News of another fire tragedy hit the headlines last week when a man died after being engulfed by flames when “priming” a bonfire with petrol. Some may view using petrol as an accelerant as reckless but my guess is that many people have done exactly the same without fully understanding the dangers.
Petrol evaporates quickly when exposed to air which is why petrol and other flammable fuels and chemicals should always be stored in an air tight container. We all know that petrol is highly flammable but just how flammable is revealed by its flashpoint. The flash point is an indication of how easy a chemical may burn. Materials with higher flash points are less flammable or hazardous than chemicals with lower flash points. Petrol has a flashpoint of -45 Degrees Centigrade – the minus sign is not a mistake – so petrol will basically ignite at any temperature found in the UK.
What is less understood is the auto ignition temperature i.e. the minimum temperature required to ignite a flammable gas or vapour in air without a spark or flame being present. For petrol the figure is around 280 Degrees Centigrade which is far less than the temperature of a naked flame.
When you pour petrol on a bonfire the fuel begins to evaporate. As a rule if you can smell it you are effectively stood in an invisible cloud of potentially flammable gas. The molecules in the gas are also invasive and will stick to clothing turning you into a tinder box. Once the concentration of gas in the air reaches a certain level termed the flammable range lighting a match or introducing other sources of heat will cause an explosion.
For this reason flammable liquids should always be stored in an enclosed air tight container in a purpose made COSHH Cabinets to prevent the build-up of explosive gases and protect the contents from accidental exposure to sources of heat.
Never use any flammable fuel to start a fire not even diesel or oil. Firelighters work out a good deal cheaper than car fuel and are very effective and most importantly safe.