Chapter 8 Portable Fire Extinguishers Introduction Portable fire

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-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 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 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

Figure 8 -6 Inner workings of a stored pressure water extinguisher. 8. 16

Figure 8 -10 Inner workings of a stored pressure dry chemical extinguisher. 8. 17

Figure 8 -14 Inner workings of a carbon dioxide extinguisher with a fixed nozzle. 8. 18

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

Figure 8 -20 Class C test for electrical conductivity of agent. 8. 23

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

(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. 28

(D) (E) Figure 8 -21 (cont’d. ) (D) Replace the top. (E) Charge the extinguisher with the manufacturer’s recommendation of air. 8. 29

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