Fluid Components International MT91 Manual Operation - Manual (Page 14)

FLUID COMPONENTS INTL CHAPTER 3 - OPERATION
Model MT91 Multipoint Flowmeter 3 - 14 Doc. No. 003185 Rev. B
Application of the correction equation will be illustrated in the following example. Through analysis of the process
flow stream it is determined that the flow rate must be multiplied by 1.056 to output the desired value. The
correction equation takes the following form.
Example:
m m m m m
new
= + Ч + Ч + Ч = Ч
0 1 056 0 0 1 056
0 0
2
0
3
0
( . ) ( ) ( ) .
where C
1
= 0
C
2
= 1.056
C
3
= 0
C
4
= 0
A more complicated situation would be where the multiplication factor varies with the flow rate. Figure 3-9 shows
the variation of desired flow rate versus the measured flow rate.
Measured Flow Rate
Desired
Flow Rate
0
10
20
30
40
50
0 20 40 60
C00248-1
Figure 3-9. Desired Flow Rate Versus Measured Flow Rate
The relationship between the measured and the desired flow rates was determined through a least squares analysis.
The coefficients for the above relation are:
C
1
= -7.5672 C
2
= 2.09253
C
3
= -0.037082 C
4
= 0.0003505
Ø To enter the correction equation coefficients and enable it:
1. Go to menu level 2.2.5 (Setup Þ Outputs Þ Corrections).
2. Press 2=Enter Correction. Enter the user password (if it enabled).
3. Enter all the desired coefficients. When complete, press 6=Verify and Save. Scroll through the displayed
coefficients then save them if they are correct.
4. Press ENTR and then 1=Enable. Select 1=Enable or 2=Disable.
Offset Adjustment of Sensing Points
Using the offset adjustment allows the customer to shift the calculated flow rate up or down to agree with another
reference instrument. FCI uses a balanced order polynomial equation to map the sensing point information to a
curve. The general form of this equation is shown below.
Flow C R C R C C R C R
= + + + + − −
1 2 3 4 5 2 1 2 ( ) ( ) ( ) ( )
∆ ∆ ∆ ∆