GAS VOLUME – CHOKE NIPPLE CALCULATION-1

Gas volume is some times determined by flowing through a choke niple . The formula is :

___ ____Q = CP / V GT or Q = 0.003046 C.P / V G.T.

Q = Flow rate MSCFD at 14.4 psia and 60 deg F or 1 atm at 15 deg C.C = Coefficient.P = Upstream pressure , psia . ( gauge reading + 14.7)G = Specific gravity of gas ( Air = 1.0 ).T = Upstream temperature of gas deg R ( deg F + 460 ) or deg K = ( deg C + 273 ).

When the Specific Gravity and temperature are unknown an approximationCan be made by using a Specific Gravity of 0.60 and a temperature of 540 deg R( 80 deg F + 460 ). Or 300 deg K ( 27 deg C + 273 ).

The formula now becomes :

Q = CP or Q = 0.000227 CP 18

COEFFICIENT ( c ) VERSUS CHOKE SIZE

CHOKE SIZE COEFFICIENT. CHOKE SIZE COEFFICIENT. Inch mm

1/8 6.25 3.2 6.253/16 14.44 4.8 14.44¼ 25.51 6.4 26.515/16 43.64 7.9 43.643/8 61.21 9.5 -7/16 85.13 11.1 85.13½ 112.72 12.7 112.725/8 179.74 19.1 260.99¾ 260.99.