can someone explain the science behind why getting fire wet puts it out?
In: Chemistry
Water suffocates fire. Water is not flammable and putting a layer of it on whatever is burning immediately cuts off the flame’s oxygen supply. It does heat up immediately and turn to steam, but that’s solved by adding more water.
Water doesn’t work on some types of chemical fires.
To understand fire, you need to understand the Fire Triangle.
Fire is the result of 3 things: Heat, Fuel, and Oxygen
You need all three of these things for a fire to ignite.
Water puts out a fire because it robs if of 2/3 of those things. It displaces air so the fire has no oxygen, and it removes heat.
There’s something called a fire triangle. One side is fuel source, one side is oxygen, the other side is ignition source. A fire can only occur when it has each side, take away a side and then the fire goes out. Water takes away a side.
Fire need air. Water block air, so no more fire. Kinda like you. You need air, water block air, then no more you.
I’m just gonna try and pad the rest of this with bs so I dont get auto-modded, but there’s really not much else to say. The mechanism is painfully straight forward. Not much science to talk about.
EDIT: though there’s other fuel sources besides air, but still, the physical mechanism is the same. Block the fuel, kill the fire. Water simply blocks the air in a conventional air fueled fire. Do not pour water on electrical or grease fires, those need something else to block their fuel source
Fire is hot. Water is not.
Fire transfers heat to water and makes the water hot. Water takes _a lot_ of heat to be converted to steam. If it loses enough heat, fire dies.
Water also replaces oxygen. Fire needs oxygen, or it dies.
If you have enough water to replace oxygen and to absorb the heat from fire, the fire dies
Is the same reason a piece of wood cant light instantly when put on a flame. The wood needs to be hot enough to ignite. The water removes a ton of the heat in the fire which leads to the fire being unable to sustain itself hense extinguishing.
It’s actually called the Fire Tetrahedron, the 3 that everyone else said.. heat, oxygen, fuel. But the 4th is the chemical reaction that makes it interact together.
Source: am a firefighter
Fire like all runway chemical reactions need energy to keep going called an activation energy. Without reaching this threshold the reaction will slow until it dies. Adding enough water or any non flammable liquid that has a high specific heat (amount of energy required to increase in temperature) will sap the energy from the reaction and kill it. Even if the water your adding is instantly vaporized if enough energy is removed the fire dies. The water doesn’t remove oxygen but rather removes energy.
Oh boy, I get to use the stuff I learned from my old job. I’ll do it in the appropriate manner first and then go a little more into detail.
EXPLAINING LIKE YOU’RE FIVE
Think of when someone is making a cake. You have your eggs, your milk, your flour, and sugar. (I’m not a baker but I’m just using this as an example.) You need to have all four of these things to make a cake. If you remove one of the ingredients, you won’t make a cake. Water removes one of the ingredients in the cake that is fire.
WORDY SCIENCE BASED ANSWER
Allow me to present to you the[ Fire Tetrahedron](https://fire-risk-assessment-network.com/blog/fire-triangle-tetrahedron/). It shows that there are four things required for a fire to occur: heat, oxygen, fuel, and a chemical reaction. Once you disrupt one of those elements, the fire is unable to continue and will fade out.
Water is known to disrupt chemical reactions, can quickly lower the temperature, and separate the fire from the fuel. The amount of oxygen inside of it can become an issue, depending on the situation and described a little below, but the other disruptions can mitigate or potentially eliminate that as a risk.
Now, this changes *wildly* if you go with a different class of fire. There are five classes of fire:
A – Ordinary flame hazard. This class refers to wood, paper, fabrics, textiles, etc.
B – Liquid flame hazard. This class refers to motor oil, gasoline, tar, petroleum based oils, ethanol based fluids, alcohol based, and others that aren’t listed.
C – Electrical flame hazard. This class refers to home appliances, breaker panels, generators, even the electrical components to your car that are energized.
D – Metal flame hazard. This class refers to products that contain potassium, titanium, iron, or even lithium metals.
K – Kitchen flame hazard. This class refers to animal oils, fats, vegetable oils, and other related products found in the kitchen.
What would work for a class A fire does not always work for the others and may even exacerbate their severity. Ever been told to never add water to a grease fire? That’s part of the reason why. Whenever water that’s, for example, room temperature or even boiling hot, is added to a grease fire, the temperature is already well above 350-450 degrees Fahrenheit. Once the water is added to the mix, the water’s temperature shoots up at a near instant rate and change form from liquid to gas. Because of the sudden addition of oxygen, the grease fire becomes *much* more energetic and…well, [watch this and you’ll see. ](https://www.youtube.com/watch?v=9xGNFj_su_s)
Now, let me blow your freakin’ mind on this one: water will *not* put out a potassium fire. In fact, water could make it *far* worse for a similar reason as the grease fire. [Here is an example of what could happen when potassium is introduced to a supply of water. ](https://www.youtube.com/watch?v=Jy1DC6Euqj4)[Here is one where a couple of mad lads decided to throw some sodium into a body of water. ](https://www.youtube.com/watch?v=5UsRiPOFLjk)
Source: I worked in fire protection for the better part of a decade and had to give multiple classes and trainings on this topic.
Can you breathe underwater? Neither can fire
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