How does water extinguish fire?

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Discussion Overview

The discussion revolves around the mechanisms by which water extinguishes fire, including the roles of oxygen, fuel, and heat. Participants explore the scientific principles behind combustion and the cooling properties of water, with a focus on both general understanding and specific applications such as in nuclear reactors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants state that fire requires oxygen and fuel, and that water extinguishes fire by cutting off access to oxygen and cooling the fuel below combustion temperature.
  • One participant expresses curiosity about combustion temperature and seeks clarification on why water is an effective cooling agent, particularly in nuclear reactors.
  • Another participant explains that water has a high specific heat, which means it requires a significant amount of energy to raise its temperature.
  • Participants clarify that fire needs three components: oxygen, fuel, and heat, and discuss the ignition process of a match as an example of these principles in action.

Areas of Agreement / Disagreement

Participants generally agree on the basic principles of fire extinguishment by water, but there are varying levels of understanding regarding specific terms and concepts, such as combustion temperature and the properties of water as a cooling agent.

Contextual Notes

Some participants express uncertainty about specific terminology and concepts, such as combustion temperature, indicating a need for further clarification. The discussion does not resolve these uncertainties.

Who May Find This Useful

This discussion may be useful for individuals interested in basic fire science, the properties of water, and applications in safety and engineering contexts.

MR
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How does water extinguish fire? My 5-year-old brother asked me, and now I'm really curious.
 
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Fire needs two things: oxygen and fuel.

Water cuts off access to oxygen, and cools the fuel to below combustion temperature.
 
OK, now I'm feeling REALLY ignorant...
What's combustion temperature?
Also, I've heard a number of times of using water as a cooling agent (especially in nuclear reactors), but why does water cool things down so well?
Thanks!
 
MR said:
Also, I've heard a number of times of using water as a cooling agent (especially in nuclear reactors), but why does water cool things down so well?
Thanks!
water has a high specific heat, meaning it takes a lot of energy/heat to increase the temperature of 1 gram of water by 1 degree celsius
 
imabug said:
Fire needs two things: oxygen and fuel.

Water cuts off access to oxygen, and cools the fuel to below combustion temperature.
Make that 3 things: oxygen, fuel, and heat. Your description has all 3.

MR, when you strike a match, you are using friction to increase the temperature of the phosphorous on the match head above its ignition temperature - the temperature at which it starts to burn. After it starts to burn, it expends more energy than is needed to keep the fuel burning - so it stays lit.

Welcome aboard!
 
Last edited:
russ_watters said:
Make that 3 things: oxygen, fuel, and heat. Your description has all 3.
right, heat. i always make that mistake. I figure if you're talking fire, heat's pretty much a given.
 
Thanks, people...This is so cool!
 

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