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CXS490 - Portable Fire Extinguishers

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Virtually all fires are small at first and might be easily extinguished if the proper type and amount of extinguishing agent were promptly applied. Portable fire extinguishers are designed for this purpose, but their successful use depends on the following conditions:

Portable Fire Extinguishers

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Portable Fire Extinguishers• The extinguisher must be properly located and in good working order.• The extinguisher must be of the proper type for the fire which occurs.• The fire must be discovered while still small enough for the extinguisher to be effective.• The fire must be discovered by a person ready, willing and able to use the extinguisher.

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Portable fire extinguisher requirements are found in Building and Fire Codes.

Fire extinguishers are the first line of defence against unfriendly fires and should be installed regardless of other fire control measures. However, the fire department should be notified as soon as a fire is discovered; notification should never be delayed in hope that the extinguisher will be sufficient.

Requirements

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Portable extinguishers are tested by agencies such as Underwriters' Laboratories of Canada and, if found acceptable, listed by them.

The NFPA 10 Standard also deals with these equipments.

Testing & Standard

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NFPA 10 classifies fires in the following classes:

Class A:Fires in ordinary combustible materials such as wood, cloth paper, rubber and many plastics.

Class B:Fires in flammable and combustible liquids, gases, and greases.

Classes

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ClassesClass C:Fires which involve energized electrical equipment where the electrical non-conductivity of the extinguishing media is of importance.

Class D:Fires in combustible metals such as magnesium, titanium, zirconium, sodium and potassium

Class K:Fires of cooking appliances that use combustible cooking media (vegetable or animal oils & fats) .

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Some extinguishers put out only one class of firewhen some are suitable for two or three,but none is suitable for all four.

Listed extinguishers are labelledso that users may quickly identifythe class of fire for which they can be used.

Classes

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Extinguishers are rated according totheir fire-extinguishing potential.

The letter representing the class of firefor which it is suitable is accompanied,(for classes A and B), by a numeral whichindicates the relative extinguishingpotential of the device.

Ratings

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For class A rating, extinguishers are tested on wood crib and excelsior test fires. The wood crib consists of layers of nominal2 by 2 inches or 2 by 4 inches spruce.

The length, size and number of wood members varies as a function of the rating. Ignition is accomplished by burning of n-heptane in a pan placed under the crib.

Class A Rating

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Class A RatingTypically, a 2A fire would be extinguished by a 2 gallon extinguisher or a 5 lbs multipurpose dry chemical extinguisher

For the excelsior test fire, the mass of excelsior varies with the rating (1A corresponds to 3 kg of excelsior, and 6A corresponds to 16kg)

Excelsior - Wood wool wood sliver material used for packaging

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The flammable liquid test fires consist ofsquare metallic pan filled with n-Heptane.The number prior to B in the ratingcorresponds to 40% of the area of the panin square feet.

Trained user.

Class B Rating

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To qualify for class C rating, an extinguishermust be capable of being used onenergized electrical wiring and equipmentwithout electrical hazard to the operator.

Class C Rating

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Class D Rating

Often Dry Powder

Class D extinguishers are tested on metal fires. The agent used depends on the metal for which the extinguisher was designed.

Check the extinguisher faceplate for the unit's effectiveness on specific metals.

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Class D RatingMET-L-X

A dry powder composed of a salt base plus a polymer for sealing, and other additives to render it free-flowing and cause heat caking or crusting.

This agent is effective on sodium, potassium, sodium-potassium alloy and magnesium fires. In addition it will control and sometimes extinguish fires in zirconium and titanium.

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Class D RatingLITH-X was developed for use on lithium fires.will also extinguish magnesium, sodium and potassium fires. It will contain and in some cases completely extinguish fires of zirconium, titanium and sodium-potassium alloy.

LITH-X is a compound of special graphite base with additives to render it free-flowing so that it can be used in extinguishing equipment. It does not cake or crust like MET-L-X but excludes air and conducts heat away from the burning mass to extinguish the fire.

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Class "K" liquid fire suppressant for use on cooking equipment fires.

Class K Rating

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Class "K" liquid fire suppressants are a specially formulated, aqueous solution of inorganic salts. The agent is usually pre-mixed, eliminating the need for dilution before system charging.

When used as an extinguishing agent they produce no toxic by-products.

