Fire vs. Handgrenade

[Shroom Man 777]

Just a simple moronic question. If there was a fire, not a really big one, but big enough to be a sizeable impedement, and I chuck a hand grenade into it, what happens? There's an explosion, yeah, but does it kill the fire?

[kheegster]

I doubt it, since the explosive charge in a typical hand grenade isn't much at all, since they derive their killing power from fragmenting into tiny pieces of shrapnel.

[Admiral Valdemar]

Chuck a few sticks of TNT in. That'll stop the fire. And likely make whatever the fire was destroying that you wanted to save a nice crater to boot.

[Stofsk]

Chuck a few sticks of TNT in. That'll stop the fire. And likely make whatever the fire was destroying that you wanted to save a nice crater to boot.

Fight fire with fire.

[AMX]

Chuck a few sticks of TNT in. That'll stop the fire. And likely make whatever the fire was destroying that you wanted to save a nice crater to boot.

Bad idea.
If you don't have a proper detonator in there, chances are the TNT will burn, rather than explode.

[Azazal]

Chuck a few sticks of TNT in. That'll stop the fire. And likely make whatever the fire was destroying that you wanted to save a nice crater to boot.

Showing once again that there is no problem that high explosives can't solve

[kc8tbe]

Not a moronic question at all. I think you've actually got a chance if you through the hand grenade at the base of the fire.

If this fire is a combustion reaction, it requires three things to "live":
1. Oxygen
2. Fuel
3. Heat

By throwing an explosive into the fire, you could hope to do two things.
1. Displace a large amount of oxygen in the explosion, enough to snuff out the fire (like blowing a candle out). I don't think your hand grenade is big enough to do this, though the TNT might work.
2. If the grenade makes it to the base of the fire, the explosion might drive some of the fuel out of the heat of the fire. Like spreading the remains of a campfire around with a poker.

Bad idea.
If you don't have a proper detonator in there, chances are the TNT will burn, rather than explode.

A valid concern. The byproducts from burning a stick of TNT include nitrogen oxides, which are quite toxic.

[Deathstalker]

Using explosives is how oil well fires are blown out and capped. An explosive charge is dropped into the fire then detonated, using up the oxygen.

A fragmentation grenade doesn't have much explosive power most likely only having a chance of effecting small fires. Thermite grenades are right out of course!

[Admiral Valdemar]

Pfft, you'd obviously have the sticks fuzed and lit as they were thrown, then they'd go off hopefully before they melt. Or you can just chuck a vial of nitro in. That'd be fun.

Using explosives is how oil well fires are blown out and capped. An explosive charge is dropped into the fire then detonated, using up the oxygen.

A fragmentation grenade doesn't have much explosive power most likely only having a chance of effecting small fires. Thermite grenades are right out of course!

The Thunderbirds episode "Terror In New York City" (the one with the moving of the Empire State Building) opens with an oil well fire in the US where the Firefly'dozer fires an explosive charge into the inferno. The blast blows out the fire and the oil flows free. That's pretty much the only way to stop such intense blazes short of cutting off the supply of fuel somehow or using halon gas bombs.

[Deathstalker]

"Hellfighters" with the Duke and Jim Hutton is about a company that handles oil well fires.

[Shroom Man 777]

How about an HE grenade? Or do these only exist in counterstrike...?

[Deathstalker]

Here is a link for US grenades

Things that go BOOM!

HE hand grenades are not useful, because the explosion isn't focused very well. Better to use explosives for destroying things.

However Make things go BOOM farther away

40mm grenades have HE rounds, which are really just hopped up frag grenades.

Safety tip, do not use Mk19 rounds in a M203 launcher.

[Darth Wong]

Does anyone know what kind of overpressure is required to blow out a fire?

[Admiral Valdemar]

That really depends on many variabilities within the scenario, such as what fuels the fire, how much open space is available and so on. I'll see if I can look anything up, but it would take quite a bit of HE to stop something like an oil well, compared to a paper warehouse.

[Sea Skimmer]

Just a simple moronic question. If there was a fire, not a really big one, but big enough to be a sizeable impedement, and I chuck a hand grenade into it, what happens? There's an explosion, yeah, but does it kill the fire?

A hand grenade is a pretty substantial explosion at close range, especially if it was a concussion grenade, which has eight times more then the average of about 1oz of explosive in fragmentation grenades. Fire would be blown out a very short distance away, but then it might just reignite from the latent heat and any remaining flame would quickly spread the fire back. Grenades are something to start fires with, using one to put out a fight is not something I’d ever consider. When you use explosives to blow of things like oil fires, its very important that the blast be in the AIR above the fire, throwing a grenade doesn’t give you that.

