Question (science related)

apeZ

apeZ

apeZ

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A little random, but I was thinking about this earlier...

If there is a fire, does it make a difference if you use hot or cold water to put it out?
 
Not really, you could use Heavy Water, Dideuterium monoxide, if you wanted and it'd still put the fire out. It all depends on what's ablaze though really.
 
In theory cold water, in practice it doesn't really matter much.

The general idea of covering fire with water is that it is not flammable and suffocates the fire. I guess the hotter the water is the easier it would be for the fire to vaporise the water as it would take less energy and time for the water to turn to steam.

amirite?
 
I'm sure there's probably a balancing point somewhere.

It would depend entirely on:

Temperature of hot water (i.e. is it close to boiling point or near freezing?)
Quantity of water
Dispersion of the water as its sprayed or poured
Intensity of the fire

I'm sure there's a point at which the water *could* be near boiling point, lacking enough volume, far too dispersed, and just turned into steam or vapour.

I could be completely wrong though and everything above is rubbish.
 
mp3kla said:
I'm sure there's probably a balancing point somewhere.

It would depend entirely on:

Temperature of hot water (i.e. is it close to boiling point or near freezing?)
Quantity of water
Dispersion of the water as its sprayed or poured
Intensity of the fire

I'm sure there's a point at which the water *could* be near boiling point, lacking enough volume, far too dispersed, and just turned into steam or vapour.

I could be completely wrong though and everything above is rubbish.
Click to expand...

I would imagine cold water due to it needing energy to reach its specific heat capacity and it's high latent heat of vapourisation (Nerd words F.T.W) ;) which it could take from the fire's 'energy'
 
Fire needs three things:

Heat, Oxygen, Fuel.

You need to take one away to stop a fire, CO2 takes oxygen away, water takes heat away.

Hotter water will take less energy to boil, and therefore evaporate quicker (therefore removing itself) and remove less heat, meaning you need more of it.

So colder water would be better.

Liquid *insert something non flammable and very cold here* would be better.
 
Skyfall said:
Correct me if i'm wrong but fire does not need heat, it generates heat. I.e. you can light a fire in the depths of space al long as you have oxygen.
Click to expand...

Fire needs heat to sustain itself, if you cool it it stops.

But I think you are right in the fact that you don't need heat to start it, just some kind of spark/reaction.
 
You can put your hand in fire without being burnt depending on the source, cold water is better as it takes more energy to evaporate it.
 
Energize said:
You can put your hand in fire without being burnt depending on the source, cold water is better as it takes more energy to evaporate it.
Click to expand...

That's generally because of the time your hand is in there and the time is takes for your hand to heat up/feel the heat.

But yes, things like alcohol burn at a comparatively low temperature.
 
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