Centroid Products
2104 HIBISCUS DR.  -    EDGEWATER, FL   32141
TEL: 386-423-3574   -   FAX:  386-423-3709


Computerized Tank Monitoring System
For Fuel, Oil, and Potable Water Tanks

Sensor Preparation
(Skip to installation if your unit is custom built.)

The fuel probe is constructed of concentric aluminum tubing (one small tube inside another) that are separated by small spacers press fit on the small inner tube.

Measure the depth of your tank from the outside top to the tank bottom.  The probe should be cut so it is 1/4 or more inches from the tank bottom. It is recommended to be 1 inch or more on deeper tanks to keep the probe out of sludge buildup or give a more accurate reading for v-shaped tanks.

fuel probe
A tubing cutter or hacksaw can be used to cut the outside tube. Be careful not to get any metal filings or debris inside the tubing.


probe calibration


Your unit is calibrated at the factory prior to shipment.  Recalibration will be required if you have to cut your unit to fit your tank, otherwise a minor adjustment of the FULL screw is all that may be necessary to match the actual full level in your tank.

Make the wiring connections as depicted on the wiring diagram.

1.  Be sure the unit is dry before you attempt to calibrate.  Residual liquid left inside the tube will give an erroneous reading and affect the calibration.  If the unit has been in liquid, shake out the residual liquid before you attempt to calibrate.

2.  With the probe out of the liquid, turn the FULL and EMPTY adjustment to the full CW (clockwise) position.

3. Turn on the ignition switch---slowly turn the EMPTY screw CCW (counter clock wise) until the display indicates 0 volts (empty).  DO NOT ADJUST ANY FURTHER.

4. Immerse the probe in a full tank of liquid, adjust the FULL screw CCW until the display reads 4 volts (full).

Note:   Holding tank has only the full adjustment-immerse in water and adjust for 4 volts.

This completes the calibration. Unit is ready for installation.


If you had to cut your sending unit then the EMPTY adjustment must be made prior to installation (see calibration instructions).

Place the gasket on the sending unit.   Align the holes and apply a sealer such as Permatex on the gasket.  Put a small amount of sealant in the mounting holes and insert the mounting screws with flat washers and lock washers.  Place the sending unit in the tank.  Note the holes are not symmetrical, rotate until the holes line up, then tighten down the mounting screws.

It is important that the "Breather Hole" at the top of a fuel probe's tubing be open, to allow the fuel to rise and fall inside the probe.

Centroid Products Centroid

CompuTank Installation and Operating Instructions
Sh. 2 OF 2

Centroid Products, Inc.

2104 HIBISCUS DR.  EDGEWATER, FL 32141        -         TEL : 386-423-3574  FAX : 386-423-3709