A filling-station underground tank holds 10,000-40,000 litres, a farm bulk tank 1,000-5,000 litres and a home heating-oil tank about 1,040 litres, and each needs a hand pump with a long hose rather than a siphon. Open buried fill ports slowly with brass, aluminium or plastic tools, stand upwind, keep your face away from the opening and bring no flame or spark-capable light near it, because the space inside is full of fuel vapour.
Part of Fuel Siphoning & Storage
Fixed tanks are where the quantity is, and where one mistake costs most, because a buried tank concentrates vapour and a large above-ground tank concentrates fuel.
Fixed Tanks Are Safest When You Treat Them As Vapour Chambers
Filling-station tanks. The parent article gives 10,000-40,000 litres per tank and 2-6 tanks per station. Without electric dispensers, extraction means a manual pump and a hose long enough to reach the tank, 3-4 metres below ground. The fill ports are usually metal caps in the ground near the pumps. Different tanks at one station hold different fuels, so the grade markings on the caps and pumps are the first thing to read.
Farm bulk tanks. Above-ground diesel tanks of 1,000-5,000 litres, often with a gravity outlet or a hand-cranked pump. Fuel dyed red is the tax-exempt diesel; the parent article treats it as otherwise equivalent to road diesel.
Home heating-oil tanks. The common size in the parent article is 275 US gallons, kept in a basement or beside the house. Heating oil is essentially diesel. It ignites less readily than gasoline, but a spilled basement is still a fire and slip hazard.
Standby-generator tanks. Commercial buildings, hospitals and cell towers have diesel tanks of 500-10,000 litres, often inside locked enclosures.
What You Need
- Manual rotary or lever pump with a long drop hose for the 3-4 m depth, see Pump Siphon & Transfer Pumps.
- Non-sparking tools, brass, aluminium or plastic, for opening the fill caps.
- Metal or approved containers and the transfer room to hold them; see Approved vs. Improvised Containers.
- A second person standing clear and upwind.
Method: Open Slowly, Pump From A Distance
Step 1: Read before you open. Identify the fuel from the signage on caps and dispensers. If the markings are gone, treat the contents as gasoline until proven otherwise.
Step 2: Clear the ignition sources. Nothing burning, running or switching within the work area. No steel hammers on a steel cap.
Step 3: Open the cap slowly. Stand upwind with your head well to one side and your arms extended. Pressure or vapour may escape. Wait for it to stop. Leave the cap off for a time to let the vapour disperse before you lower the hose.
Step 4: Lower the hose, do not drop it. Let a plastic or rubber hose feed in by its own weight until it touches bottom, then raise it a few centimetres. Do not let a metal pump fitting scrape on the riser pipe.
Step 5: Pump into containers placed on the ground, with each nozzle touching the container rim, and stop short of the bottom, where water and sludge lie. Tanks that have sat for a long time collect water at the bottom.
Step 6: Close the port, put the cap back and record what was taken from which tank.
Worked Example
A 275 US gallon heating-oil tank holds 275 × 3.785 = 1,041 litres when full, which agrees with the parent article’s 1,040 litres. At one 20-litre jerry can per trip, that is 1,040 ÷ 20 = 52 cans. Plan the storage for the full count before you start pumping.
Common Mistakes
- Opening the cap, lowering a hose and walking away. A buried tank is not a bucket. Vapour escapes continuously and a person leaning in can be overcome.
- Drawing the tank to the bottom. The remaining litres hold water and sludge. Leave them.
- Mixing fuels from different tanks in one container. You cannot unmix them.
Safety
Buried tanks are vapour chambers
The space above fuel in a buried gasoline tank holds vapour that is heavier than air and ignitable by a spark from a steel tool, a switch or a static discharge. Use only brass, aluminium or plastic tools near the fill port, with no flashlight with an exposed switch, and no flame of any kind. Never lean over an open port or put your head into it, and never climb in. Never use a flame to test whether vapour is present; assume that it is. Never fill a plastic container on a vehicle seat or carpet.
What’s Next
- Learn next: Pump Siphon & Transfer Pumps — the hand pumps that suit deep tanks
- Combine with: Storage & Safety — storing hundreds of litres once you have them