K-factors explained
June 2021
SGN-UM-00282-EN-05
Page 14
Example 2
Known values are:
Full Scale Flow Rate
=
85 gpm
Full Scale Output Frequency
=
650 Hz
650 Hz × 60 sec = 39,000 pulses per min
K factor
39,000 pulses per min
85 gpm
458.82 pulses per gallon
=
=
The calculation is a little more complex if velocity is used You first must convert
the velocity into a volumetric flow rate to be able to compute a K-factor
To convert a velocity into a volumetric flow rate, you need to know the velocity
and the inside pipe diameter Also keep in mind that one US gallon of liquid is
equal to 231 cubic inches
Example 3
Known values are:
Velocity
= 4 3
ft/sec
Inside Diameter of Pipe =
3 068 in
Find the area of the pipe cross section.
2
3.068
2
Area = πr
2
Area = π
= π x 2.35 = 7.39 in
2
Find the volume in one foot of travel.
88.71in
2
7.39 in
2
x 12 in. (1 ft)
ft
=
Determine what portion of a gallon one foot of travel represents.
= 0.384 gallons
88.71 in
3
231 in
3
So for every foot of fluid travel, 0 384 gallons will pass
Determine the flow rate in gpm at 4.3 ft/sec.
0 384 gallons × 4 3 fps × 60 sec (1 min) = 99 1 gpm
Now that you know the volumetric flow rate, all you need is the output
frequency to determine the K-factor