Class K Rating

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Class "K" liquid fire suppressant are designed for use in restaurant fire suppression systems. This ‘‘liquid’’ agent will combat grease-related fires as found in restaurant appliances and ventilating equipment.

They should not be used for fires involving energized electrical hazards.

Class K Rating

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Self-Expelling Extinguisher:An extinguisher in which the agents havesufficient vapour pressure at normal operating temperatures to expel themselves.

Definitions

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DefinitionsStored - Pressure Extinguisher:An extinguisher in which both the extinguishingmaterial and expellant gas are kept in asingle container and which includes apressure indicator or gauge.

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DefinitionsCartridge Operated Extinguisher:An extinguisher in which the expellant gasis kept in a separate container (or cartridge).Agent container put under pressure only atthe time of operation.

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• Water-based Extinguishers

• Carbon dioxide Extinguishers

• Dry Chemical Extinguishers

• Halocarbon Extinguishers

Types of Portables

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Include water, to which chemicals such as anti-freeze, loaded stream (alkali-metal salt), wetting agent, and AFFF may be added to improve the extinguisher's performance.

Extinguishers may be of the stored-pressure type or pump tank type. The duration of discharge of a water-based extinguisher is between 45 s to 120s. All except AFFF foam are for use on class A fires only.

Water Based

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Extinguishers are of the self-expelling type.Are suitable for classes B and C. Their approximate duration of discharge is between 8 s and 30s.

Carbon Dioxide

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Extinguishers can be of the stored pressure orthe cartridge operated type. Depending on the extinguishing agent they are suitable forclasses B and C only or for classes B, C, and A (multi-purpose dry chemical). Their discharge duration is in the range 8s to 30s.

Dry Chemical

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Extinguishers are suitable for classesB and C fires. Some may have limited ability to extinguish Class A fires. Their duration ofdischarge is in the range 8s to 25 s.

Halocarbon

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Extinguisher Colour Codes

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For Portable Fire Extinguishers

Refer to the applicableBuilding Code, Fire Code & NFPA 10.

In Canada all portable fire extinguishers are required to be listed by ULc or ULC

Installation Requirements

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Portable Usage

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Refer to the applicable Fire Code & NFPA 10.

Maintenance is required, even if the portable fire extinguisher was not originally required by the applicable code.

Inspection, Testing & Maintenance

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Inspections

The Ontario Fire Code, article 6.2.7.2., requires that portable extinguishers be inspected monthly. This entails a physical examination to determine that the device will perform in accordance with its intended function.

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InspectionsInspection should include confirmation that:a) is in its designated placeb) is conspicuousc) is not obstructed in any wayd) has not been actuated and partially or fully emptiede) has not been tampered with in any wayf) has not sustained any obvious physical damage or been subjected to any adverse environmental conditions which could interfere with its operation (such as corrosive fumes)g) sight gauge and tamper indicators show conditions to be satisfactory

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Hydrostatic TestingThe purpose is to safeguard against unexpected in-service failures from:a) undetected internal corrosion caused by moisture in the extinguisherb) external corrosion caused by atmospheric humidity or corrosive vapoursc) damage caused by rough handlingd) repeated pressurization contributing to metal fatiguee) manufacturing flaws in the constructionf) improper assembly of valves or safety relief disc, and g) exposure of the extinguisher to abnormal heat, as after exposure to fire.

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Hydrostatic TestingThe hydrostatic test involves using water pressure internally on the extinguisher shell over a determined length of time and at a pressure not to exceed 2587.5 kPa (375 psi).Fail ---> disposal NOT repair

A metal tag will be affixed to the extinguisher upon completion of the test indicating the date of the test.

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Hydrostatic TestingExtinguisher Type

Test Interval

(years)

Stored Pressure Water, Loaded Stream and/or Antifreeze 5

Wetting Agent 5

AFFF (Aqueous Film Forming Foam) 5

FFFP (Film Forming Fluoroprotein foam) 5

Dry Chemical with Stainless Steel Shells 5

Carbon Dioxide 5

Dry Chemical, Stored Pressure, with Mild Steel Shells,

Brazed Brass Shells, or Aluminum Shells 12

Dry Chemical, Cartridge or Cylinder

operated, with Mild Steel Shells 12

Halogenated Agents 12

Dry Powder, Stored Pressure, Cartridge-or

cylinder-Operated, with Mild Steel Shells 12