How to Use a Fire Extinguisher

I am big on preaching the benefits of readiness against the most probable threats, as my long time readers will no doubt attest. One of the single most common everyday crises a prepper may have to deal with is a fire.

Fires are serious threats, and can happen anywhere, and virtually anytime, from a variety of causes. IN 2017, there were over 1.3 million damaging fires of all kinds reported. Of those, over 300,000 were house fires. The final toll in death and damage was 3,400 dead, 14,600+ injured, and property damage totaling over $23 billion, billion dollars.

With figures like that combined with the statistical likelihood of a fire occurring compared to, say, total economic or social collapse, if you don’t have a comprehensive fire response plan laid out and drilled, you are wrong.

You can keep a small incidental fire from turning into a deadly conflagration and life-ruining disaster by keeping a quality fire extinguisher handy and knowing how to use it. In this article, we’ll have a look at what’s what when it comes to fire extinguisher tech and what you need to know to get your amateur firefighter on.

Dealing with Fire

Dealing with fire is a tricky thing for the average person. Fires at home, your workplace and in your vehicle will be your biggest potential threats requiring you to use a fire extinguisher in an attempt to make a safe escape or snuff a little fire out before it becomes an unstoppable blaze.

Ideally, you’ll have a variety of fire extinguishers at or in all three locations to deal with whatever kind of fire that occurs. For example, you might have a large, all purpose can at home for dealing with dry material, grease and electrical fires, a smaller unit mounted in your car, and then whatever kind is appropriate for your work, assuming you do not work for someone else in a building with pre-furnished extinguishers,

The rub is that most fires grow fairly quickly much of the time, and in ideal circumstances (or from applying the wrong agent) they can spread with shocking speed and intensity. Any person will have a limited window to successfully contain a fire before it gets completely out of control, and then you’ll simply need to abandon ship and try to escape with your life.

Time will be of the essence, so it is crucial that you know both what kind of fire extinguisher to utilize and how to use it to best effect. We have a look at both below, starting with types and ratings of fire extinguishers.

Understanding Fire and the Fire Triangle

To fight something, one must first know it. Fire is no different. For any fire to ignite, there must three elements present, known as the Fire Triangle. If you take away any one element, the fire goes out. Think of it like a tripod: to topple any tripod, you only need to break a single leg.

The trick is understanding how different types of fire process the triangle. Chemical fires may be far harder to put out than simple common material fires. Metal fueled fires can be among the very worst to deal with, though thankfully are quite rare unless you work in an industrial or lab setting where they typically occur.

Those three elements composing the fire triangle are:

  • Heat – Without sufficiently high temperature, a fire cannot start or continue.
  • Fuel – Without fuel a fire cannot burn. Removing the available fuel to a fire will lessen its intensity until existing fuel is consumed.
  • Oxidizer – No oxygen, no fire, and less air means a slower burning, weaker fire. This is usually the air around a fire but can be a chemical oxidizer. Chemically oxidized fires can be very tough to put out.

Fire extinguishers work by attacking one or more legs of the triangle. CO2 extinguishers displace oxygen near the fire and introduce a blast of cold. Chemical agent extinguishers  may absorb more heat than water in addition to smothering the fuel source, etc.

fire extinguisher

Types of Fire Extinguishers

Fire extinguishers are not a one-for-all solution (though some come close). Instead, each unit will utilize a specific agent that is effective against one or more types of fuel. It is absolutely critical that you choose an extinguisher for the type of blaze that is most likely to occur, though thankfully the most common residential extinguishers will handle the three most common causes of fire you are likely to encounter.

All fire extinguishers will be marked with their type(s) and rating on the unit for simple, quick identification and reference at a glance.

  • Class A – denotes an extinguisher for ordinary materials fires; wood, paper, plastics, etc. Its symbol is a green triangle.
  • Class B – for fires fueled by combustible liquids like gasoline, kerosene and oils. The geometric symbol for a Class B extinguisher is a red square.
  • Class C – for fires involving electrical components like wiring, circuit breakers, appliances, etc. The geometric signal for a Class C unit is a blue circle. Of important note is that a B rating specifically indicates an extinguisher containing an agent that is electrically non-conductive. You definitely cannot fight an electrical fire with a water extinguisher! The risk of shock is certain!
  • Class D – For fires involving combustible metals. Fires of this nature are very nasty and thankfully rare outside of lab and certain industrial settings. These extinguishers are specialized for the fires they fight, and you will not see multi-purpose models. Their symbol is a yellow star, or decagon.
  • Class K – For animal fats, cooking oils and similar commonly encountered in kitchens. The symbol for these is a black hexagon.


Among Class A, B, C and multi-purpose extinguishers above, you will encounter a few common varieties.

Water Extinguishers – Ah, water. The perennial foe and weakness of fire. What could be better and more fool proof than dousing a fire with water? Especially air-pressurized water? Well, if you are fighting a class B, C or D fire, almost anything! Water will make the fire worse!

