Honeywell HC900 - MSF Mass Flow Calculation Function Block

Function Blocks
MSF Mass Flow Calculation Function Block
216 HC900 Hybrid Control Designer Function Block Reference Guide Revision 11
2/07
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
*
sqrt [(dP
*
P) / T]
Kq = Orifice Constant
dP = 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
P = 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
T = 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
• If calculation is <= Dropoff, OUT = 0, else OUT = Calculation