Chapter 15: Fire Hazards and Life Safety

Flammable liquids have a flash point below...

99.8 degrees Fahrenheit (37.7C)

Exit discharge

Any part of the exit route that leads directly outside of the building or to an open space that has access to the outside

fire safety programs include (possible essay?)

Assessment planning awareness and prevention

Class D fires

Fires involving combustible metals such as magnesium, titanium, zirconium, sodium, and potassium.

OSHA 29 CFR 1910.134

Respiratory Protection

Conduction

The direct transfer of heat from one substance to another substance that it is touching. direct thermal energy transfer

Radiation

The transfer of energy (heat to solid) by electromagnetic waves

Class A fires

Usually involve wood, paper, cloth, or cardboard and typically happen in dry-storage areas, dining areas, garbage areas, and restrooms.

Fire (combustion)

a chemical reaction between oxygen and a combustible fuel

Carbon monoxide

a colorless, odorless toxic flammable gas formed by incomplete combustion of a fuel. Most fires lack oxygen and produce heavy amount of monoxide

Fire is a chain reaction. For combustion to continue there must be...

a constant source of fuel, oxygen, and heat

Exit routes

a continuous and unobstructed path of travel from any point within a workplace to a place of safety. three components: exit access, exit, and exit discharge (2 are generally required and must be unlocked from inside)

Hypergolic reaction

a violent reaction occurring when a fuel and oxidizer are mixed. The mixing of liquid hydrogen and liquid oxygen is also an example of this reaction.

Hot work

according to OSHA standards, any riveting, welding, flame cutting or other operation which produces sparks and/or fire. Programs should be in place for these jobs

Exit

any part of the exit route that provides a means of access to the exit discharge

Combustible liquids have a flash point

at or higher than flammable liquids

Almost everything in an industrial environment

can burn

The number one killer in fires

carbon monoxide

Smoke

combination of gases, air, and suspended particles

Explosive range (flammable range)

concentrations of a vapor or gas in the air that can ignite from a source

Fire hazards

conditions that favor fire development or growth

Heat transfer is accomplished by...

conduction radiation convection

Endothermic reaction

consumes more heat they they generate

Exothermic reaction

create heat

Photoelectric Fire sensors

detect changes in infrared energy that is radiated by smoke (often from smoke particles obscuring the photoelectric beam)

National Fire Protection Association (NFPA)

devised the NFPA 704 system for quick identification of hazards when presented substances burn used red (flammability), yellow (reactivity), white (special information), and blue (health) triangles that are used on product labels, shipping cartons, and building. ratings in each triangle go from 0 to 4 with 4 being the most severe hazard level

Permissible exposure limit

expressed in parts of vapor per million parts of contaminated air (important because many vapors present inhalation hazards as well as fire hazards)

Special category fires

extremely active oxidizers or mixtures, flammables containing oxygen, nitric acid...

Fire extinguisher systems

fire brigades standpipe and hose systems automatic sprinkler systems (fixed)

Products of combustion

gases, flame (light), heat and smoke

Heat always flows from

higher temperature to lower temperature

A major cause of industrial fires is

hot, poorly insulated machinery and processes

Spontaneous combustion

ignition of a substance (as oily rags) resulting from an internal oxidation process (rare)

The principle method of fire suppression..

is passive (the absence of sufficient heat)

By-products of combustion

light and smoke

During the combustion process

materials are broken down into basic elements. loose atoms form bonds with each other to create molecules of substances that were not originally present

Interior structural fire brigade

may fight any type of fire provided it has been issued the appropriate protective clothing and equipment

Performance based standard example

may specify that materials used have a one, two, or four hour fire resistance rating

The major cause of industrial fires is

mishandling flammable liquids and flammable gases

Synthetic polymers

often form deadly fumes when consumed by fire

Elements required to start and sustain fire

oxygen fuel heat

The trend in fire safety standards is toward _____ and away from ____

performance based standards Traditional specification based approach

Explosion

rapid, contained fire

A fire may be extinguished by

removing the fuel source, starving it of oxygen, or cooling it below the combustion point

Traditional specification based approach example

require that brick, concrete, or steel material to be used in a given type of building

OSHA regulations for fire brigades

scope prefire planning organizational statement physical capability training and education firefighting equipment protective clothing respiratory protective devices

Pyrophor hypergolic fuels

self-ignite in the presence of oxygen found at the normal atmospheric concentrations

Fuels occur as

solids, liquids, vapor, and gases

Ultraviolet detectors or infrared detectors

sound an alarm when the radiation from fire flames is detected

What is needed for a reaction to start?

source of ignition (spark or open flame) or a high enough temperature

Electrical lines and sources of heat are also

sources of ignition

OSHA standards for fire protection appear in

29 CFR 1910.156 (subpart L)

Most people die in fires due to

suffocation or breathing smoke and toxic fumes. Many fire extinguishers use carbon dioxide because of its ability to starve the fire of oxygen while simultaneously cooling the fire

Ignition temperature or combustion point

temperature at which a given fuel can burst into flames

The properties of the fuel directly correspond to

the best means of combatting the fire

Fire hazards typically involve...

the mishandling of fuel or heat

Lower flammable limit

the percentage of vapor in the air above which a fire cannot occur because there is insufficient fuel (the mixture is too lean)

Upper flammable limit

the percentage of vapor in the air above which there is insufficient air for a fire (the mixture is too rich)

Combustion

the process where fire converts fuel and oxygen into energy (usually in the form of heat)

In order for liquids and solids to burn

they have to be converted into a flammable vapor by heat

The best way to reduce fires is

to prevent them

Excess heat from a fire is...

transferred to surrounding objects which may ignite, explode, or decompose

Thermal expansion detectors

use a heat sensitive metal link that melts at a predetermined temperature to make contact and sound an alarm

Ionization or radiation sensors

use the tendency of a radioactive substance to ionize when exposed to smoke. the substance becomes electrically conductive with the smoke exposure and permits the alarm circuit to be completed

Incipient fire brigade

used to control only small fires. Requires no special clothing or equipment

If a flammable liquid is lighter than water

water cannot be used to put out the fire

Vapor density

weight of a vapor compared to air

Carbon dioxide is produced

when there is more oxygen than the fire needs. not toxic but can reduce concentration of oxygen in the air

OSHA fire prevention plans

Make a list of all fire hazards in the workplace. record the proper handling and storage procedures for all hazardous materials in the workplace. List potential ignition sources in the workplace and their means of control. record the type(s) of fire protection equipment needed to control all fire hazards in the workplace. Develop and record procedures to control flammable and combustible waste materials.

Fire Tetrahedron

Model of the four elements/conditions required to have a fire. The four sides of the tetrahedron represent fuel, heat, oxygen, and chemical chain reaction.

Auto ignition temperature

The lowest temperature at which a combustible material ignites in air without a spark, source of ignition, or flame.

Flash point

The lowest temperature to which a substance must be heated in order for the substance to give off vapors which will burn when exposed to a flame or ignition source.

Fire point

The minimum temperature at which enough vapors are given off to support continuous burning.

Exit access

The portion of the means of egress that leads to an exit.

Convection

The transfer of thermal energy by the circulation or movement of a liquid or gas

Fires are classified according to:

Their properties: the type of fuel feeding the fire

Class B fires

Usually involve flammable liquids and gases and typically start in kitchens and maintenance areas.

Class C fires

Usually involve live electrical equipment and typically occur in motors, switches, cords, circuits, and wiring.