Kerosene is the brightest and cleanest of the lamp fuels and burns about 50 hours per litre, but it gives off ignitable vapour once it warms to around 38 °C, so it is only suitable for lamps that keep the fuel cool. Diesel works but smokes more, and gasoline must never go into a lamp because its vapour ignites at any ordinary temperature.
Part of Oil Lamp Construction
Kerosene burns brightest and cleanest of the lamp fuels, but it gives off ignitable vapour at far lower temperatures than fat or vegetable oil. Pre-collapse stocks are finite and need careful handling.
Petroleum Fuels Differ By How Easily They Make Vapour
A wick lamp burns vapour at the flame but stores liquid in a reservoir. The danger is vapour forming in the reservoir. The measure is the flash point (the temperature above which a liquid gives off enough vapour to ignite): typical published values are about -43 °C for gasoline, 38 °C or higher for lamp kerosene (the specification minimum) and 52 °C or higher for diesel. These are standard fuel-specification figures, not drawn from other pages here.
- Kerosene — purpose-made lamp fuel. The oil-lamp overview says it burns brightest and cleanest of all options, at about 20 ml/h for a moderate wick.
- Diesel — works, but smokes more. The overview says to use it only in ventilated spaces.
- Gasoline — never. Its flash point is 81 °C below the minimum for kerosene (38 − (−43) = 81), so there is no temperature at which a gasoline lamp is safe.
Why Kerosene Still Needs A Cool Reservoir
Lamp kerosene’s flash point of 38 °C is well above a 20 °C room, but a metal reservoir sits beside a flame, and a metal wick tube conducts heat straight into the fuel. If the fuel warms past its flash point, the air above it becomes ignitable. Practical rules follow:
- Use a lamp built for kerosene, with a vented reservoir, rather than a sealed jar with a flame at a hole in the lid.
- Keep the reservoir clear of the flame’s heat, and avoid long metal wick tubes that carry heat down into the fuel.
- Keep improvised closed-reservoir lamps for fat and vegetable oil, not kerosene.
- Never refill a lamp that is lit or still hot. Fill outdoors if possible and wipe up spills before lighting.
Handling And Storage
- Store kerosene in a labelled, sealed, non-glass container, away from heat and away from children.
- Never use a drink bottle: kerosene swallowed by a child is a poisoning emergency.
- If a salvaged “kerosene” cannot be identified from its container, treat it as gasoline. Do not test it with a flame. See Fuel Siphoning & Storage for recovery and storage of petroleum fuels.
Worked Example
At 20 ml/h, 1,000 ml ÷ 20 ml/h = 50 hours per litre, as the overview states. A pre-collapse stock of 10 litres gives 10 × 50 = 500 lamp-hours, or about 125 evenings of 4 hours.
Safety
Vapour, spills and soot
Kerosene spilled on a hot lamp, a stove or clothing burns fiercely; smother with a lid or dry sand or earth, never water. A kerosene lamp whose flame smokes or turns long and ragged is burning incompletely and making carbon monoxide: lower the wick, trim it and ventilate with an inlet and an outlet. Do not use it to light a room you are sleeping in.
What’s Next
- Learn next: Wick Sizing & Brightness — setting the flame so the fuel burns completely
- Combine with: Glass Chimneys — the draft that cleans up a kerosene flame