Msf Mass Flow Calculation Function Block - Honeywell HC900 Reference Manual

Function Blocks

MSF Mass Flow Calculation Function Block

MSF Mass Flow Calculation Function Block
Description
The MSF label stands for Mass Flow Calculation.
This block is part of the Calculations category.
Function
Calculates gas mass flow (OUT) from differential pressure input value (X) that represents a pressure drop
across an orifice plate (for example). It accepts two other inputs to include pressure (Y) and/or temperature
(Z) compensation in the calculation. The calculation includes square root extraction.
•
OUT = Kq
*
Kq =
dP =
=
P =
=
T =
=
If calculation is <= Dropoff, OUT = 0, else OUT = Calculation
•
216
sqrt [(dP P) / T]
*
Orifice Constant
Differential pressure which
(Kx X) + Bx; where:
*
Kx = Delta pressure scaled for desired engineering units
X = Analog input value
Bx = Delta pressure bias in desired engineering units
Absolute gas pressure which
(Ky Y) + By; where:
*
Ky = Pressure scaler for desired engineering units
Y = Gas pressure analog input value
By = Pressure bias in desired engineering units
Absolute gas temperature which
(Kz Z) + Bz; where:
*
Kz = Temperature scaler for desired engineering units
Z = Gas temperature analog input value
Bz = Temperature bias in desired engineering units
If (Kz Z) + Bz = 0, then: OUT = 0
*
HC900 Hybrid Control Designer Function Block Reference Guide Revision 11
2/07