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Figure 10. Summing Device
5. Time how long it takes for the foam tank to empty. Record the time (in seconds)
and the displayed foam flow rate shown on the control module upper display.
6. Calculate the actual foam flow rate: Take the size of the foam tank (total gallon
volume) divide it by the time it took to empty the tank. For best accuracy
repeat the procedure 2 to 3 times. Ensure there is consistentcy in the result.
(Do not average results that vary greatly from one another.)
Example: (100 gallons/100 seconds) x 60 seconds/minute = 60 GPM
This gives the actual foam flow rate.
7. Compare the displayed flow rate to the actual flow rate. If they differ, go to
step 8 and proceed to calibrate.
8. Locate the calibration potentiometer on the flow summing box for the sensor
being tested (Refer to Figure 10).
9. Loosen the locknut on the correct foam flow calibration potentiometer (pot.)
Use a small screwdriver to adjust the pot. so that the reading in the upper
display on the control module matches the reference flow. Rotating the pot.
clockwise will increase the flow rate and counter clockwise will decrease the
flow rate. Turn the pot. a little bit at a time to allow the computer averaging to
catch up to the new setting (wait for two seconds between adjustments).
10.Repeat steps 1 through 4 and adjust the pot. until the display shows the correct
(actual) foam flow (as determined by the calculation).
11.Unplug the first sensor and plug in the second sensor. Repeat steps 1 through
4 and step 7 for the second sensor.
Calibration Potentiometers for
Foam and Discharge Flow
Interconnecting Cables
Note: For multiple discharge
flow sensors refer to the label
on the summing device for
potentiometer identification.
To Control
Module
To Foam
Flow
Sensor 1
To Foam
Flow
Sensor 2
To Discharge
Flow Sensor
Discharge
Foam 1
Foam 2
12
12
12
12
12
12
12
12
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