Equations Used To Calculate Specific Gravity, Molecular Weight, And Relative Density - Emerson Micro Motion SGM Series Configuration And Use Manual

2.4 Equations used to calculate specific gravity,
molecular weight, and relative density
Core process variable = Specific gravity
The following equations are used when the core process variable is specific gravity.
Equation 2-1:
SG
K0, K1, K2 Calibration factors from the on-site calibration. If a two-point calibration was
τ
Equation 2-2:
MW
Gas
SG
MW
Air
Core process variable = Molecular weight
The following equations are used when the core process variable is molecular weight.
Equation 2-3:
MW
K0, K1, K2 Calibration factors from the on-site calibration. If a two-point calibration was
τ
Configuration and Use Manual
Specific gravity
SG = K0 + K1 × � + K2 × �
Specific gravity of process gas
performed, K1 is set to 0.
Sensor time period (microseconds)
Molecular weight calculated from specific gravity
MW
Molecular weight of process gas (g/mol)
Specific gravity of process gas
Molecular weight of air (user-specified; default = 28.96469 g/mol)
Molecular weight
MW = K0 + K1 × � + K2 × �
Molecular weight of process gas
performed, K1 is set to 0.
Sensor time period (microseconds)
2
= SG × MW
Gas Gas Air
2
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