can someone explain the science behind why getting fire wet puts it out?
In: Chemistry
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.
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