How to Choose The Best Extinguisher

When selecting the appropriate type of fire extinguisher, it is important to think about extinguishing agents. Each class of fire is best fought by a specific extinguishing agent.You will find a color-coded box on your fire extinguisher identifying which classes of fire it can be used for, and the type of fire extinguishing agent it contains.

The following is a list of commonly used fire extinguishing systems and their corresponding classes of fire. The classes are indicated in parentheses such as (A, B, C):

Multi-Purpose Dry Chemical (A, B, C)
A dry chemical agent called mono ammonium phosphate. The chemical is non-conductive and can be mildly corrosive if moisture is present. In order to avoid corrosion, it is necessary to scrub and thoroughly cleanup the contacted area once the fire is out. A dry chemical fire extinguisher is usually used in schools, general offices, hospitals, homes, etc.

Regular Dry Chemical (B, C)
A dry chemical agent called sodium bicarbonate. It is non-toxic, non-conductive and non-corrosive. It is easy to cleanup, requiring only vacuuming, sweeping or flushing with water. Extinguishers with sodium bicarbonate are usually used in residential kitchens, laboratories, garages, etc.

Carbon Dioxide (B, C)
Carbon dioxide removes oxygen to stop a fire but has limited range. It is environmentally friendly and leaves no residue, so cleanup is unnecessary. Extinguishers with carbon dioxide are usually used in contamination-sensitive places such as computer rooms, labs, food storage areas, processing plants, etc.

Halotron (A, B, C)
A vaporizing liquid that is ozone friendly and leaves no residue. Because it requires no cleanup, fire extinguishers with halotron are ideal for computer rooms, telecommunication areas, theaters, etc.

Foam (A, B)
Foam floats on flammable liquids to tame the fire and helps prevent reflashes. To cleanup the affected area, it must be washed away and left to evaporate. Fire extinguishers with foam are usually used in garages, homes, vehicles, workshops, etc.

Purple K Dry Chemical (B, C)
A dry chemical called potassium bicarbonate. It is non-conductive and non-corrosive. Clean up requires vacuuming, sweeping or flushing with water. Extinguishers with potassium bicarbonate are usually used in military facilities, oil companies, vehicles, etc.

Water (A)
The most common agent is water; however, it cannot be used for class B or C fires because it is conductive. Water-based fire extinguishers are usually used in stockrooms, schools, offices, etc.

* Dry chemicals, CO2 and halon can be used on Class A fires, but may not be effective on their own. They need to be supplemented with water.

Fire needs fuel, oxygen and heat in order to burn. In simple terms, fire extinguishers remove one of these elements by applying an agent that either cools the burning fuel, or removes or displaces the surrounding oxygen.

Fire extinguishers are filled with water or a smothering material, such as CO2. By pulling out the safety pin and depressing the lever at the top of the cylinder (the body of the extinguisher), this material is released by high amounts of pressure.

How it Works
At the top of the cylinder, there is a smaller cylinder filled with compressed gas. A release valve acts as a locking mechanism and prevents this gas from escaping. When you pull the safety pin and squeeze the lever, the lever pushes on an actuating rod which presses the valve down to open a passage to the nozzle. The compressed gas is released, applying a downward pressure on the fire-extinguishing material. This pushes the material out the nozzle with high amounts of pressure.

Although the temptation is to aim the extinguisher at the flames, the proper way to use the extinguisher is to aim it directly at the fuel.

Water Extinguishers
Water extinguishers are filled with regular tap water and pressurized with oxygen. The best way to remove heat is to dump water on the fire but, depending on the type of fire, this is not always the best option.

Dry Chemical Extinguishers
Dry chemical extinguishers are filled with either foam or powder, usually sodium bicarbonate (baking soda) or potassium bicarbonate, and pressurized with nitrogen. Baking soda is effective because it decomposes at 158 degrees Fahrenheit and releases carbon dioxide (which smothers oxygen) once it decomposes. Dry chemical extinguishers interrupt the chemical reaction of the fire by coating the fuel with a thin layer of powder or foam, separating the fuel from the surrounding oxygen.

Carbon Dioxide (CO2) extinguishers
CO2 extinguishers contain carbon dioxide, a non-flammable gas, and are highly pressurized. The pressure is so great that it is not uncommon for bits of dry ice to shoot out. CO2 is heavier than oxygen so these extinguishers work by displacing or taking away oxygen from the surrounding area. CO2 is also very cold so it also works by cooling the fuel.

 

 

All fires can be very dangerous and life-threatening. Your safety should always be your primary concern when attempting to fight a fire.

Before deciding to fight a fire, be certain that:

• The fire is small and not spreading. A fire can double in size within two or three minutes.
• You have the proper fire extinguisher for what is burning.
• The fire won't block your exit if you can't control it. A good way to ensure this is to keep the exit at your back.
• You know your fire extinguisher works. Inspect extinguishers once a month for dents, leaks or other signs of damage. Assure the pressure is at the recommended level. On extinguishers equipped with a gauge, the needle should be in the green zone - not too high and not too low.
• You know how to use your fire extinguisher. There's not enough time to read instructions when a fire occurs.

How to Fight a Fire Safely:

• Always stand with an exit at your back.
• Stand several feet away from the fire, moving closer once the fire starts to diminish.
• Use a sweeping motion and aim at the base of the fire.
• If possible, use a "buddy system" to have someone back you up or call for help if something goes wrong.
• Be sure to watch the area for awhile to ensure it doesn't re-ignite.

Never Fight A Fire If:

• The fire is spreading rapidly. Only use a fire extinguisher when the fire is in its early stages. If the fire is already spreading quickly, evacuate and call the fire department.
• You don't know what is burning. Unless you know what is burning, you won't know what type of fire extinguisher to use. Even if you have an ABC extinguisher, there could be something that will explode or produce highly toxic smoke.
• You don't have the proper fire extinguisher. The wrong type of extinguisher can be dangerous or life-threatening.
• There is too much smoke or you are at risk of inhaling smoke. Seven out of ten fire-related deaths occur from breathing poisonous gases produced by the fire.

Any sort of fire will produce some amount of carbon monoxide, the most deadly gas produced by a fire. Materials such as wool, silk, nylon and some plastics can produce other highly toxic gases such as carbon dioxide, hydrogen cyanide, or hydrogen chloride. Beware - all of these can be fatal.

Smoke inhallation or exposure to fire itself can be life threatening so get educated about the basics in CPR and burn treatment.