Chapter 7 - Fire Extinguishers
`What areas of a fire extinguisher should you check as part of a quick visual inspection prior to using it
- External Condition: Free of damage - Hose / Nozzle: In place - Weight: Feels as though it contains agent - Pressure Gauge: In range (if applicable/available)
`What does NFPA require Firefighter 1 Level personnel to know about fire extinguishers
- Fire Classifications (A,B,C,D,K) - Risks within each Fire Classification - Operating Methods of Portable Fire Extinguishers - Limitations of Portable Fire Extinguishers
`Discuss the different types of expelling mechanisms of fire extinguishers
- Manual Pumps - Stored Pressure - Pressure Cartridge: Utilizes a separate cartridge on the side of the container.
`When you select a fire extinguisher, make sure it can do what
- Minimize the risk to life and property - Can effectively extinguish the fire
`Many areas of the fire extinguisher should be check during the beginning of the work period, or at least twice a week to include;
- Proper location of storage and accessibility - Check shell for any physical damage - Check to see if instructions on nameplate are visible - Check locking pin and safety seal - Check pressure by weighing Or inspecting agent level - Check inspection tag for last inspection date, maintenance, or recharging
`What do Firefighter 1 level personnel need to be able to do with portable fire extinguishers
- Select the appropriate extinguisher for size & type fire - Safely carry portable fire extinguishers - Approach fire with portable fire extinguishers - Operate portable fire extinguishers
`What are the three factors that determine the value of a fire extinguisher
- Serviceability - Accessibility - Simplicity of Operation
`What are the Fire Extinguisher different extinguishing methods
- Smothering: Excluding oxygen from burning process - Cooling: Reducing material below its burning temp. - Chain Breaking: Interrupting chemical chain reaction - Saponification: Forming oxygen-excluding soapy foam surface. Used to fight cooking oil fires.
`Discuss the different Classifications of Portable Fire Extinguishers
-CLASS A: Ordinary combustibles, to include; rubber, plastics. These fuels easily extinguished with water, class a foam, or dry chemical -CLASS B: Flammable/Combustible liquids & gases, to include. extinguished with C02, dry chem & Class B foam -CLASS C: Electrical. Class C extinguishers must be used until the electrical charge has been de-energized -CLASS D: Combustible metals and alloys, such as; lithium, magnesium, potassium, and "sodium". extinguish with dry powder (do not confuse this with dry chemical; which will react violently, similar to using water) -CLASS K: Combustible cooking oils that burn at very high temperatures. Use Class K extinguishers or "Wet Chemical Systems".
`How much of an agent weight loss is acceptable prior to having to remove the extinguisher from service
10%. Only trained personnel should refill portable fire extinguishers.
` Describe the weight and hose length on most Wheeled CO2 Extinguishers
50 to 100 lbs. 15' hose.
`How many square feet of a burning liquid should a non-expert be able to put out in respect to the numerical rating given.
A non-expert should be able to extinguish 1 square foot of a burning liquid pool for each numerical increase in the rating given. Example a 10-B rating should allow him to extinguish 10 Square feet. A 250-B Rating should allow him to extinguish 250 Square feet, etc...
`Saponification
A phenomenon that occurs when mixtures of alkaline based chemicals and certain cooking oils come into contact resulting in the formation of a soapy film.
`Discuss what is done to fire extinguishers as part of their annual maintenance/inspection required by NFPA 10
A thorough disassembly and inspection and Hydrostatic Testing as per NFPA 10 and the US Department of Transportation.
`Extinguishing Agent Characteristics (Primary and Secondary)
AGENT: PRIMARY / SECONDARY AFFECTS Water: Cooling / Oxygen Depletion Carbon Dioxide: Oxygen Depletion/Cooling Foam: Oxygen Depletion / Vapor Suppression Clean Agent: Chain Inhibition / Cooling Dry Chemical: Chain Inhibition / Oxygen Depletion Wet Chemical: O2 Depletion / Vapor Suppression Dry Powder: O2 Depletion / Heat Transfer-Cooling
`How often should fire extinguishers be cleaned
After each use and "periodically"
`Discuss the characteristics of Stored-Pressure Water Extinguishers
Also called Air-Pressurized Water Extinguishers (APW). Designed for small Class A fires and for hot spot extinguishing during overhaul operations. They are pressurized with either air or nitrogen. Sometimes Class A Foam is added to help extinguish deep seated fires by reducing the surface tension of the water and allowing quick penetration (Upholstered furninture, car seats, wildland fires, etc.)
