About Flow Rate Conversions
Design calculations have been made using the following unit convention factors to maintain design consistency
Normal flow, Normal Cubic Meters per Hour, (Nm3/hr)
Normal Conditions are defined as: Tn = 20.0 C, (68 F) Pn = 1.01 bara, (14.72 psia)
Note: the definition of Normal conditions are consistent with the calibration of the CME.
Standard flow, Standard Cubic Feet per Minute, (SCFM)
Standard Conditions for the calculation of SCFM are defined as: Ts= 15.6 C, (61 F) Ps= 1.01 bara, (14.72 psia)
Note: the definition of Standard conditions are consistent with the calibration of the CME.
Standard flow, Standard Liters per Minute, (SLPM)
Standard Conditions for the calculation of SLPM are defined as: Tn= 0 C, (32 F) Pn= 1.01 bara, (14.72 psia)
Note: the definition of SLPM conditions are consistent with the calibration of the CME.
Standard flow, Standard Cubic Centimeters per Minute, (SCCM)
Standard Conditions for the calculation of SCCM are defined as: Tn= 0 C, (32 F) Pn= 1.01 bara, (14.72 psia)
Note: the definition of SCCM conditions are consistent with the calibration of the CME.
Conversion basis and Flow Concerversion Table shows the calculation basis for the flow rate conversions as used by SAES Pure Gas.
Note: Ratios toward the right side of the Figure are acutal conversion used in the Crane Companion

Flow calculations using definitions from SAES Pure Gas, Inc.:
Standard flow, SCFM
Ts = 61 deg F pV = mRT
Ps = 14.696 PSIA m = 0.07374 lbm per SCF
R = 55.12 (ft lbf)/(lbm deg R) 0.22603 SCFM per lbm
M = 28.0134 mol/mol 6.33176 SCFM per (lb mol)/hr
Gas = Nitrogen
Nm3/SCFM = 1.71928
SCFM/Nm3/hr = 0.58164
Normal flow, Nm3/hr
Tn = 20 deg C
Pn = 14.72 PSIA pV = mRT
Pn = 101490.8 Pa m = 1.16726 lbm per Nm3
R = 296.6 J/(kg deg K) 0.3886 Nm3/hr per lbm
M = 28.0134 10.88605 Nm3 per (lb mol)/hr
Gas = Nitrogen
Nm3/SLPM = 0.0644
SLPM/Nm3/hr = 15.5275
Standard flow, SLPM
Ts = 32 deg F pV = mRT
Ps = 14.72 PSIA m = 0.00276 lbm per SL
R = 55.12 (ft lbf)/(lbm deg R) 6.03401 SLPM per lbm
M = 28.0134 mol/mol 169.0333 SLPM per (lb mol)/hr
Gas = Nitrogen

© 2014 Rainer Lammertz