Tank Guaging

Henk Stander (Stowe CEO), Shane McArthur (CEO Directech) and Steve Owen (Director Business Development)

In our quest to give our clients access to the best Forecourt peripherals worldwide, we have entered into an agreement with Directech S.A., enabling us to interface to their electronic tank gauging.
The AnyTank Tank Guaging System (Directech) works on the “bubbler” principle, where the resistance to pushing a bubble through a column of fluid is proportional to the weight of the fluid.
This technique makes use of two bubbler tubes, set a precise distance apart. The first measurement that it takes is the differential between the two probes, which gives it the Specific Gravity of the fluid in the tank to 4 decimal places (displayed to 3 decimal places). This is a very important measurement, as it allows us to achieve exceptional accuracy. We have discovered that the acceptable SG of fuels can vary quite widely within the different blends of fuel, and this differential can introduce large errors into the measurement. This is also true of magneto restrictive probes,because their float will sit dfferently in fluids of different SG’s.

This differential pressure is multiplied with the measurement of the lower probe to very accurately compute the weight of fuel and accordingly fuel height in tank and volumetric displacement. The AnyTank gauging has a number of additional advantages that conventional Tank Guaging Systems do not have:
• Their density measurement data can be used to set off alarms when the quality of fuel changes. The system has built in historians for monitoring when these changes take place. Fuel tampering is becoming a major problem in South Africa (i.e. by mixing illuminating paraffin with diesel).
• When vent pipes are blocked, the system measures a “spike” when the tanks are refuelled. As gasses trapped within the vessel create a false density picture, the system is able to convert this signal into a blocked vent alarm.