Emerson Micro Motion SGM Series - Equations Used to Calculate Specific Gravity, Molecular Weight, and Relative Density

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.
Specific gravity Equation 2-1:
SG = K0 + K1 ×  + K2 × 
2
SG
Specific gravity of process gas
K0, K1, K2
Calibration factors from the on-site calibration. If a two-point calibration was
performed, K1 is set to 0.
τ
Sensor time period (microseconds)
Molecular weight calculated from specific gravity Equation 2-2:
MW
Gas
= SG
Gas
× MW
Air
MW
Gas
Molecular weight of process gas (g/mol)
SG
Specific gravity of process gas
MW
Air
Molecular weight of air (user-specified; default = 28.96469 g/mol)
Core process variable = Molecular weight
The following equations are used when the core process variable is molecular weight.
Molecular weight Equation 2-3:
MW = K0 + K1 ×  + K2 × 
2
MW
Molecular weight of process gas
K0, K1, K2
Calibration factors from the on-site calibration. If a two-point calibration was
performed, K1 is set to 0.
τ
Sensor time period (microseconds)
Orientation and planning
Configuration and Use Manual 13