CV Flow Coefficients – Perfect Engineering Services

API 6D

Bore (INCHES)	Classes
Bore (INCHES)	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: K_v is the metric equivalent of C_v.

K_V = C_V x 0.85

For Liquids:

Where Q_L = Flow in U.S. gallons per minute.
Δ P = (P1–P2) Pressure drop in psi.
G_L = Specific gravity of liquid (water = 1 at 60°F).

For Gases:

Where Q_g = Volumetric flow of gas (SCFH).
G_g = 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)