Cv: Valve flow coefficient
Q: Volumetric flow rate (scfh)
N7: Numerical constant (1360)
Y: Expansion Factor
Y = 0.667 when P2 <= 0.5 * P1 for choked or critical flow
Y = 1.0 when P2 > 0.5 * P1 for very low pressure differential
P1: Upstream absolute static pressure (psia)
P2: Downstream absolute static pressure (psia)
T1: Absolute upstream temperature (R)
Gg: Gas specific gravity
X: ratio of pressure drop to absolute inlet pressure
| Cv | ||
| Q | ||
| N7 | ||
| Y | ||
| P1 | ||
| P2 | ||
| T1 | ||
| Gg | ||
| X |
ISA 75.02 Control Valve Capacity Test Procedures