Calculation of mass flow rate to volumetric flow
Most of the Vacuum pumps are rated for Volumetric displacement while the processes specify in mass flow rates / Throughputs. The following expression gives a relationship between the two for precise selection of booster.
Based on the fundamental gas laws PV= RT, an expression can be derived for Volumetric Flow Rates required for pumping different vapors/gases. Based on the Mass flow rates one can estimate the pump capacity required.
V = R. Tgas / P Q1/M1 + Q2/M2 …………. Qn/Mn
Where
V = Inlet Volume flow rate m3/hr.
R = Universal gas Constant, 83.14 mbar m3/ Kgmol x ºK
Tgas = Gas/Vapor abs. Temp, in ºK
P = Process Absolute Pressure in mbar
Q1, Q2, Q3 = Gas / Vapor flow rate, in Kg/hr.
M1, M2, M3 = Molar mass, in Kg/mol. of gas /vapor.
Most of the Vacuum pumps are rated for Volumetric displacement while the processes specify in mass flow rates / Throughputs. The following expression gives a relationship between the two for precise selection of booster.
Based on the fundamental gas laws PV= RT, an expression can be derived for Volumetric Flow Rates required for pumping different vapors/gases. Based on the Mass flow rates one can estimate the pump capacity required.
V = R. Tgas / P Q1/M1 + Q2/M2 …………. Qn/Mn
Where
V = Inlet Volume flow rate m3/hr.
R = Universal gas Constant, 83.14 mbar m3/ Kgmol x ºK
Tgas = Gas/Vapor abs. Temp, in ºK
P = Process Absolute Pressure in mbar
Q1, Q2, Q3 = Gas / Vapor flow rate, in Kg/hr.
M1, M2, M3 = Molar mass, in Kg/mol. of gas /vapor.