Capacity | Gas Regulator
For critical flow: (P outlet absolute ≤ ½ P inlet absolute)
CAPACITY INFORMATION
Q = P C g * 1.29
For subcritical flow: (P outlet absolute > ½ P inlet absolute)
Table D provides the natural gas regulating capacities of the 7333 regulators at specific inlet pressures and outlet pressure settings. Flows are in SCFH (60°F and 14.7 psia) of 0.6 specific gravity gas. For specific gravity conversion factors to other gases, refer to Table A. To determine regulating capacities at pressure not given on Table D, or to find wide-open flow capacity of regulator for relief sizing, use the following formula.
) P P
(
√
√
3417 C 1
520 GT
Q =
C g P sin
*
= See Table C = See Table C
C g C 1 G
= gas specific gravity (air = 1.0)
P
= inlet pressure, psia = flow rate, SCFH
Q
T
= absolute temperature of gas at inlet in ºRankine = differential pressure, psi (The difference between the regulator inlet pressure and the maximum outlet pressure that can be tolerated by downstream com- ponents)
P
Table B. Maximum and Minimum Differential Pressures
Maximum Allowable Differential Pressure Minimum Differential Pressure for Full Stroke
Body Size
NPS
DN
psig
bar
psig
bar
2 3 4 6
50 80
125 125 125 125
9 9 9
5 6 8
0 0 1
100 150
8.6
19
1.3
Table C. Flow Coefficients for 7333
Valve RCY. CO EFF
NPS DN Regulating Wide-Open Regulating Wide-Open C1 Regulating Wide-Open Regulating Wide-Open C 1 Km 2 50 2280 2400 63.3 66.7 36.0 2050 2160 59.6 62.8 34.4 0.70 3 80 4630 4880 132 139 35.1 4410 4650 128 135 34.4 0.70 4 100 7320 7710 202 213 36.2 6940 7310 198 209 35.0 0.70 6 150 12900 13600 397 418 32.5 12100 12800 381 404 31.7 0.7 Body Size Cg Cv Cg Cv 1:1 Outlet Line Size to Body Size 2:1 Outlet Line Size to Body Size
* Use regulating CG to find regulating capacity or wide open CG to find wide open capacity.
Bulletin 7333 Page 3
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