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Can Cell Phones Ignite Gasoline Vapors?
Iphtashu Fitz writes "Matthew Erhorn was filling his car with gasoline outside of New Paltz, NY when when he flipped open his cell phone to answer a call. The next thing he knew he was engulfed by a ball of fire. Luckily for Erhorn a quick thinking employee hit the emergency fire suppression system and he ended up with only minor burns. Firefighters investigating the accident concluded that the cell phone triggered the fire. Experts at The Petroluum Equipment Institute disagree however, attributing the fire to static electricity. Since 1992 the PEI has documented 158 cases of gas pump fires believed to have been started by static electricity. Apparently cell phone signals are too weak to ignite gasoline vapors, but the human body can generate enough static electiricy (60,000 volts) from simply sliding out of your car seat to do just that. Do you pay attention to all those signs at the gas pump telling you to to make sure your car, cell phone, PDA, pacemaker, etc. are all turned off before you start pumping?"
no more self-service stations for me.
The stats also show that women are "the cause" of more fires at the gas pump. Hey, don't blame me... it's just the stats, ma'am!
The Mythbusters took care of this MYTH in episode #2:
Episode 2: Cell Phone Destruction, Silicone Breasts, CD-ROM Shattering
In this episode, Jamie and Adam test several explosive theories. Can chatting on a cell phone while pumping gas cause the pump to blow up? Our mythbusters put themselves at risk so you don't have to. They also put silicone breast implants to the test at high altitude. Will they burst under pressure? Finally, we'll learn once and for all if high-speed CD-ROM players can really shatter a compact disc.
"I'm not ashamed I can't function in society like I'm supposed to." - Paul Westerberg
They're flammable and they originate mere inches from our cell phones.
"...all the labours of the ages, all the devotion, all the inspiration, all the noonday brightness..." yada yada
The warnings about not using your cellphone at a gas station is because you might drop it and the battery pack might come loose. This could spark as well and cause a not-so-static discharge.
They did a thing about this on Mythbusters on Discovery, and were unable to start a fire this way. They pretty much concluded that the static you build up from getting in or our of the car during a fill-up can cause a spark if you touch the car. And doing that near the fueling point can cause a fire. Of course, the worst thing you can do then, which most people do, is pull the hose out of the tank and proceed to spill a LOT of gas into an already burning fire. Not good, especially when you are the one removing the hose. Leave the handle and hose right where it is and get the hell out of there.
And here is a little more data on this urban myth.
WWJD?
JWRTFM!
Moving on from the gas station thing, what are people's policies about cellphones (or mobiles as we call them in the UK!) and computers. I'm currently in my computer science lab and if I get my phone out of my pocket I'll be banned for the day.
Are they being overly paranoid? Can cellphones really disrupt your average PC in as much as they might ignite petrol fumes...
If the phone is on fire.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
You are not telling the story in hope that people follow the link.
Here it goes, short version: they tried, they tried hard, to make a cell phone ignite gasoline vapours... and they failed miserably. They put the stuff in a closed environment, tested many concentrations of gas vapour, nothing worked.
The only way this happens is static electicity near the fuel entrance
It's better to be the foot on the boot than the face on the pavement. ~~ tkx Kadin2048
A rather trashy science program in the UK on Sky, called Braniac: Science Abuse performed an experiment where they covered a trailer in gasoline and left a mobile phone in it. They then phoned it. Nothing happened. Then they added more gas and mobile phones, and phoned them all at the same time. Still nothing happened.
Not sure it proved anything, so they blew it up with something anyway. Bit of detail here.
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In the UK they cell phone transmitters on petrol stations.*
Hey, it's the gasoline that causes the burns not the cellphone. :-)
We are blaming the wrong item here
Time to get rid of this way to old fashioned source of energy anyway.
if your pants fit well, it's not only because of the pants
Turn off you PACEMAKER? What?
They did manage to get a very nice explosion by leading a wire to the cravan and getting soomeone wearing nylon clothes and standing on a bucket to touch the other end, though.
PS. They really liked blowing up caravans...
Further coverage of this myth here.
Sono koro, bokura wa, sore ga sekai no shinjitsu da to shinjite ita.
Is that the fire chief is so adamant about blaming cell phones rather than simple static electricity.
1. Cell phones emit minimum amount of power (no microwave heating of the fumes).
2. AFAIK there's no documented cases of cell phones starting a gasoline fire.
3. Electric sparks obviously can start gasoline fumes on fire. How do you think a spark plug works?
4. We all know how easily static electricity can build up from simply walking across a rug on a dry day.
Kinda makes you wonder just how much training the fire chiefs have. I'm sure they know how to fight fires, but at least this guy seems to have limited knowledge and analytical skills about how fires start.
