FIRE PREVENTION
Understanding Its Causes
THE FIRE Tetrahedron
For a fire to start four conditions must be met at the same time:
THE FIRE Tetrahedron
Fuels are materials that burn
The higher the temperature, the easier and quicker they burn
Common fuels include:
-- Solvents such as acetone, alcohols, and toluene
-- Gases such as acetylene and propane
-- Solids such as wood and paper
Fire Tetrahedron
Oxidizers: Oxygen or other substances capable of releasing oxygen to a fire
Common oxidizers include:
acids, especially nitric and perchloric acids
chlorine dioxide
Others such as potassium permanganate and potassium chlorate
THE FIRE TRIANGLE
An ignition source can be:
A Spark
Static electricity
Arcs from electrical equipment, faulty or otherwise
A lit cigarette
A hot light bulb
Fire Tetrahedron
Fire prevention consists of making sure that the four legs of the fire triangle never meet
FIRE PROPAGATION
Recent studies indicate that the spread or propagation of a fire is also dependent on a fourth factor - the chemical chain reactions that can occur as a result of heat produced by the fire.
FLAMABLE CONDITIONS
A fire will not always start when the legs of the fire triangle meet, unless all three elements are present in the required amounts
For example, vapors from a flammable liquid must be mixed with a certain amount of air in order to ignite and propagate a flame
FLAMMABLE RANGE
Lower Flammable Limit: The lowest concentration at which a fuel/air mixture will burn. Below this there is too little fuel (the mixture is too lean)
Upper Flammable Limit: The highest concentration at which a fuel/air mixture will burn. Above this there is not enough oxygen (the mixture is too rich)
FLASH POINT
The lowest temperature at which sufficient vapors form above the liquid to produce an ignitable mixture with air
FLAMMABILITY RANGE
The Department of Transportation classifies liquids for transportation regulation purposes
Flammables: All liquids with a flash point below 100 degrees Fahrenheit
Combustibles: All liquids with a flash point above 100 degrees Fahrenheit
FLAMMABLE GASES & SOLIDS
Gas cylinders such as acetylene welding gas need to be properly stored and used
Solids such as paper, wood, and cloth need to be treated as potential fuels
Rags or paper soaked with flammable liquids need to properly handled and disposed
Metals that burn (pyrophorics) are especially dangerous
STORAGE & HANDLING
Since it is impossible to eliminate oxygen from the fire triangle, fire prevention depends on trying to:
Eliminate sources of ignition
Restrict the amount of flammable and combustible liquids
STORAGE & HANDLING
Eliminate sources of ignition
Choose the least hazardous materials possible
Reduce the amounts stored to a minimum
Use safe storage procedures and containers
Ensure containers are properly labeled
CONTAINER LABELING
Flammable liquids should have a label such as this:
DANGER
FLAMMABLE
KEEP AWAY FROM HEAT, SPARKS & OPEN FLAMES
KEEP CLOSED WHEN NOT IN USE
NFPA LABELING SYSTEM
MATERIAL SAFETY DATA SHEETS (MSDS)
Information regarding fire prevention and fire extinguishing
Safe storage and handling procedures
Spill clean-up procedures
Proper labeling
Use to compare products for hazards such as flash point and flammability range
STORAGE AMOUNTS
Local and state fire codes limit the amounts of flammable and combustible liquids that can be stored in various locations
CHECK WITH YOUR LOCAL FIRE DEPARTMENT
STORAGE AREAS
Best location to store large amounts of flammable and combustible liquids is a separate outside building
If this is not possible, then a suitable flammable storage cabinet or inside storage room should be built
FLAMMABLE STOREAGE CABINETS
Built to meet OSHA and NFPA standards
Labeled in large letters:
FLAMMABLE-- KEEP FIRE AWAY
Maximum of 120 gallons of Class I, II, and III A liquids (60 gallons of Classes I and II)
Maximum of three cabinets may be located in a given fire area
STORAGE CONTAINERS
Quantities of flammable liquids exceeding one pint should be stored in approved portable safety cans
In instructional laboratories the largest container size for flammable liquids is one gallon (or a two gallon safety can)
STORAGE DRUMS
55 gallon drums should only be stored in a separate storage area away from heat and sunlight.
The maximum size of drum that should be stored indoors is 5 gallons
INSIDE STORAGE ROOMS
Requirements found in NFPA 30 (Flammable & Combustible Liquids Code)
Fire resistance rating of 2 hours for walls, floor, and ceiling
Class B fire doors
Automatic fire protection systems
Mechanical ventilation depending on the amount stored
Class I-Division 2 electrical wiring and fixtures
DISPENSING
When dispensing from drums, use approved transfer pumps or drum faucets
When pouring flammable liquids from a drum to a metal container, ground the drum and bond the metal container to the drum to prevent the build-up of any static charge
SPILLS AND LEAKS
Spills must be quickly and safely cleaned up
to prevent flammable vapors from igniting
A sufficient quantity of absorbent material should be kept on hand
Treat spill clean-up materials as flammable and dispose of separately from the regular trash
Large spills of flammable liquids (more than one quart) need special cleanup procedures
FIRE FIGHTING
Four Basic Types of Fires
Class A -- Common Solids
Class B -- Flammable Liquids
Class C -- Electrical Equipment
Class D -- Burning Metals
FIRE EXTINGUISHERS
Class A Types -- Water based for areas containing ordinary combustibles
Class ABC Multipurpose Dry Chemical -- Displaces oxygen and smothers the flame
Class ABC Halon 1211 -- Inhibits chain reactions of a fire
Class BC -- Carbon Dioxide displaces air and cuts off the oxygen supply
Automatic Sprinkler Systems
Water -- Sprays a mist when activated by the heat of a fire
Halon -- Sprays a halogenated chemical onto the fire. Halons decompose to toxic gases when heated. Use must be carefully planned.
OSHA REQUIRED PROCEDURES FOR FIGHTING FIRES
OSHA regulations allow for three situations:
Total evacuation in case of fire alarm
Partial evacuation with some employees allowed to use fire extinguishers
All employees allowed to use fire extinguishers
OSHA specifies training requirements if any employees are allowed to use fire extinguishers
USING FIRE EXTINGUISHERS
If you think you can handle the fire, sound the fire alarm to set the emergency plan in operation
Grab the closet fire extinguisher that conforms to the type of fire
Activate the fire extinguisher and follow the directions for use
If at any time you feel overwhelmed, or the extinguisher charge runs out, leave the area and wait for the professional fire fighters
INTEGRITY OF EQUIPMENT
Fire fighting equipment must be well maintained and checked periodically for pressure and integrity
Fire extinguishers must be placed prominently according to OSHA regulations
Fire suppression equipment, such as sprinkler systems, must also meet the appropriate OSHA and NFPA standards
REMEMBER !
Fire Prevention Is Everyone’s Responsibility
