Dynasonics DXN Portable Ultrasonic Measurement System - Manual (Page 103)

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.
r 2 π
Area =
3.068
2
= 2.353 = 7.39 in
2
2
x
π
Find the volume in 1 ft of travel.
7.39 in 12 in (1Ft.) =
88.71 in
ft
2
3
x
What portion of a gallon does 1 ft of travel represent?
88.71 in
231 in
= 0.384 gallons
3
3
So for every foot of fluid travel 0.384 gallons will pass.
What is the flow rate in gpm at 4.3 ft/sec?
0.384 gallons 4.3 FPS 60 sec (1 min) = 99.1 GPM x x
Now that the volumetric flow rate is known, all that is needed is an output frequency to determine the K-factor.
Known values are:
Frequency = 700 Hz (By measurement)
Flow Rate = 99.1 gpm (By calculation)
700 Hz × 60 sec = 42,000 pulses per gallon
K-factor =
42,000 pulses per min
99.1 GPM
= 423.9 pulses peer gallon
Installation & Operation Manual
Page 103 February 2013