Emerson Process Management ControlWave XFC - Manual (Page 128)

F-26 / Appendix F CI-ControlWave XFC
Low Flow Cut Off - When the differential pressure drops below the low flow cut off value,
the flow rate will be set to zero. Default units are “inches of water.”
Orifice Diameter - Orifice diameter is entered here. Default units are “inches.”
Pipe Diameter - Diameter of the pipe is entered here. Default units are “inches.”
Orifice Constant - K (AGA3 1985) - Orifice constant is entered here.
Adjust Press. - Users enter Average Barometric Pressure here.
Diff. Pressure - Actual value of Differential Pressure (Inches H
2
O) are displayed here.
Static Pressure - Actual value of Static Pressure (psig) are displayed here.
Temperature - Actual value of Temperature (Deg. F) are displayed here.
Specific Gravity - Specific Gravity of the gas being measured is displayed here.
Figure F-18A - (1985 AGA3) Orifice Flow Equation Setup Web Page
FPV - Supercompressibility Factor (FPV) is displayed here.
Base Temperature - Required or Contract Base Temperature is entered here (Deg. F).
Base Pressure - Required or Contract Base Pressure is entered here (psig).
The following outputs from the AGA3 calculation are displayed:
MSCF/H - Flow rate in thousands of standard cubic feet per hour
Low Flow Cut Off - Cutoff (if the DP drops below the low flow cut off value) or OK
C Prime - Orifice Flow Constant
Fb - Basic Orifice Factor