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?"

Comments

Urban Myth!

[musicscene]

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.

Re:Urban Myth!

[LocoMan]

The reason cell phones aren't allowed on airplanes also have to do with the way the cell phone networks work. They were designes to have a cell phone in range of mostly 3 or 4 cell phone transmitters (no idea what their real name in english is) at the same time, then they decide which one is the strongest and communicate you trough it. When you're airborne, the cell phone signal can be in range of hundreds of transmitters at the same time, clogging the whole service and making it reject lots of land-based calls. Which is probably why some airlines now allow you to use the cell phone, but only after landing. Or at least that's what the Iberia magazine said last time I went to Spain.

NO!

[hummassa]

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 can't be that likely...

[gadders]

In the UK they cell phone transmitters on petrol stations.*

Re:is the voltage on the antenna really enormous?

[Ungrounded Lightning]

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.