The core of FuelPortal is a simple rule: litres that leave a bowser must arrive in a truck. This page explains the instruments on each side of that rule and what happens when the numbers disagree.
The fuel-card transaction or supplier invoice — the claim that litres were bought.
A temperature-compensated level sensor in the storage tank. Temperature compensation matters: diesel expands and contracts, and an uncompensated reading drifts as the tank warms and cools.
A fuel-flow meter on the bowser’s dispensing line, metering every litre that passes through the nozzle. An optional inlet meter does the same for deliveries arriving into the tank.
The vehicle’s own tank-level sensor records the fill; CANbus data (distance, engine hours, consumption) shows what should have been burned afterwards.
Every dispense carries an identity. The driver authorises at the pump by face recognition or an RFID/iButton tag, binding the driver to the truck; a camera records the vehicle at the pump. When a fill event is flagged later, it comes with who, which vehicle, where and when — not just litres.
When the bowser dispenses, FuelPortal expects the same litres to appear in a truck tank in the same window, in the same place. Each fuel event resolves to one of three states:
All measurements agree within tolerance. The event files itself into the fuel records.
The litres disagree beyond tolerance — a short fill, a meter fault, or skimming. Flagged for review with both readings side by side.
A dispense or card transaction with no matching fill on any company vehicle. Paid for; never delivered.
At a commercial filling station the bowser-side instruments are absent, so the slip becomes the claim: the driver photographs it in the FuelPortal app, the litres, price and total are read automatically, and the claim is checked against the vehicle’s measured tank rise — same rule, different source.
Because every litre is measured at every transfer, the records SARS requires for diesel-refund logbooks — litres received into storage, litres dispensed per vehicle per date, and usage — already exist as a by-product. See the diesel refund logbook guide for what the rules require.