13.7.1 Equations used in user-defined calculations
Each user-defined calculation has an equation and a set of user-programmable constants
and/or user-specified process variables.
User-defined calculation 1 (square root) Equation 13-1:
=A + B ×
× + X ×
× + Y ×
A, B, X, Y
User-programmable constants
a, b, c, d, e, f
User-programmable constants or user-specified process variables
y
Result of calculation
User-defined calculation 2 (exponential) Equation 13-2:
= e
A+ B×t + C × t
2
e
Natural logarithm
A, B, C
User-programmable constants
t
User-programmable constant or user-specified process variable
y
Result of calculation
13.7.2 Measurement units used in user-defined calculations
The meter's internal measurement units are used for all process variables referenced by a
user-defined calculation. All constants must be entered in the internal measurement units
or derived using the internal measurement units.
Process variables and internal measurement unitsTable 13-1:
Process variable Internal measurement unit
Density g/cm³
Referred Density g/cm³
Relative Density g/cm³
Molecular Weight g/mol
Calorific Value MJ/kg
Mass Flow (external or calculated) kg/sec
Volume Flow (external or calculated) l/sec
Energy Flow MJ/sec
Line Temperature °C
External Temperature °C
Measurement support
142 Micro Motion
®
Gas Specific Gravity Meters (SGM)