Fire Extinguishers: Class A

Fire extinguishers
Introduction
This is The Fire Triangle. Actually, it's a tetrahedron, because there are four
elements that must be present for a fire to exist. There must be oxygen to sustain
combustion, heat to raise the material to its ignition temperature, fuel to support the
combustion and a chemical reaction between the other three elements.
Remove any one of the four elements to extinguish the fire.
The concept of Fire Protection is based upon keeping these four elements separate.
Types of Fires
Not all fires are the same. Per NFPA 10, burning may be classified into one or
more of the following fire classes and your fire protection specialist will select the
right fire extinguisher size and agent for the hazard.
Class A
Class A fires are fires in ordinary
combustibles such as wood, paper,
cloth, rubber, and many plastics.
Class B
Class B fires are fires in flammable
liquids such as gasoline, petroleum
greases, tars, oils, oil-based paints,
solvents, alcohols. Class B fires also
include flammable gases such as
propane and butane. Class B fires do
not include fires involving cooking oils
and grease.
Class C
Class C fires are fires involving
energized electrical equipment such as
computers, servers, motors,
transformers, and appliances. Remove
the power and the Class C fire becomes
one of the other classes of fire.
Class D
Class D fires are fires in combustible
metals such as magnesium, titanium,
zirconium, sodium, lithium, and
potassium.
Class K
Class K fires are fires in cooking oils
and greases such as animal and
vegetable fats.
Some types of fire extinguishing agents can be used on more than one class of fire.
Others have warnings where it would be dangerous for the operator to use on a
particular fire extinguishing agent.
Types of Fire Extinguishers
Water and Foam

Water and Foam fire extinguishers extinguish the fire by taking away the heat
element of the fire triangle. Foam agents also separate the oxygen element from the
other elements.
Water extinguishers are for Class A fires only - they should not be used on Class B
or C fires. The discharge stream could spread the flammable liquid in a Class B
fire or could create a shock hazard on a Class C fire.
Carbon Dioxide
Carbon Dioxide fire extinguishers extinguish fire by taking away the oxygen
element of the fire triangle and also be removing the heat with a very cold
discharge.
Carbon dioxide can be used on Class B & C fires. They are usually ineffective on
Class A fires.
Dry Chemical
Dry Chemical fire extinguishers extinguish the fire primarily by interrupting the
chemical reaction of the fire triangle.
Today's most widely used type of fire extinguisher is the multipurpose dry
chemical that is effective on Class A, B, and C fires. This agent also works by
creating a barrier between the oxygen element and the fuel element on Class A
fires.
Ordinary dry chemical is for Class B & C fires only. It is important to use the
correct extinguisher for the type of fuel! Using the incorrect agent can allow the
fire to re-ignite after apparently being extinguished succesfully.
Wet Chemical
Wet Chemical is a new agent that extinguishes the fire by removing the heat of the
fire triangle and prevents re-ignition by creating a barrier between the oxygen and
fuel elements.
Wet chemical of Class K extinguishers were developed for modern, high efficiency
deep fat fryers in commercial cooking operations. Some may also be used on Class
A fires in commercial kitchens.
Clean Agent
Halogenated or Clean Agent extinguishers include the halon agents as well as the
newer and less ozone depleting halocarbon agents. They extinguish the fire by
interrupting the chemical reaction and/or removing heat from the fire triangle.
Clean agent extinguishers are effective on Class A, B and C fires. Smaller sized
handheld extinguishers are not large enough to obtain a 1A rating and may carry
only a Class B and C rating.
Dry Powder
Dry Powder extinguishers are similar to dry chemical except that they extinguish
the fire by separating the fuel from the oxygen element or by removing the heat
element of the fire triangle.
However, dry powder extinguishers are for Class D or combustible metal fires,
only. They are ineffective on all other classes of fires.
Water Mist
Water Mist extinguishers are a recent development that extinguish the fire by
taking away the heat element of the fire triangle. They are an alternative to the
clean agent extinguishers where contamination is a concern.
Water mist extinguishers are primarily for Class A fires, although they are safe for
use on Class C fires as well.
Cartridge Operated Dry Chemical

Cartridge Operated Dry Chemical fire extinguishers extinguish the fire primarily
by interrupting the chemical reaction of the fire triangle.
Like the stored pressure dry chemical extinguishers, the multipurpose dry chemical
is effective on Class A, B, and C fires. This agent also works by creating a barrier
between the oxygen element and the fuel element on Class A fires.
Ordinary dry chemical is for Class B & C fires only. It is important to use the
correct extinguisher for the type of fuel! Using the incorrect agent can allow the
fire to re-ignite after apparently being extinguished successfully.
The Rules for Fighting Fires

Just remember the three A's
ACTIVATE the building alarm system or notify the fire department by calling 911.
Or, have someone else do this for you.
ASSIST any persons in immediate danger, or those incapable on their own, to exit
the building, without risk to yourself.
Only after these two are completed should you ATTEMPT to extinguish the fire.
Only fight a fire if:
 The fire is small and contained
 You are safe from toxic smoke
 You have a means of escape
 Your instincts tell you it's OK
Fire Extinguisher Use

Itis important to know the locations and the types of extinguishers in your
workplace prior to actually using one.
Fire extinguishers can be heavy, so it's a good idea to practice picking up and
holding an extinguisher to get an idea of the weight and feel.
Take time to read the operating instructions and warnings found on the fire
extinguisher label. Not all fire extinguishers look alike.
Practice releasing the discharge hose or horn and aiming it at the base of an
imagined fire. Do not pull the pin or squeeze the lever. This will break the
extinguisher seal and cause it to lose pressure.
When it is time to use the extinguisher on a fire, just remember PASS!
Pull the pin.
Aim the nozzle or hose at the base of the fire from the recommended safe distance.
Squeeze the operating lever to discharge the fire extinguishing agent.
Starting at the recommended distance, Sweep the nozzle or hose from side to side
until the fire is out. Move forward or around the fire area as the fire diminishes.
Watch the area in case of re-ignition.
Fire Extinguisher Inspection

Like any mechanical device, fire extinguishers must be maintained on a regular
basis to ensure their proper operation. You, the owner or occupant of the property
where the fire extinguishers are located, are responsible for arranging your fire
extinguishers' maintenance. Fire extinguishers must be inspected or given a "quick
check" every 30 days.
Fire Extinguisher Maintenance

In addition, fire extinguishers must be maintained annually in accordance with
local, state, and national codes and regulations. This is a thorough examination of
the fire extinguisher's mechanical parts, fire extinguishing agent, and the expellant
gas. Your fire equipment professional is the ideal person to perform the annual
maintenance because they have the appropriate servicing manuals, tools, recharge
materials, parts, lubricants, and the necessary training and experience.

Fire Extinguishers: Class A

Uploaded by

Copyright:

Available Formats

Fire Extinguishers: Class A

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Fire Extinguishers: Class A

Uploaded by

Copyright:

Available Formats

Fire extinguishers

Types of Fire Extinguishers

Water and Foam

Cartridge Operated Dry Chemical

The Rules for Fighting Fires

Fire Extinguisher Use

Fire Extinguisher Inspection

Fire Extinguisher Maintenance

You might also like