Transcript Chapter 8

Chapter 8
Portable Fire Extinguishers
Introduction
• Portable fire extinguishers designed
to fight:
– Small fires
– Unusual fires
– Fires that cannot be reached quickly
with hoselines
• Fire extinguishers are a valuable tool
8.2
Introduction (cont’d.)
• Four basic PASS steps
–
–
–
–
P: Pull the pin
A: Aim the nozzle
S: Squeeze the handle
S: Sweep the base of the fire
• Fire extinguishers come in a variety
of types and sizes
8.3
Fire Classification and Risk
• Type of material burning defines
class of fire
• Different classes of fire used to
identify type of extinguishers and
agents used
• Four traditional classes of fire
– Additional class added in the past few
years
• Have a pre-incident plan for fuel
types and locations
8.4
Class A
• Involves ordinary combustibles
• Can be extinguished with:
–
–
–
–
Water
Water-based agents
Foam
Multipurpose dry chemicals
• Water usually the agent used
8.5
Class B
• Flammable and combustible
liquids, gases, and greases
• Special hazards: situations where
fire extinguishers have not been
tested
• Common extinguishing agents:
– Carbon dioxide
– Regular and multipurpose dry
chemical
– Foam
8.6
Class C
• Involves energized electrical equipment
• Water-based agents cannot be used
• Turn off electrical power and use
appropriate extinguisher
• Categorized with another class of
extinguisher: BC or ABC
• Agents include:
– Carbon dioxide
– Regular and multipurpose dry chemicals
8.7
Class D
• Involves combustible metals and alloys
• Can have erratic behavior
• Water and other agents can react violently
when applied to burning combustible
metals
– Appear to explode when water applied
• No universal Class D extinguisher for all
metals
• Class D agents called dry powders
– Not to be confused with dry chemicals
8.8
Class K
•
•
•
•
New classification as of 1998
Fires in combustible cooking fuels
Agents are usually wet chemicals
Agents usually used in fixed systems
8.9
Figure 8-1 Class K equipment.
8.10
Types of Fire Extinguishers
• Many types available
• Factors for selecting an
extinguisher:
– Type and amount of fuel
– Person using extinguisher
– Type of building construction and
occupancy
– Type of equipment protected
• Main objective is extinguishing the fire
8.11
Figure 8-2 Various types of fire extinguishers.
8.12
Types of Extinguishing Agents
• Water is the basic agent for class A
materials
• Loaded stream extinguisher
• Water-based foam extinguishers have
either:
– Aqueous Film-Forming Foam (AFFF)
– Film-Forming Fluoroprotein Foam (FFFP)
• Carbon dioxide: inert gas stored under
pressure as a liquid capable of being selfexpelled
• Dry chemical agents: particles propelled
by gaseous medium
8.13
Kinds of Extinguishers
• Many types are in use today:
– Small and handheld
– Large and require a wheeled cart
• Pump-type extinguishers are handpumped devices of two designs
• Stored pressure extinguishers
expel gas to propel agent
• Cartridge-operated extinguishers
have expelled gas stored in
cartridge on side of container
8.14
(A)
(B)
(C)
Figure 8-3 (A) Older versions of fire extinguishers are labeled
with colored geometrical shapes with letter designations. (B)
Newer fire extinguishers are labeled with a picture label system.
(C) Many fire extinguishers can be used to fight more than one
type of fire.
8.15
Rating Systems for
Portable Extinguishers
• Each class of fuel is subjected to a
separate type of extinguisher test
for its class
• Usually conducted by independent
testing agency
• Appropriate ratings and symbols
are noted on label of extinguisher
8.16
Class A
• Testing utilizes wood cribbing
• Extinguisher should extinguish
about 1 cubic foot of wood cribbing
• Ratings increase as amount of fire
suppressed increases
– Class 2-A extinguisher puts out twice
the fire of 1-A
8.17
Class B
• Test involves igniting a pan of
flammable liquid, allowing a preburn period, and attacking the fire
• Size of pan determines rating
– 4-square-foot pan yields rating of 4-B
• Ratings based on inexperienced
extinguisher operator
• Larger fires require more agent per
area than smaller ones
8.18
Class C
• Testing tests only the conductivity
of:
–
–
–
–
Agent
Nozzle
Hose
Nozzle combination
• No actual fire test
• No numbers are assigned with
Class C rating
8.19
Figure 8-20 Class C test for electrical conductivity of
agent.
8.20
Limitations of Portable
Extinguishers
• Exceeding capabilities can cause damage
and injury
• Designed for specific purposes
• First-aid method for fire extinguishment
• Usually best to pick the larger size
• Wrong class extinguisher may not do the
job
– May cause a reaction or electrical shock
8.21
Portable Extinguisher
Operation
• PASS outlines four simple steps for
extinguisher use:
–
–
–
–
P: Pull the pin
A: Aim the nozzle
S: Squeeze the handle
S: Sweep the base of the fire
8.22
Care and Maintenance of
Portable Extinguishers
• Simple inspections and careful
storage prevent most problems
• Vehicle operators should
periodically move unit from its
bracket to hand test weight and do
visual check
8.23
Care and Maintenance of
Portable Extinguishers (cont’d.)
• Recharging water extinguisher is a
simple process
– Performed at fire station by any
firefighter
• Unscrew and remove the top
• Add the manufacturers recommendation
of water
• Add foam, if required
• Replace the top
• Charge the extinguisher with the
manufacturers recommendation of air
8.24
(A)
(B)
(C)
Figure 8-21 (A) Unscrew and remove the top. (B) Add the
manufacturer’s recommendation of water. (C) Add foam, if
required.
8.25
(D)
(E)
Figure 8-21 (cont’d.) (D) Replace the top. (E) Charge the
extinguisher with the manufacturer’s recommendation of air.
8.26
Inspection Requirements
• Many popular fire extinguishers of
the past are now obsolete
• Inspection of fire extinguishers is
usually a visual inspection
• If something does not look right,
extinguisher should be removed and
replaced
• Extinguishers returned to service
should be examined prior to their
placement on apparatus
8.27
Lessons Learned
• Fire extinguishers can be used as:
– Initial response tools
– To fight fires in special situations
• Firefighters classify fires by their
fuels
– Ordinary combustibles
– Flammable liquids and gases
– Energized electrical equipment
• Four-step process for using an
extinguisher: PASS
8.28