Fire Safety

How Fires Start
Fire is a chemical reaction involving rapid oxidation or burning of a fuel. It needs three elements to occur:

• FUEL - Fuel can be any combustible material - solid, liquid or gas. Most solids and liquids become a vapor or gas before they will burn
• OXYGEN - The air we breathe is about 21% oxygen. Fire only needs an atmosphere with at least 16% oxygen
• HEAT - Heat is the energy necessary to increase the temperature of the fuel to a point where sufficient vapors are given off for ignition to occur.

Chemical Reaction
A chain reaction can occur when the three elements of fire are present in the proper conditions and proportions. Fire occurs when this rapid oxidation or burning takes place. Take any of these factors away and the fire cannot occur or will be extinguished if it was already burning.

How Fires are classified
CLASS A
Ordinary combustibles or fibrous material, such as wood, paper, cloth, rubber and some plastics.

CLASS B
Flammable or combustible liquids such as gasoline, kerosene, paint, paint thinners and propane.

CLASS C
Energized eletrical equipment, such as appliances, switches, panel boxes and power tools.

CLASS D
Metals such as titanium, magnesium and sodium. These metals burn without the presence of oxygen.

Generally, you can tell with a glance which type of extinguisher is hanging on the wall just by looking at its shape. Check the labels of the extinguishers in your area and note the color and shape/size of the extinguisher. This may help if someone runs in to help you fight a fire with the WRONG extinguisher (i.e. water on an electrical fire) - you can STOP them before they are injured or make matters worse!

ABC-rated multipurpose dry powder extinguishers are the most common, particularly in the corridors of commercial and academic buildings. They are almost always RED in color and have either a long narrow hose or no hose (just a short nozzle). These extinguishers are very light (5-25lbs total weight). Halon extinguishers look virtually identical to ABC multipurpose dry chemical extinguishers.

Water extinguishers are not often used in a commercial setting and are usually SILVER (chrome metal) in color, have a flat bottom, have a long narrow hose and are quite large (2 1/2 gallons). Foam extinguishers look similar and the type without gauges have a handle inset in the flat bottom (you turn the extinguisher upside down to start it and use it).

CO2 (carbon dioxide) extinguishers are generally red (often yellow around aircraft or on military sites), have a LARGE "tapered" nozzle (horn) and are VERY HEAVY (15-85lbs). Some CO2 extinguishers for aircraft hangers or special industrial use are so large as to require roll-around carts to move them. These are all high-pressure cylinders.

Care should be used NOT TO DROP a CO2 cylinder; if it is damaged, it can punch a hole through the nearest wall... or worse. The containers are quite sturdy, but do not abuse them. CO2 cylinders do not have a pressure gauge - they must be weighed to determine the amount of contents.

How to extinguish small fires:
Class A - Extinguish ordinary combustibles by cooling the material below its ignition temperature and soaking the fibers to prevent re-ignition. Use pressurized water, foam or multi-purpose (ABC-rated) dry chemical extinguishers. DO NOT USE carbon dioxide or ordinary (BC-rated) dry chemical extinguishers on Class A fires.

Class B - Extinguish flammable liquids, greases, or gases by removing the oxygen, preventing the vapors from reaching the ignition source, or by inhibiting the chemical chain reaction. Foam, carbon dioxide, ordinary (BC-rated) dry chemical, multi-purpose dry chemical, and halon extinguishers may be used to fight Class B fires.

Class C - Extinguish energized electrical equipment by using an extinguishing agent that is not capable of conducting electrical currents. Carbon dioxide, ordinary (BC-rated) dry chemical, multi-purpose dry chemical and halon* fire extinguishers may be used to fight Class C fires. DO NOT USE water extinguishers on energized electrical equipment.

*Even though halon is widely used, EPA legislation is requiring that it be phased out of use in favor of agents less harmful to the environment.

Class D - Extinguish combustible metals such as magnesium, titanium, potassium, and sodium with dry powder extinguishing agents specially designated for the material involved. In most cases, they absorb the heat from the material, cooling it below its ignition temperature.

How to use a portable fire extinguisher
 

Remember the acronym, "P.A.S.S."
P	Pull the Pin
A	AIM extinguisher nozzle at the base of the flames
S	Squeeze trigger while holding the extinguisher upright
S	Sweep the extinguisher from side to side, covering the area of the fire with the extinguishing agent.

Remember - leave the area IMMEDIATELY if...

• your path of escape is threatened.
• the extinguisher runs out of agent.
• the extinguisher proves to be ineffective.
• you will no longer be able to safely fight the fire.

When NOT to fight a fire:

• If the fire is spreading beyond the spot where it started.
• If you can't fight the fire with your back to an escape exit.
• If the fire can block your only escape.

What to do if someone catches on fire:
STOP - where you are
DROP - to the floor
ROLL - around on the floor
This will smother the flames, possibly saving your life or the life of someone else. Just remember "STOP, DROP and ROLL."

If a another person catches on fire, smother flames by grabbing a blanket or rug and wrapping them up in it. That could save them from serious burns or even death. NEVER RUN if you are on fire... this will feed oxygen to the fire.