Liquid Controls IT375 - Manual (Page 10)

Sponsler, Inc. Model IT375 Operation Pg. 10
3.6 FREQUENCY CUTOFF
A frequency cutoff can be programmed below which flow rate is not registered.
Input frequencies at or below the cutoff are totalized, however, the rate is displayed as zero.
The frequency cutoff has a default value of 0.25Hz. The cutoff should be left as 0.25Hz unless the flowmeter in use has
a lower frequency.
Note that the lower a cutoff frequency the correspondingly longer response time for flow rate to update. For example, if
the cutoff is set to 0.01Hz the Model IT375 will continue to display the flow rate for 100 seconds even if the signal
stops. This is because a cutoff frequency of 0.01Hz means that the time interval between signals is 100 seconds (period
= 1/frequency), therefore, the Model IT375 must wait 100 seconds before it can determine that the flow has actually
stopped.
3.7 LINEARIZATION
The following diagram graphs the change in K-factor with frequency for a hypothetical flowmeter. The heavy
black line represents the actual K-factor of the flowmeter, while the light black line is the approximation
used in the instrument.
Up to 10 frequencies and K-factors can be programmed. Frequencies must be programmed in ascending
order. Linear Interpolation is used between points. If an input frequency is less than the first (lowest) or
greater than the last (highest) programmed frequency, the K-factor will remain a constant value.
Note: Display update time increases to 1sec if the linearizer is enabled in the battery powered version
of the Model IT375.
Scaling Factor
Out 1
Out 2
Out 3
Out 4
Out 5
Frequency
0 Inp 1 Inp 2 Inp 3 Inp 4 Inp 5