Suppose you're in a house that's about to explode...

Travis

Misanthrope of the Mountains
Travis
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Mar 31, 2007
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...from say a propane leak. You can't exit the house prior to the explosion but you do have a bathtub full of water and a bunch of mattresses on the other side of the building. Would it be better to seek refuge in the tub of water or behind the mattresses?

This question comes from a long debate we had tonight in my house. Half of us think the tub with water will better protect you from the heat and flames of the fireball but the other thinks the water will better transmit shockwaves into your internal organs making the mattresses a better option.


Any thoughts?
 
Unless the explosion is taking place in contact with the water in the tub, I'd rather take refuge in water than behind a flamable mattress. Behind mattresses also won't help as you are slammed against the far wall and immolated, covering you with flaming plastic debris from the threads of the mattresses.
 
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Hi

If you have time to do either, you'd have time to throw a chair through a window and get the hell out of Dodge.

As it happens, though, Fuel-Air Explosives (FAE) detonates pretty much everywhere, pretty much all at the same time. It's not like a pipe bomb where the explosion is concentrated at one point. As such, the compression wave and the subsequent rarefaction wave also happen pretty much everywhere, pretty much all at the same time.

This is what makes FAE so useful in blowing up cave and bunker complexes.

Go underwater, and the compression-rarefaction combination turns you inside out and stuffs what's left of you into what's left of your own lungs. Go behind the mattresses, and the blast happens, as expressed above as, "pretty much everywhere, pretty much all at the same time," inside your respiratory system, causing similar, but.. ummm... toastier, results.

Well... that's what happened to the monkeys and goats that the Army and Air Force tested explosively-disseminated propane FAE devices on, anyhow.

FAE devices, like your postulated house, are best dealt with from considerable distances. If there's one going off in your house and you can neither stop it nor get away form it, unless you have a vapor-tight blast door to get behind and secure, you're pretty much oddly shaped crispy critter haggis when it's all over.

http://www.metacafe.com/watch/yt-xquGETNoRms/true_fuel_air_explosive_in_slow_motion/

http://www.metacafe.com/watch/yt-GmRASCHJe2Q/blu_96_fuel_air_explosive_fae/

http://www.metacafe.com/watch/yt-j9xCgNdZPKk/fuel_air_explosive/
 
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So, Jack Bauer* is dead either way? My friends will be disappointed with this.




*Yes, a discussion about a scene in 24 is what led to this debate.
 
Travis said:
...from say a propane leak. You can't exit the house prior to the explosion but you do have a bathtub full of water and a bunch of mattresses on the other side of the building. Would it be better to seek refuge in the tub of water or behind the mattresses?

This question comes from a long debate we had tonight in my house. Half of us think the tub with water will better protect you from the heat and flames of the fireball but the other thinks the water will better transmit shockwaves into your internal organs making the mattresses a better option.

Any thoughts?
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I'd pick the water, because I have no idea which one of you is right, but would much rather be instantly jellified than burnt alive.

Hmm... Would a mattress actually do very much about a shockwave? Flying shrapnel, maybe, but wouldn't a shockwave just go through it?
 
Hi

Travis said:
So, Jack Bauer* is dead either way? My friends will be disappointed with this.

*Yes, a discussion about a scene in 24 is what led to this debate.
Click to expand...


Meh. Hollywood explosions work differently. He'll probably just jump into the air and ride the blast wave out of the building.

(FYI: Riding explosion compression waves is not a safe thing to do. Unless you are quite familiar with being accelerated to the speed of sound in a few milliseconds, the results can be somewhat demoralizing.)
 
Travis said:
So, Jack Bauer* is dead either way? My friends will be disappointed with this.




*Yes, a discussion about a scene in 24 is what led to this debate.
Click to expand...
Fuel-air explosions (or gas explosions) are quite soft, as explosions go. This is because the shockwave is mostly subsonic. If the gas/air mixture is really all over the house, it will also be in your lungs, do hold your breath to keep it from propagating into your lungs, as this has unpleasant side-effects.

However, in real gas explosions, the critical mixture is normally only in part of the area, because the gas is normally either lighter or heavier than air.

If you are under water, the water should protect you against burns, but the explosion will tend to demolish the house, which will probably deprive you of that protection.

Mattresses, depending on the type, may protect you against flying debris and directly scorching by flames, but will give a larger area for the shock wave get a hold to propel you wherever it tries to propel. Foam plast mattresses are to be avoided like the plague, impending explosion or not.

In real life gas explosions, it is not uncommon for the house to be completely demolished and the inhabitants to be thrown for considerable distances. However, due to the "soft" character of the shock wave, it is not unusual that most injuries, apart from burns, incur when landing.

Hans
 
Let us suppose that the propane line that is busted open is in the kitchen and there is an already existing fire in the nearby living room. Now you can go to the back of the house where my previous scenario is setup but you can't leave the house because of armed gunman surrounding it. So the explosion, when it happens, will occur when the cloud of propane gas reaches the flames in the living room.

Given that, which would be better?
 
Travis said:
...from say a propane leak. You can't exit the house prior to the explosion but you do have a bathtub full of water and a bunch of mattresses on the other side of the building. Would it be better to seek refuge in the tub of water or behind the mattresses?

This question comes from a long debate we had tonight in my house. Half of us think the tub with water will better protect you from the heat and flames of the fireball but the other thinks the water will better transmit shockwaves into your internal organs making the mattresses a better option.


Any thoughts?
Click to expand...

so you debated about bathtub or mattresses..
i would have called someone to fix the propane leak :D
 
Travis said:
Let us suppose that the propane line that is busted open is in the kitchen and there is an already existing fire in the nearby living room. Now you can go to the back of the house where my previous scenario is setup but you can't leave the house because of armed gunman surrounding it. So the explosion, when it happens, will occur when the cloud of propane gas reaches the flames in the living room.

Given that, which would be better?
Click to expand...

Having seen the pictures of natural gas deflagration experiments carried out by our neighboring lab, I think the correct answer is "No."

Between the two, I'd pick the tub because tubs are comforting, and I want to die with some comfort rather than dragging some mattresses around.
 
blutoski said:
Sounds like an experiment for Mythbusters.
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They already did the bug-bomb experiment. That seemed quite survivable (no detonation). Humans are actually quite robust against pressure waves, which is why shrapnel producing munitions are used. A bathtub would protect you against flashburns.

//CyCrow
 
It's a lot harder to get a propane/air mix right to explode and MRC is right, the pressure wave is pretty low as explosives go. This is fortunate or we'd have a lot more problems given the easy availability of propane.
 
Travis said:
Let us suppose that the propane line that is busted open is in the kitchen and there is an already existing fire in the nearby living room. Now you can go to the back of the house where my previous scenario is setup but you can't leave the house because of armed gunman surrounding it. So the explosion, when it happens, will occur when the cloud of propane gas reaches the flames in the living room.

Given that, which would be better?
Click to expand...

Dude, what's next? Ninjas? ;)
 
Dunstan said:
I'm told hiding in a refrigerator is helpful.
Click to expand...

Well, maybe....
But then, I'd have to squeeze next to something that's been in there far too long and I can't tell whether it's cake or meat. Meatcake???
 
So a propane explosion is soft enough where using the bathtub with water might actually help?

Now would you need to leave your AK-47 outside the tub or should it be brought into the water with you? You'll need it, afterwards, to fight off the rest.
 
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