I know there are certain types of fires that, if one uses water on it, will get worse. But as far as I know, firefighters use water tanks and fire hydrants for virtually every fire too large for a fire extinguisher to do the job.
Is it an issue of if the source isn’t large enough or too far away it doesn’t matter? How do they know the kind of fire before reacting to it?
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> as far as I know
Not quite. Depending on the kind of fire firefighters will use the corresponding chemical or fire fighting technique to not worsen the situation.
It is just the case that water is often easily available, transportable, cheap … and can be used in a lot of scenarios, as there are not often building-sized frying pans burning.
SYL
Short answer, it’s what they have available to them.
Longer answer, if the specific type of material requires specialized chemicals the building should be designed with the correct fire mitigating equipment.
In my jurisidciation any building that has specialized requirements will also have a fire safety plan. It will tell the first responders exactly what to expect. That plan is approved by, and kept on file with the fire department, as well as in a lock box on the exterior of the building.
But then specific things in the building will be properly designed. Like you can’t fight a grease fire with water, so deep fryers must have a chemical suppressant system integral to their implementation, which will go off. But there will also be k-class extinguisher in a kitchen (and the fire department carry these with them too)
Or the material is effectively stored when a fire suppression system isn’t possible. Like with combustible liquids, they’ll be in rated storage tanks, so if there is a fire in the building, the flammable liquids won’t be exposed. Or the fore department can go grab coffee while the building burns itself out (half joking)
i don’t think there are different types of fire, rather different sources of fire. if an oil fire starts in your pan it would be bad to throw water on the pan with oil in it, but once the fire leaves the oil and is burning your wooden walls there’s nothing unique about it and it can be extinguished with water.
Very few structure fires will get worse if you use water and at the end of the day, if there’s wood involved you need water to take the heat away.
Fire trucks do have various additives onboard that can be used. Most departments will have foam on hand or have access if needed for fighting oil/fuel fires. The foam is made by mixing some chemicals with water so they still need a lot of water but also the additives. If they don’t have a source of water available then the foam maker is useless.
Even if there’s a lot of oil on the ground thats on fire, adding water to it will just cause it to float on top. The concern with water in oil fires in houses is because you have a fairly deep container of oil that you’re adding water into which will cause the water to flash boil and push the oil up and out, but unless you have a massive tank of burning oil its not a problem
There are a couple special cases where water absolutely cannot be used but the buildings are generally secured and the fire department will know what buildings they are well in advance so they can prepare accordingly if they get a call. If the titanium mill is on fire you just let that bad boy burn and keep it from spreading because nothing you can do is going to make it better
Because water is almost everywhere and does not cost much, is easy to use and is safe.
The fire engine has a big water tank inside so that when we get to a fire , we can start putting out the fire as soon as we get there. We can put out a small fire with that, a car or some woods on fire. If it’s a bigger fire like in a house, school or big accident, we need more water than we have on the truck. We can get more water from a fire hydrant with a hose from the one down the street. The hose on the back is 1000 feet long and is like a big heavy pipe on top of the road when it has water in it. If we have to get water from a lake or river or ocean, we can connect the hard hose, it’s like a big straw, to the fire pump on the side of the fire truck and suck the water up from the lake and then pump it to another fire truck at the fire. We would use the big hose from the back of the truck for that too. If you have a swimming pool, we can use the fire truck to suck water out of it to put out the fire. Sometimes if there is no fire hydrant or lake out pool, we use firetrucks with bigger tanks to drive the water to the fire. Some are as big as a gasoline truck.
> I know there are certain types of fires that, if one uses water on it, will get worse.
This is true when the fuel for a fire is hydrophobic.
Water puts out fire by getting flammable material wet. This prevents contact between the air and the burning fuel. Fire needs access to oxygen to continue burning because combustion is the chemical reaction between a combustible substance and oxygen when exposed to high heat.
Hydrophobic substances are those that repel, and are repelled, by water. Oil (both cooking oil and petroleum) is hydrophobic. If you take a glass and fill it half with cooking oil and half with water, they will not mix. Even if you stir them they will separate.
Of course oil is combustible. If you leave a pan of oil on the stove, it may catch on fire. (A “grease fire”) You do not want to use water to put it out. If you try, the oil will repel the water and the water will be unable to block oxygen. At the same time, the oil (which you recall is on fire) is going to fly out in every direction, repelled by the boiling water now at the bottom of the pan, setting your kitchen on fire.
So my point is, as long as a fire isn’t fueled by a hydrophic substance, it is safe to use water. Part of firefighters’ job is to understand what exactly is on fire so they can be aware of the risks. There are regulations that anyone who stores large quantities of a hazardous material must report it to the local fire department. Unless a fire site happens to store large quantities of hydrophobic materials, they can safely use water. Otherwise there are chemical alternatives, such as potassium bicarbonate which they use in the form of a fine powder.
There may be some other substances I’m not aware of that would make water unsuitable. But if large quantities of such a material are stored, by regulation that material would similarly be reported to the local fire department.
When you poor it over an open flame, the flame is extinquished. Hence, water puts out fire and why it is used.
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