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Fire Extinguisher PASS Method and Fire Classes

PASS stands for Pull, Aim, Squeeze, Sweep. It's the technique OSHA's fire extinguisher eTool describes for most portable extinguishers. Before you use one, you also need to know whether the fire is small enough to fight and whether your extinguisher is the right type. Fires are grouped into classes by what is burning, and extinguishers are labeled for the classes they can put out. This guide covers all three, plus OSHA's training rule for employers that provide extinguishers.

Updated October 14, 2026 · Checked against the official sources listed at the end

The PASS method

OSHA's eTool says most fire extinguishers operate using the P.A.S.S. technique:

Pull the pin. This also breaks the tamper seal.
Aim low, pointing the nozzle, horn or hose at the base of the fire. Don't touch the plastic discharge horn on a CO2 extinguisher; it gets very cold and may damage skin.
Squeeze the handle to release the extinguishing agent.
Sweep from side to side at the base of the fire until it appears to be out. Watch the area. If the fire re-ignites, repeat aim, squeeze and sweep.

Before you use an extinguisher

OSHA's eTool lists steps for responding to a fire in its early stage:

Sound the fire alarm and call the fire department, if appropriate.
Identify a safe evacuation path before approaching the fire. Don't let the fire, heat or smoke come between you and your way out.
Select the right type of extinguisher.
Discharge it within its effective range using PASS.
Back away from an extinguished fire in case it flames up again.
Evacuate immediately if the extinguisher is empty and the fire is not out, or if the fire grows beyond its early stage.

What "incipient stage" means

OSHA's rules talk about incipient stage fires. An incipient stage fire is one in its initial or beginning stage that can be controlled or put out with portable extinguishers or small hose systems without protective clothing or breathing apparatus (29 CFR 1910.155(c)). Past that point, a portable extinguisher is the wrong tool. Get out.

Fire classes

OSHA's definitions (1910.155(c)) and its eTool group fires by what is burning:

Class A: ordinary combustible materials such as paper, wood, cloth, and some rubber and plastic materials.
Class B: flammable or combustible liquids, flammable gases, greases and similar materials. The eTool's examples include oils, gasoline, some paints, lacquers and solvents.
Class C: energized electrical equipment, where the extinguishing agent must not conduct electricity. Think wiring, fuse boxes and computers.
Class D: combustible metals such as magnesium, titanium, zirconium, sodium, lithium and potassium. These need special extinguishers labeled D.
Class K: kitchen fires involving combustible cooking fluids such as oils and fats. The eTool warns that other extinguishers may not put out a fire in a deep fat fryer.

Common extinguisher types

Water (air-pressurized water): for Class A fires only. Never use water on flammable liquid fires, where it can spread the fire, or on electrical fires, where it can cause electrocution.
CO2 (carbon dioxide): for Class B and C fires. OSHA says CO2 isn't recommended for Class A fires because they may smolder and re-ignite. Don't use it in a confined space with people present unless they have proper respiratory protection.
Multi-purpose dry chemical: suitable for Class A, B and C fires.
Class D and Class K: special extinguishers for metal and kitchen fires.

How to read an extinguisher label

OSHA requires portable extinguishers to be approved by a nationally recognized testing laboratory (1910.157(c)(2)). Approved extinguishers carry a rating such as 1-A:10-BC.

OSHA's eTool explains the parts. The letters show which classes of fire the extinguisher is approved for. The number before the A shows its water equivalent: each unit equals 1.25 gallons of water, so a 4-A rating equals five gallons. The number before the B is the area in square feet of a Class B fire a non-expert user should be able to put out, so 10-B means about 10 square feet.

OSHA's training rule for employers

Where an employer provides portable fire extinguishers for employee use, it must provide an educational program on the general principles of extinguisher use and the hazards of fighting a fire in its early stage (1910.157(g)(1)). The education is due upon initial employment and at least annually after that (1910.157(g)(2)).

Employees designated to use firefighting equipment under an emergency action plan need training on the appropriate equipment, when first assigned and at least annually (1910.157(g)(3)-(4)).

Employers must also have extinguishers visually inspected monthly and given an annual maintenance check, with the maintenance date recorded (1910.157(e)). Our workplace fire safety training guide covers the exemptions and emergency action plans.

Pact's Workplace Fire Safety course

Pact sells the Workplace Fire Safety course for $24.95. Workplace Fire Safety is an online certification course from ProTrainings. Confirm with your program or clinical site that this course meets its requirements before you enroll. ProTrainings makes and runs the course, and Pact sells it and handles your order.

OSHA says it does not approve, certify, or endorse individual trainers or training programs. A course can teach PASS and fire classes. It can't show your workers where your extinguishers and exits are. That part is the employer's job. Buyers must be 18 or older, and all sales are final.

Common questions

What does PASS stand for?

Pull, Aim, Squeeze, Sweep. Pull the pin, aim low at the base of the fire, squeeze the handle, and sweep side to side.

What are the classes of fire?

Class A (ordinary combustibles), Class B (flammable liquids and gases), Class C (energized electrical equipment), Class D (combustible metals) and Class K (cooking oils and fats).

What does 1-A:10-BC mean on an extinguisher?

It is approved for Class A, B and C fires. The 1-A equals 1.25 gallons of water. The 10-B means a non-expert should be able to put out about 10 square feet of flammable liquid fire.

Is fire extinguisher training required every year?

Where an employer provides extinguishers for employee use, OSHA requires the educational program upon initial employment and at least annually after that (29 CFR 1910.157(g)(2)).

When should I not use a fire extinguisher?

When the fire is beyond its early stage, when your exit path could be blocked, when you don't have the right type of extinguisher, or when you have any doubt. OSHA's eTool says to evacuate immediately.