Pickup truck fueled by compressed natural gas explodes at gas station

Plot Device

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I realize that gasoline is explosive. But my understanding about CNG is that it's ...... more explosive (or at least more easilly ignited).

http://www.youtube.com/watch?v=ChCVfn9ePDc

http://ktla.com/2013/01/24/mans-car-explodes-at-gas-station/

30 seconds long, safe for work.

(KTLA Channel 5, Los Angeles)





And here's a nifty factoid: AT&T's nationwide fleet of 5,200 service vans are all now officially CNG-powered.

http://dfw.cbslocal.com/video/7854774-att-service-vans-running-on-natural-gas/

2 minutes long, safe for work.

(CBS-affilliate, DFW Channel 11, Dallas-Fort Worth)
 

Torgo

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This looks like an appropriate opportunity to use the lovely word 'stoichiometric'.
 

PorterStarrByrd

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I wonder if there are more or less explosions per operating hour with CNG than with Gasoline. There is heavy usage of the former in fork lifts etc without a large number of reported incidents (by media).
It is easier to ignite than gasoline but both both systems are pretty safe with proper vehicle maintenance.
 
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Ambrosia

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Watching the video it is apparent the man knew there was a problem because he moved quickly to remove the hose from the truck but didn't manage to stop the explosion. I wonder what it was that caused the explosion--besides the natural gas, of course.
 

Plot Device

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Watching the video it is apparent the man knew there was a problem because he moved quickly to remove the hose from the truck but didn't manage to stop the explosion. I wonder what it was that caused the explosion--besides the natural gas, of course.


I saw that also. I watched a couple times in a row to see if I could spot what it was that sent him into such a 5-alarm state during those 3 seconds PRIOR TO the explosion. I couldn't suss it out. But I am curious.
 

clintl

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I saw that also. I watched a couple times in a row to see if I could spot what it was that sent him into such a 5-alarm state during those 3 seconds PRIOR TO the explosion. I couldn't suss it out. But I am curious.

I think I can guess what probably happened. Notice that the explosion happens when he touches the nozzle, and that he's moving toward it the nozzle, not away from it. I bet what happened is that he noticed some leakage from the nozzle, reached for it to shut it off, and when he touched the nozzle, there was an electrostatic discharge from his body to the nozzle, igniting the CNG. It can happen with gasoline, too - there's a Mythbusters video about it that I show to my chemistry students every year.
 

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I think I can guess what probably happened. Notice that the explosion happens when he touches the nozzle, and that he's moving toward it the nozzle, not away from it. I bet what happened is that he noticed some leakage from the nozzle, reached for it to shut it off, and when he touched the nozzle, there was an electrostatic discharge from his body to the nozzle, igniting the CNG. It can happen with gasoline, too - there's a Mythbusters video about it that I show to my chemistry students every year.

That was what I thought, too - saw the same episode the other day! The other thing that occurred to me was that maybe the pressure vessel just failed. I don't see much of a fireball, and the blast seems to happen mainly under the bonnet. Maybe he heard a rivet pop or something?
 

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I'm thinking static electricity, too. Looks like the explosion happened at the time his hands touched the truck and the fuel pump, as if he completed some circuit.

Regular gas fuel pumps have warnings about static electricity, that you shouldn't get back into your car while fueling and then get out again to finish. That just builds up a charge that is released when you touch the nozzle.
 

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That's one of the big worries with lots of alternative fuels. Gasoline is stable enough that untrained people can handle it (usually) without incident. Compressed natural gas and hydrogen are more volatile. Perhaps the alternative fuel pumps of the future will have a trained person dispensing it, like in the old days.

I bet he heard a hiss or smelt gas, and thus learned there was a leak. His first impulse was to go to where the leak was rather than shutting it down at the source.
 

frimble3

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That's one of the big worries with lots of alternative fuels. Gasoline is stable enough that untrained people can handle it (usually) without incident. Compressed natural gas and hydrogen are more volatile. Perhaps the alternative fuel pumps of the future will have a trained person dispensing it, like in the old days.

Good point about the pump attendants. They got rid of them to save money, because they weren't a necessity, but if they're a safety system, bring 'em back.
 

clintl

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Good point about the pump attendants. They got rid of them to save money, because they weren't a necessity, but if they're a safety system, bring 'em back.

You're saying everyone should have to live like an Oregonian?
 

blacbird

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I realize that gasoline is explosive. But my understanding about CNG is that it's ...... more explosive (or at least more easilly ignited).

As a liquid, gasoline is not explosive. Gasoline vapor is, however, at the right concentration with oxygen. Same is true for methane (natural gas) and hydrogen. The difference with methane and hydrogen is that it is normally stored as pressurized gases, as are such familiar fuels as propane and butane. Uncontrolled release of that pressurized gas can quickly lead to explosive conditions, and any little spark, like static electricity, can set it off.

caw
 

robeiae

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On the exploding car front: http://myfox8.com/2013/01/29/mass-womans-car-explodes-after-she-uses-remote-to-unlock-it/

The state fire marshal says when Sugrue pressed her keyless trunk remote, it somehow ignited vapors trapped in plumbing equipment that was stored inside the car.

“In the trunk was an acetylene tank and other equipment used in the plumbing trade. There was a leak in the acetylene tank that caused the explosion based upon the transmittal of the remote,” the fire marshal said.
 

Torgo

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As a liquid, gasoline is not explosive. Gasoline vapor is, however, at the right concentration with oxygen. Same is true for methane (natural gas) and hydrogen. The difference with methane and hydrogen is that it is normally stored as pressurized gases, as are such familiar fuels as propane and butane. Uncontrolled release of that pressurized gas can quickly lead to explosive conditions, and any little spark, like static electricity, can set it off.

caw

*nods wisely* Stoichiometry.
 

Don

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In New Jersey, it is also illegal to pump your gas.
I'll never forget how surprised I was the first time I stopped for gas in Oregon. Is the assumption that people are smart enough to share twisty two-lane roads in inclement weather, with other cars approaching at a closing speed over 100 MPH, and with only inches of clearance preventing catastrophe, but too dumb to operate a gas pump?

Or is it political?
 

clintl

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I'll never forget how surprised I was the first time I stopped for gas in Oregon.

If you pretend you don't know and get out to pump your gas, though, you'll get instant service. Nothing attracts the attention of an Oregon gas station attendant quite like someone starting to pump their own gas.
 

Don

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If you pretend you don't know and get out to pump your gas, though, you'll get instant service. Nothing attracts the attention of an Oregon gas station attendant quite like someone starting to pump their own gas.
No kidding! I was already out of the truck and going for the pump when the attendant stopped me and said I wasn't allowed to use it. The look on my face must have been priceless. I seriously thought I was on Candid Camera or something. It took him a bit to convince me it wasn't a joke.

It must amaze the legislators of Oregon and New Jersey that citizens of 48 other states (and how many other countries?) manage to fuel their cars without blowing us all to kingdom come. :ROFL:

Did the clowns who did this get re-elected? I can't believe anyone would vote for someone who thought they were too dumb to use a gas pump.