Before decanting — the only time you have leverage
Once fuel is in your tank it is mixed with what was already there, and every question about what arrived becomes an argument about inference rather than a matter of measurement. Everything below happens with the tanker still sealed or still loaded.
- Check the seals against the numbers on the invoice, compartment by compartment. A broken or mismatched seal is a stop, not a note. The free tanker delivery log has a row for every check below, so nothing is remembered rather than recorded.
- Dip your own tank and record it. Without a pre-delivery dip there is no baseline, and the post-delivery figure proves nothing.
- Take a density and temperature reading from the compartment sample. Record both — a density without its temperature cannot be corrected by anyone afterwards, including you.
- Correct the observed density to 15 °C — the density and temperature calculator does it — and compare against the invoiced figure. A material difference is a product-quality question, and it is answerable now.
- Check the compartment dip against the invoiced quantity for that compartment.
Warm fuel is not extra fuel
Fuel gauged at 38 °C on the forecourt occupies more space than the same fuel once it has cooled to underground temperature. The difference is real litres in your tank and a real loss in your register, and it is the reason a summer delivery so often looks like a shortage a few days later. Correct to 15 °C before comparing anything.
During
Decantation is the part with the safety consequences, and the part where the fewest useful measurements are possible. Keep it uneventful.
- No dispensing from the receiving tank while it is being filled. A nozzle drawing during decantation makes the arithmetic unrecoverable.
- Watch the compartment empty completely. Fuel left in a compartment is fuel you paid for and did not receive.
- Keep the delivery attributable to one tank. Splitting a compartment across two tanks without recording the split makes both stock registers guesswork.
After — and the claim window
Let the tank settle before dipping. Fuel that is still moving reads high, and a dip taken immediately after decanting will overstate what you received — which then turns into an unexplained loss over the following days as the reading corrects itself.
Once settled, the arithmetic is simple: post-delivery dip minus pre-delivery dip is what actually entered the tank. Compare it against the invoiced quantity corrected to 15 °C.
If there is a shortage, work out how much of it is real and raise it immediately and in writing. Every supply agreement has a window, and the practical window is shorter still — a claim made the same day rests on measurements; a claim made next week rests on your word.
| Compare | Against | A gap means |
|---|---|---|
| Invoiced quantity | Compartment dip before unloading | Loaded short, or a gauging difference at the terminal |
| Compartment dip | Your tank's dip difference | Fuel left in the compartment, or a spill |
| Invoiced quantity at 15 °C | Your tank gain at 15 °C | The real shortage, once temperature is out of the way |
The three quantities that must agree, and what a gap between each pair means.
What to record, permanently
A delivery that is not recorded in enough detail cannot be reconstructed, and the day you need to reconstruct one is the day it went wrong.
- Invoice number, company and date.
- Litres invoiced, per compartment and per tank.
- Observed density and temperature, and the corrected density at 15 °C.
- Pre-delivery dip and post-settlement dip, per tank.
- The tank each compartment went into.
- Any seal discrepancy, in writing, at the time.
Frequently asked questions
How long should I wait before dipping after a delivery?
Long enough for the fuel to stop moving and for entrained air to release — in practice a matter of minutes rather than seconds, and longer for a large drop into a nearly empty tank. A dip taken too early reads high and manufactures a shortage over the following days as the number corrects itself.
The invoice quantity and my dip differ by a few hundred litres. Is that a shortage?
Not necessarily, and temperature is the first thing to rule out. Correct both to 15 °C before concluding anything — the tanker shortage calculator does exactly that and separates the part that is genuinely missing from the part that is only temperature. A difference that survives the correction is worth raising the same day; one that disappears under it was never a shortage.
Can I refuse a delivery?
A broken or mismatched seal, or a density materially away from the invoiced figure, are grounds to stop and escalate rather than decant. Once the fuel is in your tank, both questions become unanswerable — that is precisely why the checks come first.