Electronics International FL-1 - Manual (Page 13)

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Calibration Issues: Calibration Issues: Calibration Issues: Calibration Issues: Calibration Issues:
The FL-1 must be calibrated in gallons. Liters are calculated from gallons using a x3.75 factor. Pounds
are calculated from gallon using a x6.0 factor. The FL-1 can be calibrated for a 4 gallon tank or as large as
999 gallon tank.
The FL-1 can be calibrated with as few as two points (full and empty) or as many as 9 points. The
calibration points provide the FL-1 with a fuel sensor output for a specific fuel level. The output of a fuel
sensor will be resistance for a resistive fuel probe or a frequency for the Electronics International capacitive
probe. In either case, the output of the fuel probe is converted to an arbitrary count we call “Sensor
Counts."
As the fuel level in the fuel tank increase, the Sensor Counts displayed on the FL-1 will increase
(provided you have programmed the FL-1 with the proper operating mode). Some common problems with
fuel tanks are listed below:
1. As you add fuel to an empty tank, it will take a certain amount of fuel before the resistive float starts
to move off the bottom of the tank or off the bottom end stop. For a capacitive system, it takes a
certain amount of fuel to reach the center electrode. Fuel levels below this point cannot be mea-
sured.
2. As you add fuel and the fuel level nears the top of the tank, the float on a resistive sensor will hit the
top of the tank or the top end stop. For a capacitive system, the fuel level will exceed the center
electrode. The fuel above this point cannot be measured. Therefore the FL-1 may not read a full
tank.
These problems can cause accuracy issues for any system. To improve the accuracy of the FL-1, we
recommend you set 5 calibration points, empty, ¼, ½ , ¾, and full. By doing this, any issues at the full or
empty fuel levels will not effect the accuracy between the ¼ and ¾ fuel levels.
Another common problem with fuel gauges is they may not display a full tank after calibration. If the
FL-1 has this problem, slightly reduce the Sensor Counts for the full fuel level calibration point. To calcu-
late how much to reduce the counts, divide the change in the Sensor Counts between two cal points (near 1/
2 tank) by the change in the fuel level between the same two cal points. The FL-1 allows you to change the
fuel level or the Sensor Counts for any calibration point without having to add or remove fuel from the tank.
You can also recalibrate any calibration point at any time.