Point Calculations - Flowmetrics 922-MFC Installation And Operating Instructions Manual

4.4 16 Point Calculations

The 16 Point routine uses the entered data to determine
the K factor for any given input frequency or input flow
signal. This is done by taking the closest data points
above and below the input signal, then using those points
to extrapolate the K factor, then calculating the uncom-
pensated flow from the data. Below are the formulas.
Parameters:
Determine closest point above input signal
signal = X,
Determine closest point below input signal
signal = Y,
Let input signal = H, unknown K factor = KN
To find KN use this formula:
H - Y
x (KA - KB) + KB = KN
X - Y
For example:
Using the values given earlier, with an input frequency of
H = 15 Hz, yields
Determine closest point above input signal
signal = 20 Hz,
Determine closest point below input signal
signal = 10 Hz,
15 - 10
20 - 10
x (1.1111 - 1.25) + 1.25 = 1.18055 = KN
Linearized flow input is
15
1.18055
K factor = KA
K factor = KB
K factor = KA = 1.1111
K factor = KB = 1.25
60
1
x = 762.357 ACFM
KA
KN
KB
4-6
Y H X
Input