 7550
14 X 10 6000 6000 6000 6100 6100  
12 23000 23000 22500 21100 18000 13000
14 X 12 14000 14000 14000 12800 13000  
16 X 12 9100 9100 9100 8900 8900  
14 28000 28000 28000 25000 21000  
16 X 14 15000 15000 15000 14200 14100  
16 37200 37200 37200 34500 27500  
18 21000 21000 21000 19200 19000  
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_1

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)