Fire Safety        

 

INTRODUCTION

Fire is the third leading cause of accidental deaths in the United States, yet most people ignore it. More than 150 workplace fires occur every day.
Note, you can ask your city fire department to teach this class if you have enough people attending it.

Do you know...



If you answered yes to all those questions, are you willing to take a quiz to prove it?


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 percent oxygen. fire only needs an atmosphere with at least 16 percent 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 one 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 electrical equipment, such as appliances, switches, panel boxes and power tools.
CLASS D
Certain combustible metals, such as magnesium, titanium, potassium and sodium. These metals burn at high temperatures and give off sufficient oxygen to support combustion. They may react violently with water or other chemicals, and must be handled with care.





HOW TO PREVENT FIRES

Class A Ordinary combustibles:
Keep storage and working areas free of trash Place oily rags in covered containers.




Class B Flammable liquids or gases:
Don't refuel gasoline-powered equipment in a confined space, especially in the presence of an open flame such as a furnace or water heater.

Don't refuel gasoline-powered equipment while it's hot.

Keep flammable liquids stored in tightly closed, self-closing, spill-proof containers. Pour from storage drums only what you'll need.

Store flammable liquids away from spark-producing sources.

Use flammable liquids only in well-ventilated areas.


Class C Electrical equipment:
Look for old wiring, worn insulation and broken electrical fittings. Report any hazardous condition to your supervisor.

Prevent motors from overheating by keeping them clean and in good working order. A spark from a rough-running motor can ignite the oil and dust in it.

Utility lights should always have some type of wire guard over them. Heat from an uncovered light bulb can easily ignite ordinary combustibles.

Don't misuse fuses. Never install a fuse rated higher than specified for the circuit.

Investigate any appliance or electrical equipment that smells strange. Unusual odors can be the first sign of fire.

Don't overload wall outlets. Two outlets should have no more than two plugs.


Class D Flammable metals:
Flammable metals such as magnesium and titanium generally take a very hot heat source to ignite; however, once ignited are difficult to extinguish as the buring reaction produces sufficient oxygen to support combusion, even under water.

In some cases, covering the burning metal with sand can help contain the heat and sparks from the reaction. Class D exinguishing agents are available (generally as a dry powder in a bucket or box) which can be quite effective, but these agents are rare on the campus.

If you are planning a research project using a large amount of flammable metals you should consider purchasing a five or ten pound container of Class-D extinguishing agent as a precaution.

Pure metals such as potassium and sodium react violently (even explosively) with water and some other chemicals, and must be handled with care. Generally these metals are stored in sealed containers in a non-reactive liquid to prevent decay (surface oxidation) from contact with moisture in the air.

White phosphorus is air-reactive and will burn/explode on contact with room air. It must be kept in a sealed container with a non-reactive solution to prevent contact with air.

All of these metals are not uncommon in labs on the OU campus, but are generally only found in small quantities and accidental fires/reactions can be controlled or avoided completely through knowledge of the properties of the metals and using good judgement and common sense.


WHEN NOT TO FIGHT A FIRE

Never 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
     
  • If you don't have adequate fire-fighting equipment



In any of these situations,

 

DON'T FIGHT THE FIRE YOURSELF.
CALL FOR HELP.




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 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 phasing it 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.

NOTE: Multipurpose (ABC-rated)chemical extinguishers leave a residue that can harm sensitive equipment, such as computers and other electronic equipment. Because of this, carbon dioxide or halon extinguishers are preferred in these instances because they leave very little residue.

ABC dry powder residue is mildly corrosive to many metals. For example, residue left over from the use of an ABC dry powder extinguisher in the same room with a piano can seriously corrode piano wires.

Carbon dioxide or halon extinguishers are provided for most labs and computer areas on campus.




WHAT TO DO IF SOMEONE CATCHES ON FIRE

If you should catch on fire:

STOP - where you are

DROP - to the floor

ROLL - around on the floor

This will smother the flames, possibly saving your life.

Just remember to STOP, DROP and ROLL.

If a co-worker 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.


SUMMARY

KNOWLEDGE - AWARENESS - PREPARATION

These are your keys to preventing and surviving fires wherever they occur.