Honeywell UMC800 Reference Guide

Function Blocks
Function Block Reference Guide 3/99106
2.38 MSF Function Block
Description
The
MSF
label stands for
Mass Flow Calculation
. This block is part of the
Calculations
category. It looks
like this graphically on the Control Builder.
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 = O
•
If calculation is <= Dropoff, OUT=0, else OUT=Calculation
Continued next page

Honeywell UMC800 Specifications

General

Brand	Honeywell
Model	UMC800
Category	Controller
Language	English