[Darth Wong]

TNT would use up a lot of oxygen during the afterburn because it's such a chemically underoxidized explosive, but I don't know if that would outweigh the detrimental effect of the TNT generating its own fireball in the process. It would be nice to know exactly what types and sizes of explosive charges they used when putting out oil fires in this manner.

[Admiral Valdemar]

I have a friend who's a part time fireman (and my barber), I'll ask next time I'm in, probably this week, if he or his colleagues know anything on this kind of thing. They've trained at airports before which deal with kerosene fires, so potentially someone knows about more exotic fire hazards and dealing with them.

[aerius]

TNT would use up a lot of oxygen during the afterburn because it's such a chemically underoxidized explosive, but I don't know if that would outweigh the detrimental effect of the TNT generating its own fireball in the process. It would be nice to know exactly what types and sizes of explosive charges they used when putting out oil fires in this manner.

From what I remember of my university geology course, it's usually nitroglycerine based explosives and sometimes TNT. For a smaller fire they use maybe 50-100 pounds, and for larger ones they'll use several hundred pounds.

The explosion momentarily blows out the fire, which is why they need to keep lots of fire hoses trained on the fire before, during, and after the blast to keep the well from reigniting. Without the water, the oil will just light itself again from the hot material around the wellhead.

[Darth Wong]

Nitroglycerine, interestingly enough, does not require oxygen. The nitroglycerine molecule already contains enough oxygen to oxidize itself completely (to be more precise, it contains 3.52% more oxygenthan it needs to split into various reaction products which are all fully oxidized). This is probably part of the reason why the stuff is so unstable in its unaltered form.

[Admiral Valdemar]

It's more to do with the arrangement of the trinitrate bonding within the molecule and how easy it is for that bond to break and cause a chain reaction (if you're lucky, deflagration. Unluckily, it's usually detonation, especially if you've not made some crappy homemade NG with dinitrate bonds instead). You can cool or mix the stuff with substrates, which is of course, how we got TNT. But I'd rather go with plastique because of the more stable compounds formed in incredibly stable polymers, given nitrogen really wants to get back to its stable state, which means boom. All explosives are unstable, but nitro and old dynamite that's got a bit sweaty from age/heat are ones to avoid.

[Faram]

TNT and other explosives is great stuff to start fire with, they burn hot and ignite easely.

But to put out a fire? Not likly unless you blow away all burnable stuff.

Happen to know this because a stick of Plastique was our favorite way to start a fire in the army, much safer end easier to handle than kreosone or disel.

And only a fool tries to use gasoline.

[Winston Blake]

How about an HE grenade? Or do these only exist in counterstrike...?

Given that the U.S. is already making 40mm thermobaric grenades, and that process is designed specifically to produce as much overpressure as possible, may6be some kind of thermobaric hand grenade could put a fire out? There's also the fact that they burn as much atmospheric oxygen as possible. However, the intense heat would probably mean that even if it worked, the fire would reignite soon.

[AMX]

You can cool or mix the stuff with substrates, which is of course, how we got TNT.

Actually, that's how we got Dynamite, not TNT.

Also "trinitrate bonds" and "dinitrate bonds"?
You may want to brush up on your chemistry a bit...

[Shroom Man 777]

A hand grenade is a pretty substantial explosion at close range, especially if it was a concussion grenade, which has eight times more then the average of about 1oz of explosive in fragmentation grenades. Fire would be blown out a very short distance away, but then it might just reignite from the latent heat and any remaining flame would quickly spread the fire back. Grenades are something to start fires with, using one to put out a fight is not something I’d ever consider. When you use explosives to blow of things like oil fires, its very important that the blast be in the AIR above the fire, throwing a grenade doesn’t give you that.

How fast would the fire reignite? And what would a thermobaric grenade do to a fire?

[Admiral Valdemar]

Actually, that's how we got Dynamite, not TNT.

One of the two, guess I should correct one newsgroup poster on that too.

Also "trinitrate bonds" and "dinitrate bonds"?
You may want to brush up on your chemistry a bit...

Not actual bonds, obviously, as they don't exist. I meant as in the way the molecules are arranged to form that compound with the oxygen. The interaction between an unstable nitrate along with the oxygen only makes for more volatile an explosive, I suppose a better term would be pairing and talking about the valency, rather than say bonding, hmm, does reread odd after a night's sleep. The cooling or inclusion of a substrate makes such energy levels less likely to be returned to a stable valency state resulting in a bang.