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stuckupmyownera
08-28-2010, 02:38 PM
My crazy female character is cornered by her enemies in the kitchen and wants to blow everyone up. After she's turned all the gas rings on, how long before there's enough gas build-up to blow up the whole room? I'm thinking it's gonna be too long - they're closing in and will be able to stop her.

But what if she gave it, say, 20-30 seconds, lit a match away from the hob and threw it onto the hob? Do you think it would cause enough of an explosion to set the ceiling or a nearby curtain on fire? She'd be satisfied if she could burn the place down with them in it.

I'd experiment, but I don't think the landlady would approve...

Kenn
08-28-2010, 03:45 PM
If she turned on all of the rings, then I expect she would be using about half a cubic metre of gas per hour. Explosions for natural gas can happen at about 4 % and less than that for propane. So it would take best part of an hour to fill even a reasonably small kitchen so it would explode completely. You could get a local explosion close to the cooker before the gas had mixed with the air in the rest of the room, however. It could certainly make a bang after 20 or thirty seconds but it is doubtful it would have the calorific value to start a fire unless you were very unlucky (or lucky perhaps!).

Shakesbear
08-28-2010, 05:48 PM
Could she not set fire to something that is on the hob? Chip pan? Or put something in a microwave that would cause an explosion?

jclarkdawe
08-28-2010, 05:53 PM
I agree that your stove isn't likely to produce much of an explosion for at least half an hour or more.

However, use your microwave instead. Shake up several bottles of soda (the more the better), place in microwave on their sides, shut door and cook for a couple of minutes. This is the result of one bottle -- Microwave Explosion - Video. (http://www.google.com/url?sa=t&source=web&cd=6&ved=0CC8QFjAF&url=http%3A%2F%2Fwww.metacafe.com%2Fwatch%2F560274 %2Fmicrowave_explosion%2F&ei=bBN5TO7nNJftnQfk7M3BAQ&usg=AFQjCNHllCkRFO1fKkUttx9d8av53i_l_A)

It's not a great explosion, but for a range of about ten feet, you're going to have flying plastic and boiling liquids. Not likely to be fatal but good probability of needing to visit a hospital.

Best of luck,

Jim Clark-Dawe

lbender
08-28-2010, 06:57 PM
In the movie 'Eraser', Arnold Schwartzeneggar (no idea if I spelled it correctly) pulls the gas hose out of the wall connection and leaves it on. I don't know how fast it would build up, but it should be faster than the stove.

He sets it off by turning the thermostat way up. Sparks from that ignite it. Again, it's a movie, so how realistic the ignition is, I don't know.

Giant Baby
08-28-2010, 07:18 PM
If she's cornered, and there's enough gas present to cause even a small explosion, I can't imagine she'd be able to light a match and throw it without igniting herself at first strike.

Can she have something else handy? Lighter fluid for the grill, or some other propellant she can squirt at them, and *then* throw the match? If you really want an explosion, she could then turn on all the jets while they're fighting the flames and make her escape. That'd buy her some time and distance, and you could still wind up with a nice BOOM as well once she's left the building, or at least made it to the hallway, staircase, fire escape--whatever works for your story.

Unless you need her injured, too. But I can't imagine she's going to have much luck throwing a match.

stuckupmyownera
08-28-2010, 11:35 PM
Hmmm, okay. Thanks everyone. Will figure something out!

Maryn
08-29-2010, 12:45 AM
I used to work customer service for a utility company and fielded questions about the safety of natural gas as part of the job. It ignites only at a very specific level of concentration--too much in a closed space is as non-explosive as too little.

(I just refreshed my memory--it's flammable at concentration levels of 5% to 15% only. See this website (http://www.truenergy.com.au/Residential/Resources/HomeSafety/PropertiesOfNaturalGas.xhtml) for more info.)

When the concentration is just right, the smell of the additive put there specifically to warn people of gas leaks would be extremely strong. It's detectable in concentration of less than one percent. Your crazy woman's enemies are going to smell it well before it's reached ignition levels. They would probably storm her and pin her if they saw any indication of matches or a lighter--or a death wish.

However, when she's pinned, if the concentration is just right, somebody flipping a light switch or otherwise causing a minuscule electric spark can ignite the gas in the air. Since it rises, it could easily ignite the curtains. Which brings in another potential problem, because most commercially made curtains (as opposed to more formal draperies) are not all that easy to ignite. Many are more likely to smolder for some time before there's any flame--or may smolder out.

Has she got an aerosol kitchen product? That and a lighter makes a handy flame thrower...

Maryn, formerly Operator 44 at TG&E

shaldna
08-29-2010, 11:25 AM
My crazy female character is cornered by her enemies in the kitchen and wants to blow everyone up. After she's turned all the gas rings on, how long before there's enough gas build-up to blow up the whole room? I'm thinking it's gonna be too long - they're closing in and will be able to stop her.

But what if she gave it, say, 20-30 seconds, lit a match away from the hob and threw it onto the hob? Do you think it would cause enough of an explosion to set the ceiling or a nearby curtain on fire? She'd be satisfied if she could burn the place down with them in it.

I'd experiment, but I don't think the landlady would approve...


getting gas to explode is actually pretty hard. if the conctration is too low then it won't, but eqally, it won't explode if the concetration is too high either. when gas does explode it's often an impact related incident or a fault - hence you don't hear about alot of gas explosions, but when you do they tend to be mains and are pretty big.

in terms of the rings on an oven, if you turn the gas on and leave it for a few seconds before you light it, yo'll get a small burst of flame, enough to make you jump back.

but most gas cookers are safe in that turning on the gas is not enough, you have to turn on the ring also - on my mothers you have turn the gas on at the wall, and then turn each ring on by turning and holding down the knob.

it would be pretty obvious what she's doing.

Tsu Dho Nimh
09-01-2010, 01:19 AM
If she wants a fast explosion, she needs to disconnect the gas line from the burners upstream of the safety valves and regulators. She can get a larger flow then.

And toss a match in from outside the door and hope for the best.