Units Constant "K" for gas flow

To eliminate the need to convert pressure and flow parameters into specific units such as "psia" and "std L/min.", the table below lists values of the Units Constant "K", which is used in the Gas Flow Lohm Formulas:

 
(Sonic: P1/P2 ≥ 1.9)   (Subsonic: P1/P2 < 1.9)

 

Units Constant "K" for Volumetric Flow

Abs. PrespsiaBar kPamm.Hg
FlowSLPMSCFM in3/minSLPMSCFMSLPMmL/min
H2103036.362,70014,90052614919,900
He77127.247,10011,20039511214,900
Neon34312.120,900498017649.8 6640
Nat. Gas31911.319,400462016346.26160
N22769.7316,800400014140.05330
CO2749.6916,700398014139.85300
Air2719.5616,500393013939.35230
Ethane2518.8615,300364012936.44850
O22579.0815,700373013237.34970
Argon2458.6514,900355012535.54730
CO22137.5213,000309010930.94110
N2O2147.5613,100310011031.04140
SO21766.2110,700255090.125.53400
Freon-121234.34 7510178063.017.82380

Units Constant "K" for Gravimetric Flow

Abs. PrespsiaBarkPamm.Hg
FlowPPH lbm/s kg/min.PPH kg/min. kg/min. gm/min.
H211.60.003220.08761681.270.0127 1.69
He17.30.004790.1312501.890.01892.52
Neon38.70.01080.2935614.250.04255.66
Nat. Gas34.80.009660.2635053.820.03825.09
N243.20.01200.3266264.730.04736.31
CO43.00.0119 0.3256234.710.04716.28
Air43.80.01220.3316364.810.04816.41
Ethane42.20.01170.3196114.620.04626.16
O246.00.01280.3486675.040.05046.72
Argon54.60.01520.4137925.990.05997.99
CO252.40.01450.3967595.740.05747.65
N2O52.70.01460.3987645.770.05777.70
SO263.00.01750.4769146.910.06919.21
Freon-1283.20.02310.62912109.120.091212.2

 

EXAMPLE: A restrictor must flow 8.20 std L/min. of helium at room temperature (70°F), with an inlet pressure of 1,500 kPa, discharging to atmosphere. What Lohm rate is required?

K = 112 (see pages S18-19)
T1 = 70°F. , fT = 1.00 (see page S17)
P1 = 1,500 kPa, P2 = 101 kPa
P1/P2 = 14.9 (sonic)

EXAMPLE: A restrictor must flow 0.0015 lbm / s of oxygen at room temperature (70°F), with an inlet pressure of 1,200 psia, discharging to 850 psia. What Lohm rate is required?

K = 0.0128 (see pages S18-19)
T1 = 70°F , fT = 1.00
P1 = 1,200 psia. , P2 = 850 psia.
P1/P2 = 1.41 (subsonic)
ΔP = 350 psid.
w = 0.0015 lbm / s

 

<< Engineering Data