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

8.10 Figure 8-1 Class K equipment.

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

8.12 Figure 8-2 Various types of fire extinguishers.

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 self-expelled 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 hand- pumped 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

8.15 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. (A)(B)(C)

8.16 Figure 8-6 Inner workings of a stored pressure water extinguisher.

8.17 Figure 8-10 Inner workings of a stored pressure dry chemical extinguisher.

8.18 Figure 8-14 Inner workings of a carbon dioxide extinguisher with a fixed nozzle.

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 8.19

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 8.20

Class B Test involves igniting a pan of flammable liquid, allowing a pre-burn 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 8.21

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 8.22

8.23 Figure 8-20 Class C test for electrical conductivity of agent.

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 8.24

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 8.25

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 8.26

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 8.27

8.28 Figure 8-21 (A) Unscrew and remove the top. (B) Add the manufacturer’s recommendation of water. (C) Add foam, if required. (A) (B) (C)

8.29 Figure 8-21 (cont’d.) (D) Replace the top. (E) Charge the extinguisher with the manufacturer’s recommendation of air. (D) (E)

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 8.30

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 8.31