Fuel is a station's largest asset and the hardest to see: it is underground, changes volume with temperature and leaves through several pumps at once. Controlling its inventory is not an accounting luxury; it is the basis for knowing whether you are earning, losing or giving away product.
Three levels of inventory control
1. Hand calculation. Opening stock plus purchases minus sales. It is cheap, but the result is an assumption: any error in sales, receipts or measurement is hidden inside it.
2. Dipstick measurement. A graduated stick goes into the tank, the level is read and converted to litres with the tank's calibration chart. It is a real measurement, but a one-off: it depends on who takes it, when, and how much gets written down.
3. Automatic probe measurement. A probe inside the tank reports product level, water level and temperature every few seconds, and the system keeps the history. There is nothing to remember, and every reading is stored with date and time.
What to measure in each tank
- Product level and volume, to know how much fuel there is and how much free space remains.
- Water at the bottom. Its presence is an early sign of product quality problems.
- Temperature, because fuel volume changes with it.
- Deliveries. Each tanker discharge should be recorded with time and approximate volume, to check against the supplier's invoice.
- History. A single level says little; a 24-hour, 7-day or 30-day curve shows consumption, deliveries and odd behaviour.
What the regulation says (as of October 2026)
Resolution 40405 of 2020 of the Ministry of Mines and Energy, modified by Resolution 40198 of 2021, is the technical regulation for service stations. According to DIAN's legal compilation it is in force until 30 March 2027 unless the Ministry extends it. Note, as of 29 October 2026: a nullity action against these resolutions is pending before the Council of State (case 11001-03-24-000-2025-00338-00) with a request for provisional suspension; according to the plaintiff trade group's statement, it is still undecided. Check the status before investing. In its recitals the Ministry cites an analysis that discusses requiring inventory consoles and leak detection. The technical annex, which holds the exact requirements and deadlines, was not opened for this article: review it with your technical adviser before making investment decisions.
Separately, the monthly volumetric balance registered in SICOM starts from real stocks and movements; the better your measurement, the easier it is to support. See SICOM for service stations.
How Orbion solves it
The Orbion Tank module measures each tank with a magnetostrictive probe connected to a concentrator. The console shows product, water and temperature per tank, automatically detects deliveries and keeps history; the history can be exported. Probe specifications are in the article on tank gauging. With several stations, you see them all in one console.
Orbion Tank measures fuel; it does not record sales. To compare measurement with sales it is used together with the point-of-sale module (see reconciliation).
Frequently asked questions
How often should I measure my tanks?
With a dipstick, at least when opening and closing each shift. With a probe, measurement is continuous: the system reads it every few seconds, with nobody going out to measure.
Does the probe replace the calibration chart?
No. The probe measures a level; converting it to volume needs each tank's calibration chart. Keeping that chart correct is part of the control.
What is an "inventory console"?
The equipment and software that receive probe readings and show each tank's level, water, temperature and alarms.
Does it tell me if fuel is being stolen?
It shows differences between what leaves the tank and what is recorded as sold. The cause may be an error, a calibration issue or something worse; the system gives you the data to investigate.
Can I start with a single tank?
Yes. You can begin with the highest-turnover tanks and add the rest.
Take the next step
Request an Orbion Tank demo and see your tank inventory in real time.