[vdblnkr34 (OP)]

Hi. I come up with extinguisher that can kill forest fires. I call it CO2 bomb.

Looks like American-football ball, but bigger. inside is lots of liquid CO2.
Drop one in the forest fire. Valves will open and release huge amount of liquid CO2, which will become gas. 

[chiralSPO]

A forest fire is already producing significant amounts of CO₂ as it goes. Probably orders of magnitude more than you could hope to deliver by airplane/helicopter. So really, this would just be providing cold (absorbing heat). Pound for pound (and weight is mostly what matters when flying), water is much more effective at absorbing heat than CO₂ is. And we already drop water from the sky onto fires.

[vdblnkr34 (OP)]

You are talking about CO2 which is after burn, above the fire and already hot. Im talking about CO2 on the ground level, which is slightly below the fire and has a temperature of negative 2xx blah blah blah and its in a liquid state. That will take even more heat away from the fire. At the end some CO2 will convert into CO and everything will turn into a huge smoke. Than water can be used to extinguish the rest.

Actually, should work.

[vdblnkr34 (OP)]

Check what happened in Australia a while ago. Water didnt work.

[Bored chemist]

Actually, should work.

Water works better, and is very cheap.

 

Im talking about CO2 on the ground level, which is slightly below the fire and has a temperature of negative 2xx blah blah blah and its in a liquid state. That will take even more heat away from the fire.

OK, so imagine you use water.
It also falls to "ground level, which is slightly below the fire", it also gets boiled (because 100C is a lot colder than a fire).
Water also "will take even more heat away from the fire".

Why do you think CO2 is good?

[vdblnkr34 (OP)]

Because with the temperature above 10,000C water sets on fire. CO2 wont do that.

[chiralSPO]

with the temperature above 10,000C water sets on fire

Firstly, water doesn't burn at any temperature (at extremely high pressures and tens of millions of degrees inside a star, water could undergo fusion, which some people call burning, but that is not relevant).

Secondly, fires are not 10,000 degrees (Faranheit, Celsius (centigrade), Kelvin, and Rankine are the only common temperature scales I know of, and even the hottest commonly available flame—H₂/N₂O—is only about 3500 °C, which is about 6800 degrees Rankine)

[Bored chemist]

Because with the temperature above 10,000C water sets on fire. CO2 wont do that.

You seem to be trying to pretend that water does not put out fires.

It may be understandable that you don't realise fires don't get to 10,000C, or even that you don't realise that water wont burn no matter how hot you get it.

it really does make you look foolish if you say that water won't put fires out because it burns.

[vdblnkr34 (OP)]

Im not telling to change water for CO2, to use CO2 as complementary to extinguish huge fires. Due to high cost of CO2, no one tried this.
Ask fire fighter about why huge fires when they arrive dont get extinguished right away. They stand and wait for something.

Some fires water cant help to get rid of. You cant pour water in one shut all over the place of fire, CO2 you can.
Its impossible to dump 100T of water in one shut.

[alancalverd]

Carbon dioxide is indeed a good fire extinguisher in a confined space where it can displace oxygen. Now consider a very small forest fire a kilometer in diameter with trees 50 m high.To extinguish it with CO2 you need to supply about 40,000,000 cubic meters of CO2 in one drop. At 2 kg/m³ that's 80,000 tonnes. If you don't drop it all in one go, it will blow away and the fire will reignite.

The value of water and various liquid and solid fire suppressants is their persistence. You can bomb a strip to stop the fire spreading, and thus isolate the damaged area. Doesn't work with gases.

[Bored chemist]

Im not telling to change water for CO2, to use CO2 as complementary to extinguish huge fires. Due to high cost of CO2, no one tried this.
Ask fire fighter about why huge fires when they arrive dont get extinguished right away. They stand and wait for something.

Some fires water cant help to get rid of. You cant pour water in one shut all over the place of fire, CO2 you can.
Its impossible to dump 100T of water in one shut.

None of that makes any sense.
In the real world, people put out fires with water.

[Petrochemicals]

Hi. I come up with extinguisher that can kill forest fires. I call it CO2 bomb.

Looks like American-football ball, but bigger. inside is lots of liquid CO2.
Drop one in the forest fire. Valves will open and release huge amount of liquid CO2, which will become gas. 

Fires need heat fuel and oxygen, you need to remove one to extinguish the fire. You cannot reliably remove the oxygen from a fire for a sustained period, nor the fuel in any reasonable scenario using fire suppressants etc, so you need to remove the heat. Extinguishing the fire may remove the heat from a small fire long enough to cool the fire but a large fire needs cooling down a great deal, this is why the fire brigade spend long periods dampening fires and raking through material piles.

Co2 from solid to gas I would bet has a far smaller  energy requirement than liquid water to gas.