Mythbusted!
http://dsc.discovery.com/videos/mythbusters-cell-phone-gas-station-minimyth.html
I’d agree with that. I think the problem is that regular telephones with the hook switches can generate significant arcing that can ignite gas…which you should never use corded phones when there’s a natural gas leak. This apparently was carried over to cell phones which is unfounded.
However there is a slight concern for ignition switch and relay sparking. Unfortunately to turn off and start cars which you have to do at the gas station anyway, so they have to take this into account during design so this also isn’t an issue.
I think the major reasons for shutting off cars is the potential for backfiring, and accidents at the pump for shutting off cars… Plus gabbing on a phone is a potential cause for accidents too…
Yeah. The video I posted wasn’t to the exact episode I saw, they must have done it twice. In the one I first saw they poured gas all over the inside of a tiny shack with many open containers, then left something like 10 phones inside and called them all at the same time. Nothing happened. They ran a wire, a few hundred feet long over to where they were standing and the guy got some static built up from his pants, touched the wire, and the shack exploded.
The only real issue with cell phone is the distraction they cause. If the pump handle fails to click off, they might pump a lot of gas onto the ground before they notice it.
Listening to the radio is no problem if someone else is pumping the gas. Maybe her husband was jealous because she got to listen to Cartalk while he was outside stuck at the pump.
I think the guys were right about leaving the engine on, the biggest danger is if the vehicle somehow gets into gear.
Assuming the rule about shutting off the key at the gas pump makes_sense is already going down the primrose path. Shutting off the key is a ritual -like the stewardess reciting “…for your safety and comfort…” before every airplane flight.
The vast majority have no idea whether shutting off the key still “makes sense”, or even what motivated it in the first place.
The real rule is “don’t tick off the gas station attendant or your passenger”. In reality it has nothing to do with whether or not there’s any realistic risk of fire.
What is a gas station attendant?
You know who refuels without shutting everything down? Big honking jets.
Are we also required to shut off our iPods at gas stations? No? Didn’t think so.
Gas fumes have to be within a limited range of concentration to explode or ignite. Too low a concentration and nothing will happen if there is a spark because there is too little fuel. Too high a concentration and nothing will happen as there is too little oxygen. Just like in a car engine, you don’t want too rich or too lean a mixture or the car won’t run. For gasoline fumes the lower explosive limit, or concentration in the atmosphere, is 1.4% and the upper limit is 7.6%.
Pumping gas out in the open air, you would have to have the spark in just the right location to get ignition or an explosion. Possible, but unlikely. And the odds of the fumes penetrating inside the cell phone and a spark occurring while you are pumping gas, well probably a billion to one. And the shack with gas and cell phones inside probably has too high a concentration.
There’s a greater chance of static electricity spark from getting back in the car while the gas pumps. Before I pump gas I always touch something metal on the gas pump, touch the car, then begin fueling. I never get back in the car.
Well, after pumping, I get back in to leave 
but only after I hang up the hose and get my receipt.
It’s best to take a few easy precautions when pumping gas, since when there is a fire, all hell breaks loose.
But I doubt that using a cell phone would be a concern, unless you are so engrossed in your conversation that you are inattentive to the task.
This is in Hebrew, but you guys can pretty easily figure out what’s going on: http://www.youtube.com/watch?v=x2fI9OU2HWk
They’ve done tests. Despite the best efforts of the testers, they were unable to produce a spark with a cell phone that could ignite gas fumes.
However, they had no trouble in cold dry weather generating a static spark big enough to see and even hurt just by sliding across a car seat in nylon underwear.
So if you want to talk on your phone at the pump, go right ahead.
But take your panties off first.
For safety’s sake.
From my cold, dead hands…
Three things are necessary to initiate combustion:
- fuel
- oxygen
- a heat source of sufficent energy to initiate the process
I think the laws requiring the turning off of engines go back to the not-too-distant past when distributor based systems were common and arcing through tired old insulation was also not uncommon. Today’s cars use COP systems, so those opportunities for arcing to occur are less prevelant, but there are still a lot of old buggys out there.
As regards cell phones, they don’t transmit enough energy to create sufficient heat to start a fire. And I don’t think they can create enough energy to jump much of a gap either (to arc).
I’m surprised no one has mentioned that some lithium ion batteries (commonly used in cell phones) have been known to catch fire under certain conditions (i.e. when the battery and the powered device are defective in some way). However, this danger could exist even if the cell phone is powered off. Certainly the car radio poses no more threat than the dome light, as click and/or clack already mentioned.
According to Motorola research (I’m not associated with them), cell phones don’t cause ignition and in their 2004 study, they found no reported incidents.
I drive a CNG honda, and they do recommend that if you get in to your car while fueling you ground yourself after getting out before handling the gas hose to discharge any static buildup.
@kyrasdad, I’ve heard and read about lithium ion batteries having that issue, but always in a laptop computer, never in a cell phone.
I’m pretty sure (I’ve been wrong before) it has to do with LIon batteris getting wet. They explode when exposed to water. I’m not sure if fuel would have the same effect, but it might.
I don’t know what the thinking was about the cell phone ban, but there is a precedent for worrying about radio frequency emissions in the area of explosives. Radio waves can induce an electrical current in a loop of wire, which is why when explosives are being used, high-powered radio sources (such as radars) are turned off as a safety measure, so that radio waves don’t accidentally set off an electric blasting cap. It used to be that if you were driving on a highway past an area where blasting was being done, you might see a sign that said “Blasting zone. Turn radios off.”
Granted, it does take a fair amount of RF energy to set off a blasting cap, and cell phones and walkie-talkies are such low-powered devices that you still see them used on blasting sites.
But cell phones are such low-powered, sparkless devices that I thought the ban on them while fueling was a dumb idea, back when the ban was first implemented. As I said, I don’t know what the exact thoughts were behind the ban. I only mentioned the RF concern around explosives as a similar issue that may have influenced the thinking of the people who thought up the ban.