AccountKiller
It seems as if, reading the report, that nearly all of these accidents resulted from someone putting the nozzle into the vehicle, then locking it on, leaving, coming back, and a static discharge igniting the vapours near the filler cap.
This is reasonable - you quite often feel small static shocks. Especially in dry hot weather, perhaps explaining a high incidence of acccidents in Texas and Nebraska, and a lot less in humid coastal ares.
And when you are filling up, you often see clouds of vapour almost pouring out of the filler. These would be very easy to ignite.
Here in the UK you can't put a pump on automatic fill. You need to hold the trigger whilst all the time. The handle is grounded, so that as soon as you touch it, the static goes, and as long as you keep on holding it, there won't be a problem, as there will be no sparks.
I have a video on my email, girl gets out of car, starts pumping her gas, gets back in her car to what looks like put some lip stuff on. she gets back out and goes to touch the handle pumping gas into her car, and whooosh! fireball.
she pulls the nozzle out of the car, and you can see fire comming from the gas tank, as well as the nozzle. she ends up dropping it and running away.
all from a little static..
With process plants if we got any level of escaped gas etc.. you initate a level 1 shutdown which kills power to everything.
Even the UPS sytem that fed an automated tranmitter, the idea being that the transmitted radio waves could induce current and possibly lead to a spark in any nearby metal.
Petrol isn't quite as flammable, but the same principle applies. If you had you phone near a suitable surface an incoming call may well have the same effect.
Personally i'm more concerned about the mobile phone masts they have installed in petrol station signs.
There are things we know we don't know and things we don't know we don't know. - Donald Rumsfeld
On the Discovery Channel there is a show called Mythbusters (love that show) and they tried every which way to see how a cell phone can ignite gasoline vapors.
They had there "blast chamber" filled with gas vapors and oxygen. Called the cell phone and nothing happened. Infact they ended up trying just static electricity and still nothing happened.
I work for a major manufacturer of gasoline dispensers (and many run Linux).
The sigificant risk for ignition via a cell phone is by dropping the phone. The battery separates, and a spark insues.
UL defines the Class I Division 1 area (considered explosive) as approximately 3 feet high and 18 feet in diameter from the source (dispenser). At the typical operational height of a cell phone there is little risk, even if there was sufficient RF energy. However if you drop it, the vapor does hover above the ground and presents a significant risk.
The predominate risk is static electricity. In times past (the 90's and earlier), vehicles would simply vent the vapor (largely pentane and butane) from the tank's fillneck by displacement as fuel was introduced. This led to a cloud of saturated vapor in proximity to the fillneck that was too rich to ignite at the fillneck interface. Newer vehicles have onboard vapor recovery whereby a carbon canister retains the vapor as your dispense. Consequently saturated vapor no longer clouds the fillneck area and the explosive region moves closer to the fillneck where a spark from static dischage (nozzle to car/hand to nozzle/hand to car) will cause ignition.
Treat fueling like handling a chip. Discharge yourself against the pump chasis first (damn well grounded) and vechile to put everything at the same potential before dispensing.
NEVER refuel a portable gasoline container upon an insulated surface like a carpeted trunk or plastic truck bedliner. Set it on the concrete, otherwise you've crated a perfect Lynden Jar capacitor. Many fires happen in this manner.
You're not going to get high voltage out of a piezo transducer which is being driven from a 4.5 volt battery through a low-impedance path. And if you could get high voltage by dropping it, lots of people would have blown electronics from dropping their phones; you might notice that this does not happen.
Time is Nature's way of keeping everything from happening at once... the bitch.
between fire and explosion with Gasoline... that might help delineate what we're talking about here.
For a cell-phone held in the hand, we're probably most worried about igniting gasoline vapors, leading to a subsequent fire (unless you're bathing your cell phone in liquid gasoline while talking on it. Nobody's doing that, are they? Please tell me no...)
Gasoline has a flash point about 40-50 degrees below zero, so unless you're in the arctic circle somewhere, gasoline will almost always be producing some vapors. Those vapors can be ignitable and explosive... but only within a certain range of concentration. The range is between the LEL (Lower Explosive Limit) and the UEL (Upper Explosive Limit)... This naturally varies by compound... but for standard gasoline is roughly 1.5% and 7.5%, respectively.
I've never studied it personally, but I'd think the odds of getting just the right concentration around your cell phone (multiple feet from the nozzle) such that it leads to an explosion and fire are extremely small.
Static electricity? Now that's a much more likely culprit... there have been multiple cases where that's happened.
Even if a man chops off your hand with a sword, you still have two nice, sharp bones to stick in his eyes.
The stats also show that women are "the cause" of more fires at the gas pump. Hey, don't blame me... it's just the stats, ma'am!