`What do Class A ratings rate
Amount of extinguishing agent, range and duration of discharge. A simple way to think of it = a Class A 4-A should be able to extinguish a fire 4 times as large as a Class A 1
`Extinguishing Agent
Any substance used for the purpose of controlling or extinguishing a fire.
`There are many factors to consider when selecting a type of fire extinguisher to fight a fire, to include;
Atmospheric Conditions Availability of Trained Personnel Ease of Handling the Extinguisher Any Life Hazard or Operational Concerns
`Corrosive
Capable of causing corrosion by gradually eroding, rusting, or destroying a material.
`What is an acceptable way to carry a fire extinguisher
Carry it diagonally across the body with one hand on the handle and one on the bottom edge.
`Halogenated Extinguishing Agents (now banned for new installs)
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 fires. Also known as Halogenated- Hydrocarbons. They have been replaced by Clean Agents and are no longer being installed. Banned by EPA
`Discuss the Portable Fire Extinguisher Ratings
Class A use ratings 1-A though 40A in 5 water liter increments 1-A = 5 liters / 3-A = 15 liters, etc... Class B use ratings 1-B though 640B based on approximate square footage extinguishment area when applied by "non-experts" Class C only uses non-conductivity determination Class D only tested for metal burnout time, toxicity, and reactions. Instructions are printed on the nameplate of the extinguisher. No numerical rating given. Class K only ensures extinguishment of 2.25 square feet of cooking oil in a deep fat fryer.
`Multiple Fire Class Markings: which are some of the most common types of Multiple Class Fire Extinguisher combinations
Class A, B , C Class A, B Class B, C
`Discuss the Image Symbols for the different classes of fire extinguishers
Class A: Burning trashcan & Burning Wood Class B: Burning liquid by a fuel can Class C: Burning metal gear Class D: Burning electrical cord and outlet Class K: Burning frying pan All of the symbols are portrayed against a blue square
`Discuss the Letter Symbols for the different classes of fire extinguishers
Class A: Green Triangle with "A" Class B: Red Square with "B" Class C: Blue Circle with "C" Class D: Yellow Star with "D" Class K: Black Hexagon with "K" Note: The symbols kind-of look like the letter's shape, except for the Star/D symbol.
`What is a better kind of extinguisher to use in the above type rooms
Clean Agent or Carbon Dioxide type extinguishers
`When using Wheeled Dry Chemical Extinguishers, what are some important things to remember.
Completely unwrap the hose before use, to prevent Dry Chem from building up in an sharp bends and to make handling the hose easier and ensuring max reach of the hose. If the tank uses a separate pressurized canister, allow the canister to pressurize the tank for a few seconds before discharging the agent. Because of the size of the tank and nozzle, the operator should be prepared for a nozzle reaction upon discharge.
`Are inspection results recorded the same or differently on High Pressure and Low Pressure Hydrostatic Tests
Differently. Refer to NFPA 10 for specifics
`What type of fire extinguisher should not be used within highly sensitive computer rooms.
Do not use Dry Chemical Extinguishers in these types of room, The residue can cause more damage to the equipment than a fire. They can leave corrosive Particulate Residues
`What are the two types of markings to be printed on a portable fire extinguisher
Either Letter Symbols or Image Symbols
`Dry Powder
Extinguishing agent suitable for use on combustible metal fires.
`Wet Chemical System
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.
`Dry Chemical
Extinguishing system that uses dry chemical as the primary extinguishing agent; often used to protect areas containing volatile flammable liquids.
`Air-Aspirating Foam Nozzle
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.
~Dry Powder Extinguishers (Do not confuse with Dry Chem Extinguishers)
For Class D combustible metal fires. No extinguishing agent can properly extinguish all types of metal fires. Refer to the manufacturers technical sales literature.
` Dry Chemical Extinguishers
For use on Class A, B, & C Fires. Also for B-C fires. These are the most common types of Fire Extinguishers A moisture resistant agent is mixed in with the Dry Chem agent to prevent caking/hardening. Can be stored for long periods of time. When refilling, never mix with other types of agents; which could cause a chemical reaction over pressurization. Non-Toxic and safe to use. Some Dry Chem agents are compatible with foam; however, some other dry agents like Monoammonium-Phosphate and Sodium-Bicarbonate can cause foam blankets to deteriorate. Usually pressurized at 200 psi using carbon dioxide or nitrogen. For tanks utilizing separate pressurized cartridges, carbon dioxide is normally used unless the extinguisher will be subjected to sub freezing temperatures; in which case, the cartridges are pressurized with Nitrogen. Dry chem is capable of causing corrosion.
