Emerson Micro Motion SGM Series - Page 20

Gas measurement when the core process variable is molecular weight (continued)Table 2-4:
Process variable to be reported
Process data from the
meter
Process data from ex-
ternal devices User-specified values
Calorific Value Line density
Specific gravity
% CO
% CO2
% H2
% N2
Wobbe Index Specific gravity
Calorific value
Energy Flow Mass units Line density
Calorific value
Mass flow rate (direct
input or calculated)
Volume units Calorific value Volume flow rate (di-
rect input or calcula-
ted)
(1) Used when you want process variables to represent the gas in the measurement chamber.
(2) Used when you want process variables to represent the gas at the location of the temperature probe.
Gas measurement when the core process variable is relative densityTable 2-5:
Process variable to be reported
Process data from the
meter
Process data from ex-
ternal devices User-specified values
Relative density Relative density
Base density Relative density Base density of air
Line density Temperature data from
meter (RTD)
(1)
Base density
Line compressibility
Base compressibility
External temperature
(2)
Line pressure
Base temperature
Base pressure
Line compressibility Temperature data from
meter (RTD)
(1)
Relative density
External temperature
(2)
Line pressure
% CO2
% H2
% N2
Base compressibility Relative density % CO2
% H2
% N2
Base temperature
Base pressure
(1) Used when you want process variables to represent the gas in the measurement chamber.
(2) Used when you want process variables to represent the gas at the location of the temperature probe.
Orientation and planning
12 Micro Motion
®
Gas Specific Gravity Meters (SGM)