Fire with Extinguishers
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Fire Extinguisher
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A portable fire fighting device designed to combat incipient fires.
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Extinguishing Agents Work By:
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1: Smothering (oxygen exclusion) 2: Cooling (reducing the burning material below its ignition temperature) 3: Chain Breaking (interrupting the chemical chain reaction) 4: Saponification (forming an oxygen-excluding soapy foam)
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Extinguishing Agent
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Any substance used for the purpose of controlling or extinguishing a fire.
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NFPA Standard for Automotive Fire Apparatus
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1901. Requires that pumping apparatus have two approved portable fire extinguishers with mounting brackets and must be suitable for use on Class B and Class C fires.
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Water: Primary and Secondary Extinguishing Characteristics
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Primary: Cooling. Secondary: Oxygen Depletion.
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Carbon Dioxide: Primary and Secondary Extinguishing Characteristics
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Primary: Oxygen Depletion. Secondary: Cooling.
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Foam: Primary and Secondary Extinguishing Characteristics
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Primary: Oxygen Depletion. Secondary: Vapor Suppression.
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Clean Agent: Primary and Secondary Extinguishing Characteristics
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Primary: Chain Inhibition. Secondary: Cooling.
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Dry Chemical: Primary and Secondary Extinguishing Characteristics
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Primary: Chain Inhibition. Secondary: Oxygen Depletion
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Wet Chemical: Primary and Secondary Extinguishing Characteristics
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Primary: Oxygen Depletion. Secondary: Vapor Suppression.
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Dry Powder: Primary and Secondary Extinguishing Characteristics
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Primary: Oxygen Depletion. Secondary: Heat Transfer Cooling.
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Dry Chemical
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Extinguishing system that uses dry chemical powder as the primary extinguishing agent; often used to protect areas containing volatile flammable liquids.
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Class A Fires
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Involve ordinary combustibles such as textiles, paper, plastics, rubber and wood. These can be easily extinguished with water, water-based agents such as foam, or dry chemicals.
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Class B Fires
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Involve flammable and combustible liquids, gasses, and greases such as alcohol, cooking oils, gasoline, lubricating oils, and liquefied petroleum gas. Pressurized flammable liquids and gases are special fire hazards that should not be extinguished until the fuel gas is shut off. These fires get larger as the fuel volume increases. These fires can be extinguished with CO2, dry chemical and foam agents.
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Class C Fires
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Created by electricity energizing Class A or Class B fires. Water and water-based agents cannot be used to extinguish these fires until they are de-energized. Disconnect power supply, then use the appropriate extinguisher based on what is burning.
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Class D Fires
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Involve combustible metals such as magnesium, lithium, potassium or sodium. Identified by bright white sparks and emissions from combustion process. Special Class D Dry Chemical agents are used, however, do not confuse these agents with standard dry chemicals that are used on Class B and C fires. They will not work.
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Class K Fires
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Involve combustible cooking oils such as vegetable or animal fat oils that burn at extremely high temperatures. Wet Chemicals are used in the extinguishing systems and portable extinguishers or these fires.
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Conductivity
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The ability of a substance to conduct an electrical current.
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Alloy
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Substance or mixture composed of two or more metals (or a metal and nonmetallic elements) fused together and dissolved into each other to enhance the properties or usefulness of the base metal.
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Dry Powder
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Extinguishing agent suitable for use on combustible metal fires.
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Wet Chemical System
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Extinguishing system that uses a wet-chemical solution as the primary extinguishing agent; usually installed in range hoods and associated ducting where grease may accumulate.
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Pump-Type Water Extinguishers
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Intended for use on small Class A fires only. Equipped with either a single or double acting pump.
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Stored-Pressure Water Extinguishers
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Also called Air-Pressurized Water (APW) extinguishers. Useful for all types of small Class A fires, particularly for extinguishing small hot spots during overhaul operations. Typically water is stored in a tank along with either compressed nitrogen or air.
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Water-Mist Stored-Pressure Extinguishers
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Similar in appearance to standard stored-pressure water extinguishers, water-mist extinguishers use deionized water as the agent and nozzles that produce a fine spray instead of a solid stream. Because it is the impurities in water that make it electrically conductive, the deionized water also makes these Class A extinguishers safe to use on energized electrical equipment fires (Class C). The fine spray also enhances the cooling characteristics of water.
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Wet Chemical Stored-Pressure Extinguishers
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Similar in appearance to standard stored-pressure water extinguishers as well. These Class K units are specifically designed to control and extinguish fires in deep fryers. They contain a special potassium-based, low-pH agent formulated to cool and suppress fires in unsaturated cooking oils.