Anyone who has seen a little grease fire in a pot turn into a towering inferno after a hapless, panicking cook throws a glass of water on it knows the scoop already. Any fire that is class A can be easily handled by a water extinguisher, but no others can. For that reason, they are of limited utility and we will be best to avoid them unless we have no other choice.

Dry Chemical – A variety of types are available. These utilize either a powder or foam delivery and can fight some combination of A, B and C fires. Their multi-purpose nature makes them ideal for home and vehicle preparedness, though they have a couple of special drawbacks.

  • Sodium Bicarbonate or Potassium Bicarbonate – For BC fires. Leaves mildly corrosive chemicals behind that must be neutralized to prevent surface damage.
  • Monoammonium Phosphate – For ABC fires. These are the kind that leaves behind a sickly-looking mustard yellow cloud of sticky goo. This is a great all around extinguisher, but the material is damaging to electrical components even from incidental contact.

Both of these varieties leave residue behind on combustible materials and the source of the fire itself, greatly reducing the chance of further re-ignition. These are mainstays.

Carbon Dioxide – Shoots exactly what it says on the tin. Extinguishers of this type fire, sorry, poor choice of words, shoot a stream of gaseous CO2 from the nozzle under immense pressure. Will handily put out B and C fires, but not the best choice for A fires. Also these leave no smothering residue behind, and so the chance of re-ignition is greater than with our dry chemical varieties above. The good news is that CO2 extinguishers will not harm electrical components.


A fire extinguisher’s rating is denoted by a number before its class. The numbers mean different things by class. For instance, for A class fires, the number denotes an equivalent fire-fighting capability of 1.25 gallons of water for every value of its rating. So a “1” rated A extinguisher is equivalent to 1.25 gallons of water. A “2” rating would be 2.5 gallons of water, and so on.

The rating for a B class extinguisher denotes the size of the fire it can fight in square feet, typically in 10’s of feet, approximately. So a 10B extinguisher can fight a 10 square foot fire, a 20B a 20 square foot fire, etc, etc.

Note these ratings are not in conjunction. You might have a 2A-20B model, for instance. The most important tip you can remember is that bigger is always better on rating, as it indicates the extinguisher is capable of fighting a larger fire.

Using a Fire Extinguisher Effectively

When you smell smoke and can hear the flames popping, it is not time to figure it out as you go. Fire extinguishers are simple to operate, but you should be familiar with the following mnemonic to help you use it to best effect.


Pull the Pin – Make like it is a grenade and pull the pin from the extinguisher valve assembly. Use force, as some are held in with a split pin, security tie, or other retaining mechanism. Don’t throw the extinguisher.

Aim low – Grasp the handle with one hand and the nozzle or projector with the other. Aim the nozzle at the base of the fire, where the fuel is, not at the jumping flames.

Squeeze trigger – You need to get agent going on to the fire to do any good. Hold the trigger or lever down and get to work. Adjust aim as needed; some models will have a little recoil.

Sweep side to side – The idea is to saturate the base of the fire and area immediately around it with agent until it is totally out.

How to Use a Fire Extinguisher

Keep Your Head

Whatever you do, take a moment to assess the situation before you commit to battling the blaze. Modern chemical fire extinguishers are highly effective, but you must use them correctly and there will be times when the fire has grown too large or is spreading too quickly to stop.

That’s why it is important to take stock of the situation as a whole before you commit to battling a fire. No property or belongings are worth your life or the lives of someone else. Your intervention could be futile and simply waste valuable time if the situation is already out of hand.

You may be on the verge of panic when confronted with a fire, but remember: time spent thinking clearly is never wasted! Ask yourself the following questions before you pull the pin and go to town: Do you have a clear path of retreat or certain escape now, or might the fire potentially cut you off if you fail to contain it or if you delay?

Are you in danger of being overcome by smoke? Asphyxiation is a primary cause of death and incapacitation from fire. You may be fit as fit gets, but a few big lung-fulls of smoke will let the wind out  of your sails quickly. Stay as low as you can at any rate, and if you have time a wetted cloth tied over the mouth and nose may offer marginal protection against smoke inhalation.

Is there anyone that may need rescuing? If there are others depending on you to get them out of harm’s way, your time may be best spent doing just that instead of fighting a fire directly. Smoke buildup will make searching geometrically more difficult the longer you wait, so move quickly if this is the case.

You can nip a fire in the bud if you put it out quickly enough, but you’ll also need to decide just as quick if you should try or use what time you have for other ends. Most of you are not trained fire fighters, but a trip to YouTube and elsewhere on the internet should yield plenty of informal education on how quickly you can expect a fire to worsen when started on a variety of material.

Lastly, please consider that, no matter the situation, no material belonging is worth your life or the life of another. Fire is unpredictable, and can multiply in size and intensity so fast you may “lose the ship.” Don’t hang in too long trying to battle a blaze that is clearly getting away from you, something akin to a fighter pilot of old hanging on too long in the burning cockpit, believing erroneously that he can ride out the damage.