Nylon rubbing against cotton in a dry environment is a midget lightning storm, quite suitable for igniting gasoline vapor (or any other explosive vapor mixture). Women wear full-leg nylon stockings or pantyhose under loose cotton dresses MUCH more often than men. B-)
[...] Mythbusters [...] episode #2: [...]Can chatting on a cell phone while pumping gas cause the pump to blow up?
First you need an explosive mixture. With gasoline that's a rather strong concentration in air - present in a narrow region JUST OUTSIDE the gas pipe when filling without a vapor revovery system.
The you need a spark IN the explosive mixture. The spark can be VERY tiny. But it must be surrounded by the correct mixture, with a trail of the mixture back to the cloud of vapor emerging from the filler neck, through an open path large enough to propagate the flame without stealing its heat and quenching it (as passage through a metal screen with suficiently narrow holes will do).
Such sparks can occur on the breaking (and sometimes making) of any electrical contact inside the phone. But phones are pretty well sealed - especially the flexible circuit contacts under the buttons. (I'd be more concerned with the switch detecting the cover of a flip-phone.) You'd probably need a phone with a defect in the case - as well as holding the phone near the filler neck while filling for several seconds - to ignite gas fumes that way.
Another potential is arcing at the tip of the antenna (where the voltage is enormous) or the tip of a nearby object like a sheet-metal screw. (Even a near-invisible brush discharge would do the job.) Such screw tips are normally not found in the region around the filler neck where an explosive mixture is likely (both because they'd tend to savage the hands and clothing of people trying to fill the tank AND because they encourage static discharges, so the designers very carefully keep them away from the filler.) The tip of the antenna on a cellphone is normally imbedded in rubber, so no arc there unless there's a defect (like a pinhole) in the rubber. Also: Except for the old AMPS-system phones the cellphone signal is a rather broad spread-spectrum. This reduces its ability to excite a resonance in nearby metal leading to a high-voltage at the end of a conductor (like a screw point).
Note, however, that a cellphone doesn't have to be switched by the user to transmit. It sends a short burst every few minutes when it "checks in" with the local cell sites. An incoming call turns its transmitter on, increasing the opportunities to get any arcs it's producing into the explosive region as the user moves it around.
Third: If the battery came off you'll get a spark at its terminals as it disconnects. Again the caveat about getting an explosive mixture to the area of the spark with a path back to the vapor cloud.
Jamie and Adam "testing several explosive theories" on one segment of a show are hardly an exhaustive disproof. How many of the hundredish models of phone did they test? Did they arrange for a controlled concentration of gasoline at the phone, neither too rich or too lean, so it would actually ignite? Did they crack the phone cases in various ways to create an ignition path? Did they carefully make a pinhole in the rubber duckie antenna right at the end of the conductor?
Just like being hit by lightning or meteorites, gnition of vapors during fueling, from ANY source (even lit cigarettes!), is a rare event that nevertheless occurs when the conditions are JUST right. And getting the conditions right is hard - in part because automobile designers try to reduce its likelyhood. Millions of fillups occur daily, yet ignition is very rare. No offense to Jamie and Adam, but a few attempts to get it to occur while taping one segment of a show would be extremely unlikely to result in a fireball, e
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Actually, you can start a fire with the end of a cigar/cigarrete. The difference is vapors. A large gas spill on a non-porous surface causes a vapor build up near the ground very rapidly. The cigar enters the vapor field and ignites before it hits the main pool of liquid. If the vapors weren't present the cigar would just drop into the pool and go out, just like in your experiment.
is the voltage on the antenna really enormous?
Absolutely.
An antenna is a transmission line terminated with an open circuit. (This IS a striaght-line - or bent in various ways - transformer.) The voltage at the end is quite high. If it's excited at its resonance, it is limited only by the losses from radiation, resistance, and surrounding materials.
Consider the "firefly" decorations once popular on CB antennas. 4.5 watts into 52 ohms produces 15 1/4 volts. A neon lamp requires about 90 volts to ionize and I think it's about 45 to sustain. Yet put one on the end of the antenna and it lights up merrily when you key the transmitter. No big illegal power amplifier required.
Repeat after me: 3 volts do not arc.
Sure it does, under a number of conditions.
You're thinking of STARTING an arc in air. For three volts the gap would have to be microscopic.
But when breaking a circuit with current flowing through it you end up with exactly that microscopic gap initially. Once the air is ionized the arc can be sustained by a very low voltage. And with any inductance in the circuit at all (even the stray inductance from the wiring) the voltage will climb to maintain the arc until the current through the inductor is finally brought to a halt by the reverse voltage. So the arc can be "pulled out" to significant lengths.
This is EXACTLY the mechanism that produces the voltage spike in the primary (and thus also in the secondary) of the transformer in a contact-point type auto ignition.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Yes.. I leave it turned on. No, it has never rung while doing so...
~m
"Yes, I have a Disaster Recovery Plan. It's called my Resume"