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Aqueous Film Forming Foam (AFFF) Extinguishers
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Suitable for use on Class A and Class B fires. particularly useful in combating fires in or suppressing vapors from small liquid fuel spills. Different from stored-pressure extinguishers in two ways: Contains a specific amount of AFFF concentrate mixed with water, and has an air-aspirating nozzle that aerates the foam solution, producing a better-quality foam than a standard extinguisher nozzle. When the AFFF and water are mixed, the resulting finished foam floats on the surface of fuels that are lighter than water. The vapor seal created by the film of water extinguishes the flame and prevents re-ignition. Not suitable for fires in Class C or D fuels, 3-D fires such as in fuel flowing down from an elevated point and fuel under pressure that is spraying from a leaking object. Most effective on static pools of liquids.
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Water Mist
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In the fire service, water mist is associated with a fire extinguisher capable of atomizing water through a special applicator. Water-mist fire extinguishers use distilled water, while back-pump type water-mist extinguishers use ordinary water.
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Aqueous Film Forming Foam (AFFF)
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Synthetic foam concentrate that, when combined with water, can form a complete vapor barrier over fuel spills and fires and is a highly effective extinguishing and blanketing agent on hydrocarbon fuels. Also called light water.
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Air-Aspirating Foam Nozzle
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Foam nozzle especially designed to provide the aeration required to make the highest quality foam possible; most effective appliance for the generation of low-expansion foam.
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Clean Agent Extinguishers
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Designed specifically as a replacement for Halon 1211. Include hydrochlorofluorocarbon (HCCF), hydrofluorocarbon (HFC), perfluorocarbon (PFC) or fluoroidiocarbon (FIC). These agents effecively cool and smother fires in Class A and B fuels, non-conductive and can be used on energized electrical equipment. If these agents are pressurized with Argon gas, they are approved by the EPA.
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Carbon Dioxide Extinguishers
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Both handheld and wheeled. Most effective in extinguishing Class B and C fires. Because their discharge is in the form of a gas, they have a limited reach and the gas can be dispersed by wind. They do not require freeze protection. Stored under its own pressure, discharge is usually accompanied by dry ice crystals or 'snow'. The CO2 displaces the oxygen and smothers the fire. No cooling effect or vapor suppressing film. CAUTION: When CO2 is discharged, a static electrical charge builds up on the discharge horn. Touching the horn before the charge has dissipated can result in shock.
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Dry Chemical Extinguishers
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Used for Class A, B and C fires or Class B and C. Types are 1-regular B:C rated and 2-multipurpose and A:B:C rated. Typically use Sodium Bicarbonate, Potassium Bicarbonate, Urea-Potassium Bicarbonate, Potassium Chloride or Monoammonium Phosphate. do not use with foam.
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Dry Powder Extinguishers
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Used for Class D fires only.
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Corrosive Materials
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Gaseous, liquid, or solid materials that can burn, irritate, or destroy human skin tissue and can severely corrode steel. Also called Corrosives.
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Handheld Dry Chemical Extinguishers
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Two types: Cartridge and stored pressure. Stored pressure has constant pressure of about 200 psi. Cartridge operated has no pressure until a plunger is pressed to release pressure. If using the cartridge type, do not place any portion of your body above the extinguisher in case the cap was not properly tightened.
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Wheeled Dry Chemical Extinguishers
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Similar to handheld, but on larger scale. Same ideas apply.
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Class D Extinguishers and Agents
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Some come in extinguisher form, others must be shoveled onto the fire. There is no single agent to control D fires. Most must be applied in sufficient depth to create a smothering 'blanket' on the fire. Apply gently so as not to break the forming crust. DO NOT apply water to a Class D fire. A violent reaction will ensue.
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Smothering
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The act of excluding oxygen from a fuel.
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Extinguisher Rating System
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Class A and B are rated according to performance capability, usually a number. Class A are rated 1-A through 40-A. Based on volume of water. 1-A contains 1.25 gallons or 5L water. 2-A contains 2.5 gallons or 10L of water. Class B ranges from 1-B through 640-B. This is the square footage of flammable fuel that the extinguisher can put out. Class C ratings confirm that the agent does not conduct electricity, and then either the A or B rating. Class D are metal specific, application instructions are on label. Class K must be capable of saponifying vegetable oils, peanut oils, canola oils with a surface area of 2.25 square feet.