When the can starts to sputter if the fire is not out or very nearly so, GET OUT and GET CLEAR!

Storing Fire Extinguishers

When keeping fire extinguishers around your home, you will ideally want two, perhaps more for a larger home. You will want to keep one extinguisher in the kitchen, a common starting point for house fires thanks to stove burners, small appliances and the like, and one in the master bedroom, to enable you a chance to react to a fire that starts at night while you are in bed.

Placement is important: do not keep the extinguisher near the most likely causes of fire! This seems counterintuitive to a quick response, but the reality is that a fire that brews up quickly may keep you from accessing the extinguisher location at all. So this means it should not be kept near outlets, near, under or over the kitchen oven and stove, etc.

It is too common an occurrence to omit special mention: there are plenty of incidents where well-meaning and proactive home or business owners placed their fire extinguishers too close to the most likely source of a fire, only for that fire to occur, and then rapidly overtake the location of the extinguisher.

This means you’d have a poor choice to make in the same situation: either abandon ship without attempting to control the fire or risk getting singed or lit up in an attempt to retrieve your fire extinguisher. Neither is ideal. Give the placement and access of your extinguisher much careful thought so you will be assured of the quickest and surest possible access.

Also do not bury your extinguisher in a drawer or cabinet. If there is ever a tool you’ll need to draw quickly when the time comes, it is a fire extinguisher. Instead, place it in an easy to access place and keep the area around it clear.

What About Car Storage?

***Disclaimer: You should always follow the manufacturer’s instructions and specifications for your fire extinguisher specifying safe storage and handling procedures.***

Fire extinguishers are pressure vessels, and when handling and storing pressure vessels you must always be cautious of allowing too much pressure to build up, lest you damage the valve or even incur an unexpected spontaneous release of pressure, which in the case of an extinguisher will create an enormous mess and render the extinguisher inoperable.

Keeping an extinguisher in your vehicle is a good idea for dealing with vehicle fires, but savvy preppers will think ahead to the risks from overheating a pressurized can of chemical in a broiling trunk when the car is left out in the summer.

It is a reasonable concern, and if you can to check the specs on an average fire extinguisher, you’ll see them typically rated for temperatures between -40° and 120° F. Most of us know your average internal temperature of a car in Florida will skyrocket past that.

So what do you do? Well, I say the proof is in the pudding: fleets of police cruisers and commercial trucks have fire extinguishers mounted in them, and hearing of an inadvertent discharge is a rarity. Anecdotal accounts suggest that those who have to call on their vehicle mounted extinguisher experienced no problems so long as they had it serviced according to manufacturer specifications.

On the offhand chance that your fire extinguisher does overheat and “pop”, you will be dealing not with a blast, but with only a sudden release of the contents; fire extinguishers, like most quality made pressure vessels, have safety release valves.

So carry you vehicle extinguisher with confidence, even if you live in an extremely hot area. The other concern for keeping an extinguisher in the vehicle is physical security. If kept in the passenger cabin loose, the dense metal can of a fire extinguisher will become a dangerous missile in a crash. If kept in the trunk, it will not be a danger but will be slower to access.

Whichever location you decide to keep it, install an appropriate mounting bracket and keep it clamped down.


Below are some additional tips to help you get the most from your extinguisher.

  • Read the manual! The manual that comes with your fire extinguisher will contain important facts like its range, average duration, service schedule and more.
  • Buy an extra unit to practice with. If you can safely try your extinguisher out on a practice fire, you’ll be far more prepared to handle a real one. If you cannot, then at least test your practice extinguisher’s range, pattern and controls at a suitable location.
  • Keep your range if you can do so safely. Most extinguishers will work best with a “sweet spot” not too close or too far from the fire. Again consult the manual.
  • Consider weight: An extra large, beefy fire extinguisher is just the thing to put out a modest blaze, but keep in mind it can be difficult or even impossible for some people to handle depending on their strength and any ailments they may have. You might be better off stepping down a size and getting multiples if you live with others who may not be able to handle a large extinguisher..


Structure and vehicle fires are deadly, common, and occur with speed. Your best chance of neutralizing one before they grow out of control is a proper fire extinguisher. Knowing what type to buy and how best to employ it could spell the difference between damage or death and destruction.

fire extinguisher

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1 thought on “How to Use a Fire Extinguisher”

  1. Good article and a good reminder that it takes more than lots of food and ammo to be prepared. I’ve been involved in the fire service since 93, and I have a few small things to add. I believe you have a typo in your description of a class C extinguisher. It should read a class C agent won’t conduct electricity. That’s all the class C means. Also class C fires are only class C while they are energized. For example; if you have a space heater on fire, and you unplug it, you now have a class A fire. Also, I feel any conversation on fire extinguishment by the general public needs to include a mention of smoke detectors. Your best opportunity to put it out safely, is to catch it while it’s small. A rule of thumb is a house fire doubles in size every minute. Smoke detectors greatly increase the likelihood that you will catch it early on. Thanks again for a good read.


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