Workplace Safety 3220 Chapter 3.2 Fire Protection

3.2 Fire Protection In this chapter you will understand: Why fires occur, and How to properly apply the procedures used to Prevent, Detect and Extinguish fires

3.2 Fire Protection Work-related fires have killed hundreds of people in this country and injured thousands of others. Many fires are caused by the unsafe acts of people through carelessness and a lack of knowledge. What they all have in common is that they are Preventable. Fire prevention is Everyone's Responsibility.

The Chemistry of Fire For a fire to occur, 4 components are necessary: Fuel Oxygen Heat Chemical Chain Reaction

Common Causes of Fire Smokers Materials Cigarettes Matches Open Flame Electrical Fuses Short Circuits Overlaoded Circuits Loose Connections Misuse of Flammable Liquids Fat Fires Oily Rags

Explosions An explosion is A very rapid, contained fire occurring when the gases produced by the fire exceed the pressure capacity of the container. A simple example is a firecracker: 1.The fuse burns into the centre of the firecracker. 2.The powder inside ignites and burns very rapidly, producing gas. 3.The paper wrapper cannot withstand the pressure and blows apart.

Explosions

Controlling Fires Knowing how and why fire burns suggests ways to control it. Fire can be controlled in the following ways: By cooling the burning materials By removing oxygen By removing fuel These methods interrupt the chemical chain reaction.

Heat Transfer Heat always moves from higher temperatures to lower temperatures. Heat from a fire is transferred to other objects in 3 ways: Conduction: direct heat transfer through solids and liquids in contact with each other. Radiation: electromagnetic wave transfer of heat to a solid. Eg. Heat and light from the Sun Convection: heat transfer through the movement of hot gases.

Types of Heat Transfer

Spontaneous Combustion This can occur when organic compounds decompose and release flammable gas. This leads to a buildup of heat and can result in a fire. In nature, such as in forests and swamps, gas and heat are vented naturally and fires are rare. If oily rags are stored in a closed container, heat buildup can cause the oil to vapourize. This creates a potentially dangerous hazard. Proper containers are required.

Classification of Fires Fires are classified according to the types of materials being burned.

Class A Fire Ordinary materials Wood, paper, garbage Class A fires are extinguished by the quenching and cooling effects of water.

Class B Fire Flammable or combustible gases and liquids. Gasoline, kerosene, propane, grease, paint thinner, paint, oil. Water will spread the fire. Use dry chemicals, CO 2, or foam.

Class C Fires Energized electrical equipment. Appliances, power tools, switches. Do not use foam or water (they conduct electricity). Use dry chemicals or CO 2.

Class D Fires Combustible metals. Titanium, magnesium, sodium, potassium, phosphorous*. Do Not use normal extinguishing agents of Class D fires. It can make them more intense. Use only specialized techniques, agents and equipment.

Fire Prevention

Practise Good Housekeeping: Keep work area free of clutter Clean flammable dust regularly (sawdust) Wipe up spills of flammable liquids Keep fire exits and exit routes clear Never use alcohol or gasoline as a cleaning agent Store flammable waste in proper containers Store flammable liquids properly Extinguish cigarettes in proper containers Obey all “No Smoking” signs

Fire Prevention Avoid Electrical Hazards Don't overload circuits Discard frayed or worn cords Check for problems with electrical equipment Overheating Faulty switches Exposed wires Never use a tool or extension cord if the grounding plug has been removed.

Fire Prevention Be careful handling flammable, combustible, and explosive materials Flammable – materials that catch fire and burn easily and give off intense heat Liquids – gasoline, acetone Solids – phosphorous, magnesium, sodium Gases – propane, acetylene, hydrogen

Fire Prevention Combustible – materials that will burn under ordinary circumstances because of an outside source paper, wood, cloth

Fire Prevention Explosive - materials such as dynamite, nitroglycerin, blasting caps, metal powders, plastic powders, even dust.

Fire Prevention Keep flammable, combustible, and explosive material away from sources of heat or friction. Never refuel a hot or running engine Clean up spills immediately Look out for empty containers that once held flammable materials Flammable, combustible, and explosive materials must be properly labelled

Fire Prevention Minimize the potential for a dust explosion Can occur when a spark comes in contact with sawdust, mill dust, or other finely divided particles.

Fire Prevention Be aware of possible ignition sources Flame Cigarettes Static electricity Sparks Welding Furnaces Hot ash Heating elements Electrical switches

Responding to a Fire Know the locations of fire alarms Know the locations and operation of fire extinguishers Be aware of the nearest fire exits Know evacuation procedures Know where to gather after evacuation Know the company's procedure for reporting a fire

Escape and Muster Plans

Industrial Fires Try to eliminate the causes of fires: Use only approved equipment Establish Safe Work Practises Enforce good housekeeping procedures Train workers to spot hazardous conditions and report them immediately.

Industrial Fires Develop Fire Protection Programs Design buildings with fire protection in mind Enforce regular inspections Train employees in detection, alarms, evacuation, preventing, confining, and extinguishing a fire.

Fire Detection Fire detection devices include: Human observers Automatic sprinklers Smoke, flame, heat, CO 2, and CO detectors

Fire Detection The 2 main tasks of fire detection are: To give an early warning to allow building occupants to escape To give an early warning to fire-fighting teams to prevent or minimize losses

Fire Detection Building should be equipped with fire detection systems that do 2 important things: Communicate to all where the fire is located Summon appropriate fire-fighting units. When an alarm is sounded, all employees must know what the sound means. A building can have different alarms for different emergencies