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Symbols for Extinguishers
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A: Green Triangle. Trash can and campfire. B: Red Square. Gas can over pool of fire. C: Blue Circle. Electrical Cord and outlet with flames. D: Yellow Star. Smoking gear shaft. K: Black Hexagon. Frying pan on fire.
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Escape Route
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Pathway to safety. It can lead to an already burned area, a previously constructed safety area, a meadow that will not burn, or a natural rocky area that is large enough to take refuge without being burned. When escape routes deviate from a defined physical path, they must be clearly marked (flagged).
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Extinguisher Inspection Prior to Use
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External Condition-no apparent damage. Hose/Nozzle-in place. Weight-feels as though it contains agent. Pressure Gauge (if available)-in operable range. Do you have the correct class of extinguisher for your fire?
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PASS Method of Application
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P-Pull the pin. A-Aim the nozzle. S-Squeeze the handles together. S-Sweep the nozzle back and forth.
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Extinguisher Inspections
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NFPA 10 and most fire codes state they must be inspected once per year. Important to look at its serviceability, accessibility and simplicity of operation. 1-In its proper location? 2-Inspect nozzle of obstructions. 3-Inspect shell for any damage. 4-Instructions legible? 5-Locking pin and tamper seal intact? 6-Full and pressurized? If deficient by 10% it should be replaced, OOS. 7-Check inspection tag for date of previous inspection, maintenance or recharging. 8-Examine condition of the hose and fittings.
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Obsolete Extinguishers
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Inverted extinguishers. Carbon Tetrachloride and Chlorobromomethane extinguishers. Halon extinguishers.
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Halogenated Agents
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Chemical compounds (halogenated hydrocarbons) that contain carbon plus one or more elements from the halogen series. Halon 1301 and Halon 1211 are most commonly used as extinguishing agents for Class B and Class C fries. Also called Halogenated Hydrocarbons.
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Halogenated Agent Systems
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Extinguishing system that uses a halogenated gas as the primary extinguishing agent; usually installed to protect highly sensitive electronic equipment.
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Halon 1211
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Bromochlorodifluoromethane. Has been replaced by FE-36, hexafluoropropane.
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Halon 1301
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Bromotrifluoromethane. Has been replaced by FE-241, Cholotetrafluoroethane and FM-200, Heptafluoropropane.
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Total Flooding System
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Fire-suppression system designed to protect hazards within enclosed structures. Foam is released into a compartment or area and fills it completely to extinguish the fire.
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Halon Warning
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When halon is used to extinguish a fire, it can decompose and liberate toxic components. Therefore, do not use these agents in unventilated, confined spaces. If firefighters must enter areas flooded with these agents, they must wear SCBA.
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What are the five classes of fire and what do they involve?
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1-Class A-Fuels such as wood, paper, plastic, rubber and cloth. 2-Class B-Hydrocarbon and alcohol bases liquids and gases that will support combustion. 3-Class C-All fires involving energized electrical equipment. 4-Class D-Combustible metals such as magnesium, lithium, titanium, zirconium and potassium. 5-Class K-Unsaturated cooking oils in well insulated cooking appliances located in commercial kitchens.
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What fires are AFFF extinguishers most effective on?
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Class A and Class B fires.
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How do CO2 extinguishers work?
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Replaces and eliminates oxygen from the fire and smothers the fire.
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What are the 3 most common combinations for for extinguishers with multiple markings?
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Class A/B/C, Class A/B and Class B/C.
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List three factors that affect the selection of the proper portable fire extinguisher?
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1-Classification of fuel burning 2-Rating of the extinguisher 3-Hazards to be protected 4-Size and intensity of the fire 5-Atmospheric conditions 6-Any life hazard or operations concerns 7-Ease of handling extinguisher 8-Availability of trained personnel
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What should be checked immediately before using a portable extinguisher?
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1-No apparent external damage. 2-Hose and nozzle or horn are in place. 3-It feels as though it has agent in it when lifted. 4-Pressure gauge is in the operable range.
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What is the PASS method?
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Pull the pin. Aim the nozzle. Squeeze the handles together. Sweep the nozzle back and forth.
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What procedures should be part of every fire extinguisher inspection?
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1-In its proper location? 2-Obstructions in nozzle or horn? 3-Shell without damage? 4-Instructions legible? 5-Pin and seal tampered with? 6-Full and pressurized? If less than 10% from previous inspection, OOS and replace. 7-Check tag for previous inspections, maintenance or recharging. 8- Condition of hose and fittings?
