Badger Meter MC4000 Diagnostic Test Equipment - Manual (Page 20)

SUPPleMenTArY MeASUreMenTS
Two Point Flow Sensor Calibration Using the New Lin Function
The MC4000 flow sensor output signal is a frequency that is proportional to the rate of flow The MC4000 monitor uses the
frequency information to calculate volumetric flow rate and total flow The raw frequency from the turbine flow sensor
requires scaling by a constant in order to achieve a display reading in the required flow units The MC4000 refers to this
constant as the SCAle defined as follows
SCALE =
Maximum Frequency
Maximum Flow Rate
The MC4000 menu contains two scaling parameters They are the already defined SCAle and a scaling divisor referred to as
the dSCAle
Used to shift the decimal point of the displayed reading, the dSCAle setting is particularly useful when the SCAle parameter is
a very small number such as in the case of small, high frequency turbine flow sensors
Calculated flow readings in the MC4000 use the following formula
Display Reading =
DSCALE
Input Frequency x SCALE
example
A typical 1 in turbine flow sensor would have the following characteristics
Maximum Flow = 80 gpm
Maximum Frequency = 765 Hz
The scale factor, SCAle, calculation is:
SCALE =
765 Hz
80 gallons
= 0.1046
The value for this sensor entered into the SCAle parameter would be 0 1046 In this case a dSCAle value of 1 000 would give
correct readings on the MC4000 display
Using a larger value for dSCAle offers higher resolution and is especially useful when the SCAle value has several leading
zeroes in it
example
A small turbine flow sensor has the following full scale values
Maximum Flow = 7 gpm
Maximum Frequency = 2632 Hz
SCALE =
2632 Hz
7 gallons
= 0.0026596
Because of display limitations, better results are obtained by multiplying the SCAle value by 1000 and using a dSCAle value
of 1000
Page 20 Month 2014