The physics of fire are downright daunting when it comes to how fast a bit of flame can erupt into a roaring fire. Spending a few minutes now to learn how to use a fire extinguisher could one day save your home – or your life.

Install a fire extinguisher on the wall in buiding
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How to Use a Fire Extinguisher

It's important to note that fire extinguishers handle different classes of fires, and you'll need to see what class of fire your extinguisher is meant for. If your extinguisher isn't graded for the fire you have, then leave and call the fire department. The most common fire extinguisher is meant for fires caused by burning paper, wood, cloth, some rubbers and plastics, which is a "class A" fire. If you have a grease fire, that's a "class K" fire and requires a different extinguisher (or a big box of baking soda). If you've got the right extinguisher for the fire you're facing, make sure it's a small enough fire – just a few feet in size – that you can effectively fight it.

When Not to Use a Fire Extinguisher

If a fire is already so large – more than 10 feet in size – that you can't get near enough to fight it, then evacuate. Pull the fire alarm if there's one in your building, and call 911 or the fire department immediately.

A quick-growing fire can be life-threatening. If, in the time you race to grab the extinguisher, it grows considerably, then get out and call the firefighters. If smoke is so excessive that you can't see or breathe, evacuate. If fire threatens to get between you and the only exit, then exit before you lose that opportunity.

Fires take lives every year, so don't take the chance with fires that could be too large to fight. Luckily, most fires start out fightable, and good extinguisher know-how can help you save the day.

Maintaining a Fire Extinguisher

The worst-case scenario is to need a fire extinguisher only to have it fail because critical maintenance wasn't kept up. Extinguisher contents are pressurized, and they can lose their charge over time, especially if seals weaken.

Check your extinguisher's label for last inspection date. More than five years old puts it in a cautionary category. Does it have a pressure gauge? Great! If it's in the green, you can rest easy as it should be fine for fighting fires. If it just lists psi, then 100 to 175 is the ideal range. Keep an eye on this gauge monthly to ensure the charge stays strong.

If there is no gauge, it's strongly recommended you do a web search for "fire extinguisher services" or "specialist" in your area. For $15 or $20, you can have the extinguisher tested and even recharged. A new extinguisher will likely cost over $100, so it's money well spent.

Where to Put a Fire Extinguisher

We've all seen extinguishers sitting on the floor or under the sink, which is not a good plan. If it should topple or dent, it can lose its charge and won't work. If dust, flour or other residue should gum up the works, the extinguisher may fail in your time of need.

Instead, the U.S. Occupational Safety and Health Administration (OSHA) mandates the clearance needed around workspace extinguishers. They recommend wall-mounting where direct sunlight won't hit the unit. There should also be a 3-foot radius in front of and around the unit, and it should never be mounted near a heat source or stove.

OSHA recommends mounting at 4 to 5 feet high in spots like hallways, where it can't be banged or jostled by passers-by or heavy equipment. Obviously, you don't need to follow workplace regulations at home, but it's certainly best practice and won't steer you wrong.

Know the Method for Firefighting

Acronyms make remembering steps easy. For using a fire extinguisher, think P.A.S.S. – "Pull, Aim, Squeeze, Sweep."

Your fire extinguisher has only 10 seconds of compression, on average, so that's all the time you get to stop this fire. It's important to be prepared for each step and to never touch the top lever until you're ready to fight the fire.

Fighting Fire With an Extinguisher

First, locate the pin at the top where the lever meets the handle. This normally prevents you from accidentally discharging the canister, but now that's exactly what you're going to do.

Get ready to pull the pin out, but keep your hand off the top lever so you don't accidentally break the seal to start discharging the unit.

Get positioned. Stand 6 feet or more away from the fire. Take a strong stance so the discharging extinguisher won't unsettle you.

Now, pull the pin out. Aim the nozzle at the base of the fire, but never aim at the flames themselves. This does not affect the fire but aiming at the bottom will.

During your 10 seconds of spraying time, sweep the extinguisher side to side to spray the entire base of the fire. If the flames are dying down as you spray, close in on the fire as you finish spraying.

When the canister empties, is the fire out? As the saying goes, where there's smoke, there's fire. If you see smoke or smoldering, call the fire department if you think it can reignite.

In the following days, have your cannister checked by a professional and recharged. They can make sure no gaskets or seals were affected in your firefighting.

With the P.A.S.S. method and a well-maintained fire extinguisher, you're well-positioned to save the day should a fire erupt.