Petrol and static electricity don’t mix. Here’s how to keep them apart
Static electricity is the commonest cause of service station fires. This is not because motorists are closet pyromaniacs - it's because many are unwittingly stupid. Most of us underestimate the wickedly destructive potential flowing from the massive amounts of energy locked into conventional liquid fuels - and how ready to 'go off' they are. We also don't join the comparatively easy dots comprising the relationship between static electricity, fuel and explosion.
There are more fuel safety tips here.
Whenever the mercury luxuriates on the warm side of minus 43 degrees C, which is mostly, petrol evaporates spontaneously to form an explosive vapour mix in air. In this condition, a spark is all you need to even up your chances of making the lead story on the 5-O’clock news.
It's that simple: petrol vapour plus spark = explosion. If 'Molotov' isn't your middle name, best not get involved here.
This is why most of us comply with the arm-long list of bowser prohibitions. Not smoking, ignition off, etc. Mobile phones, portable two-way radios and other battery-powered electronic gizmos are banned because if you drop one you might dislodge the battery, invoking a tiny spark. This danger is grossly over-stated, and community perception of it is high. Most of us, however, underestimate a far greater risk.
The great, unsung potential ignition source at a servo is static electricity. You don't really need a mobile telephone, a lit ciggie, etc. According to the American Petroleum Institute, the risk of a static-catalyzed explosion at the bowser is tangible, albeit low. It blows people up every year. (This is because, despite the low risk, the vast quantities of petrol being handled in the community mean events like these will happen - with extreme consequences to those involved.
If you take some simple precautions, however, they don't have to happen to you.
You can minimise your chances of scoring a static electricity ‘own goal’ at the bowser by always touching a metal part of the car away from the filler neck after getting out but before handling the pump. This grounds you to the vehicle, away from concentrations of fuel vapour.
This is the best way to discharge any static charge you might have built up in the car. The worst conceivable way is to discharge your charge via the fuel pump nozzle...
If you’re in the boonies, you might come face-to-bowser with one of those nozzles that locks on, allowing you to attend more pressing matters as the fuel flows. Do not re-enter the vehicle. That Lycra jumpsuit you’re wearing could scrape across your silk seat covers, creating a static buildup faster than you can say ‘bad taste; I grew up in the 1980s’. (All dissimilar fabrics will generate a charge.) You might otherwise re-emerge from the vehicle, grab the pump ... and wake up in the burns unit.
More risky than re-filling the tank is the Saturday morning pilgrimage for mower fuel. Never re-fill any portable fuel container inside the vehicle (say, in the boot), or in the tray of a ute, in the bed of a trailer or strapped or otherwise mounted to the vehicle (as on many 4WDs). Static can jump between the pump nozzle and the container.
The Americam Petroleum Institute says 80 per cent of static electricity fires involving portable containers are caused by re-filling them in the plastic-lined tray of a ute. Plastic tray liners insulate the container from the vehicle, allowing a substantial charge to exist at the container, even if you ground yourself on the vehicle by touching it.
Instead, place any portable fuel container on the servo’s concrete apron, and rest the nozzle on it during the fill so that it is in electrical contact with the can.
Last nasty twist concerning static electricity and fuel? Fuel generates its own static electricity as it flows down the pump’s rubber hose - just ask any fuel tanker driver. Step one of their de-canting process is always ‘attach earth strap’. So, when you’re filling a portable container, manually throttle back the flow rate. This will minimise any charge building up, and also reduce minor spills, which contribute to explosively charging the atmosphere where you’re working.