Lesson 1: How fire starts and how it stops
Every fire needs three things at the same time: fuel, heat and oxygen. Take away any one of them and the fire goes out. This idea is called the fire triangle.
The fire triangle: a fire needs heat, fuel and oxygen together.
- Heat, such as a flame, spark or hot surface.
- Fuel, anything that can burn, such as wood, paper or a flammable liquid.
- Oxygen from the air.
Fire extinguishers work by attacking one side of the triangle:
- Water cools the burning material (takes away heat).
- Carbon dioxide (CO2) smothers the fire by pushing away the oxygen.
- Dry chemical and wet chemical agents coat the fuel and stop the burning.
Lesson 2: Preventing fires on your patrol
Most fires can be prevented. A guard on patrol is in a good position to notice hazards before they turn into fires. Each building's fire safety plan includes the control of fire hazards, so report what you find.
Fire hazard checklist
- Rubbish, cardboard or pallets near heaters, furnaces or lights
- Flammable liquids left open or stored in a hot place
- Overloaded power bars, damaged cords, or extension cords used as permanent wiring
- Smoking in no-smoking areas or near flammable materials
- Fire doors wedged open, and exits or corridors blocked
- Extinguishers missing, blocked or damaged
Flammable liquids should be kept in a cool, well-ventilated place in proper flammable storage equipment. Avoid storing large amounts, and avoid storing them in basements.
If you can fix a simple hazard safely and your post orders allow it, such as closing a fire door or moving a box away from a heater, do it and note it. For anything bigger, such as damaged wiring or leaking fuel, keep people away and report it to your supervisor or the building contact right away.
Lesson 3: Classes of fire
Fires are grouped into classes by what is burning. The class tells you which extinguisher is safe to use.
| Class | What is burning | Examples |
|---|---|---|
| A | Ordinary combustibles | Paper, wood, cloth, rubber, many plastics |
| B | Flammable liquids and gases | Gasoline, oil, paint, lacquer, propane |
| C | Energized electrical equipment | Computers, panels, motors that are plugged in |
| D | Combustible metals | Magnesium, titanium, sodium, potassium |
| K | Cooking oils and fats | Deep fryers and cooking appliances |
Each extinguisher has a label that shows which classes it is made for. Read the label before you use it. Using the wrong one can make the fire worse or put you in danger.
Lesson 4: Types of extinguishers
| Type | Use on | Do not use on / cautions |
|---|---|---|
| Water | Class A | Never on electrical, flammable liquid or cooking oil fires |
| Carbon dioxide (CO2) | Class B and C | Not for Class A; short range; in small closed rooms it can make breathing hard |
| Dry chemical | Class B and C, and some types also A (often marked ABC) | Leaves a powder residue that can damage electrical equipment |
| Wet chemical | Class K (cooking oils) | Made for kitchens; helps stop the oil from re-igniting |
| Class D agent | Combustible metals | Only for special sites that handle these metals |
Water can carry electricity back to you, so it must never be used on a live electrical fire. CO2 leaves no mess, but it does not cool deep-seated Class A fires well and it can push oxygen out of a small room.
Lesson 5: Deciding whether to fight a fire
Your first job is to keep people safe, including yourself. An extinguisher is only for small fires that are just starting.
Do NOT fight the fire if
- You do not know what is burning
- You do not know which extinguisher to use, or how to use it
- The fire is spreading beyond where it started
- Smoke is filling the room or your exit could be cut off
- Your instincts tell you to get out
If you cannot safely put the fire out: pull the fire alarm, evacuate and call the fire department. Close doors behind you to slow the fire.
Lesson 6: Using an extinguisher and checking it
Remember PASS:
- Pull the pin.
- Aim the nozzle low, at the base of the fire.
- Squeeze the handle.
- Sweep from side to side until the fire is out.
- Keep the fire in front of you and your exit behind you.
- Sweep a floor fire from the edges inward. Sweep a wall fire from the bottom up.
- Never walk away from a fire that looks out. It can reignite.
- Report any extinguisher you used, even a little, so it can be recharged.
Inspection on patrol
Portable extinguishers should get a visual inspection every month and be serviced at least once a year, or sooner if the monthly check finds a problem. Your site may ask you to help with monthly checks.
- Is it in its place, visible and not blocked?
- Is the pin and tamper seal in place?
- Is the pressure gauge, if it has one, in the operating range?
- Is there any damage, rust that causes pitting, or fire damage?
- Is the inspection tag present and up to date?
An extinguisher with damaged threads, pitting corrosion or fire damage must be taken out of service. Report it right away.