Kerosene/parafin set alight by static electricity?

[bluedolphin]

A friend of mine spilt a jerry can full of kerosene/parafin in the boot of his car on the way home from the petrol station. I thought it would be very dangerous to clean up, but he said it wasn't and went ahead and soaked it all up with blankets. Was I right ? Could it have ingnited in his trunk as he was cleaning up from static electricity or from sparks from the cars electrics (rear lights)????

[darth vader]

ignition from the car electrics - no (if the keys are removed therefore no power to the lights etc.). Ignition from static electricity - no, this is a different kind of electricity to the flowing electrons type you get in wires (otherwise people would spontaneously combust everytime they filled up their car etc). Also paraffin and kerosene have low boiling points and tend to evaporate quite quickly. So all this said i think your friend was pretty much ok as long as he wasn't smoking a cigarette or near a naked flame or anything.

[KARL]

Attitudes vary greatly as to what is dangerous. Large companies, particularly multinationals, and US connected companies most of all, tend to go to great lengths to identify "hazards" and take measures to protect against them. The associated philosophy is spreading rapidly in this country. An example which most people will be familiar with is seeing construction workers on a road job going around with hard hats. All their work, equipment, etc. may be at or below eye level but they are required to and accept wearing hard hats for "safety" reasons. What this practice adds to their safety I do not know, and I often wonder whether the same people wear the things to bed for safety reasons, even though they are stupendously uncomfortable for any legth of time. Paraffin/kerosene (for all intents and purposes the same fuel, US terminology does not include the word "paraffin") is quite a lot less inflammable than petrol/gasolene but more inflammable than diesel oil (called the flash point, a particular temperature in each case). Either of the first two types will create a buildup of fumes in a closed container (incl a boot) at normal ambient temperatures and petrol fumes would be quite dangerous. You can actually put out a match by sticking it into diesel fuel though and nothing will be set alight. Not being an expert, I cannot say how easily paraffin fumes would ignite when a spark is introduced, but a Hollywood style explosion seems to me highly unlikely in UK temperatures at this time of year. On the other hand, in the closed boot of a a dark coloured car parked in sunshine on the hottest UK summer's day might be another matter (I would not like to put it to the test). However, apparently paraffin or white spirit (aromatics, so called) soaked rags (and presumably blankets also) can spontaneously combust if left lying - without a spark or naked flame of any kind being involved (again, I accept the warnings one frequently comes across).

[Hamish]

Darth vader, Ignition from static is as real a danger as from electrical contacts. The differance is there is much more likely to be a spark with a switch / porr contacts etc than with static. The flamability of a material does not depend on its boiling point. Dichloromethane boils at 40C and is non-flamable, ether boils at about 32C and is extreemly flamable, infact ether can be ignited by a spark at temperatures as low as -40C. It is the flash point and the vaopur dencity which are important. The flash point is the temperature at which a flamable liquid with ignite by a spark. If the vapours of a liquid are dence then they will collect and it is possible that the ratio of vapour to oxygen will result in an explosive mixture.

to answer bluedolphins question, as you can see from above, it would depend on the flash point of the fuel and the precoutions taken. It would perhapse have been more of a risk that your friend could have eben over come by the fumes and passed out.

[darth vader]

I'm sorry but i have to disagree - to ignite anything by electro-static charge, you would have to create a spark which would essentially mean standing there with a van der Graaf in your hand. If it was a real problem then there would be precautions at Petrol stations. The fact that you're standing there behind the car means a) your earthed to the floor and b) your naturally dissipating static-electricity in the air so i would definitely rule out static-electricity as a possible cause of ignition

[sft42]

And have you never got a shock as you touched a car door Lord Vader? As a one time "responsible person" for esso i was trained to take in fuel deliveries and i can tell you we got to see some really scary videos of people doing stupid stuff.....Mostly your friend was just being average it would take some bad luck for a strong enough charge to build up to cause a large enough spark to ignite the fumes that would build up in the boot (the actual liquids not being volatile as previously discussed) but it's not a practice i'd recommend to anyone who doesn't fancy seeing the inside of a hospital burns unit at some point.

[gazzawazza]

Just to clarify some points, the "heavier" a fuel is then the slower it evaporates and the more difficult it is to ignite. This is because it is not the fuel (ie the liquid) that burns but the vapours evaporating from it and explains why diesel is relatively "safe," it is a heavy fuel and normally needs a wick to ignite it. Petrol, on the other hand is a very "light" fuel which evaporates easily. This is why it is so highly flammable and used in vehicles, and anywhere petrol is used is a potential "flashpoint" (not a pun). This is why it's so dangerous to use mobile phones or any battery operated equipment in a petrol station. Even receiving a call on a mobile can provide the spark to ignite vapours which are in the right mixture, and wherever there is petrol (either a spill or being put into fueltanks of vehicles) then there will be vapours in the right mixture to cause ignition.

I cringe whenever I see people getting in their car and lighting a fag, it's obvious some people just do not realise how dangerous this is.

[darth vader]

true sft42, but the charge built up whilst i was in the car, and dissipated (via my finger) into the car's frame when i got out. By the time i'd walked round the back of the car i must have dissipated most (if not all) the static that may have built up on my body.
Darth Vader, pedants anon.

[Eddiecurrent]

Mr Vader Whether you like it or not your point of static electricity being different to the stuff in wires is wrong. A spark of static electricity is merely a build up of electrical energy that has no continuous source (i.e. no battery or generator) it does contain enough energy to ignite fuel, that is why aircraft refuelling trucks have a large earth strap to conduct to ground any static build up, the two metal strips rising from the tarmac at F1 pitstops have the same function.