`From what direction should you approach a fire with a fire extinguisher
From the windward side (wind at your back)
`What type of PPE should be used with all fire extinguishers
Full Structural or Wildland PPE including "appropriate" respiratory protection.
`Discuss Clean Agent Extinguishers
Halotron Extinguishers pressurized with argon gas. They contain rapidly evaporting liquids that leave no residue in delicate areas, after they cool and smother fires. Can be used on; charged electrical equipment, Class B fires and Class A fires. These are newly approved Clean Agent Extinguishers; which replace older Halogenated-Hydrocarbon Extinguishers (which were generically referred to as Halon)
`Which one is preferred by NFPA 10
Image Symbols
`Where should you perform the refilling of Dry Chemical Extinguishers
In a controlled atmosphere, to prevent the agent from spreading through the area.
`Water-Mist
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/deionized water, while backpack-pump type water-mist extinguishers use ordinary water. The mist enhances cooling of the burning material and reduces scattering of materials
`What fire growth stages are portable fire extinguishers designed for
Incipient and "early" growth stages. Primarily, they are intended for occupant use.
` Discuss Aqueous Film Forming Foam (AFFF) Extinguishers
Intended for Class B fires by suppressing vapor from small liquid fuel spills. They have air aspirating foam nozzles. Expelled with compressed air or nitrogen stored within the tank with the contents. Spray in an upward arch so that it gently rains down on top of the fuel, or bank it off a nearby object. They are most effective on static pools of fuel. Note: AAAF is corrosive.
`How often should you shake dry chemical extinguisher in order to keep the agent loose in the container and prevent settling.
Monthly
`What agency and regulation governs portable fire extinguishers
NFPA 10 - Standard for Portable Fire Extinguishers
`What agency and regulation governs fire extinguishers
NFPA 10. Also follow your departmental SOP
`How often should fire extinguishers be inspected
NFPA and most Life Safety Codes require at least annual inspections to ensure availability and operation ready. Also follow your departmental SOPs
`In what way does our text book describe a portable fire extinguisher, in reference to what it is like as compared to a fire hose
Our book references the fire extinguisher as being a first -aid fire fighting appliance, which does not take the place of an appropriate-sized hoseline.
`What is a good acronym to use when utilizing a fire extinguisher to extinguish a fire
P - Pull the pin, breaking the thin wire or plastic seal A - Aim the nozzle at the base of the fire S - Squeeze the handles together S - Sweep the nozzle back and forth to cover material
Fire Extinguisher
Portable fire fighting device designed to combat incipient fires.
`How often should you inspect the fire extinguishers on a apparatus you are assigned to.
Preferably at the beginning of each work period, or at least weekly.
`Discuss the characteristics of Pump Type Water Extinguishers
Primarily intended for use on ground cover fires and small Class A fires. They normally use a straight stream, fog, or water mist pattern.
`How should fire extinguishers be stored after use at a fire scene
Store them laying on their sides, as an indication that they are empty.
`At what temperature do you need to start protecting water fire extinguishers from freezing, and what can help prevent freezing if exposed to lower temperatures
Temperatures lower than 40 degrees. Consider adding antifreeze or storing in warmer areas.
`Carbon Dioxide (CO2) Extinguishers
These are the most effective at extinguishing Class B and C fires. They have limited reach and can be dispersed by wind. Stored under its own pressure as a liquefied gas, discharged through a plastic or rubber horn. The horn can build up an electrical charge and produce a shock if it is touched before the gas dissipates. The CO2 emerges along with dry ice or CO2 Snow and quickly evaporates without turning into a liquid. It displaces the oxygen and smothers the fire. Even though it comes out at subzero temperature, it does little to cool the fire; rather, it creates a vapor suppressing film on the surface of the fuel. Reignition is always a danger.
`Discuss Wet Chemical Stored-Pressured Extinguishers
They look similar to stored pressure water extinguishers but are labeled with the letter K. They contain a special potassium-based, low pH agent formula to achieve Saponification.
`Discuss the hazards of using privately owned fire extinguishers
They may be obsolete or inoperative due to neglected maintenance or vandalism. You should only use fire extinguishers off your apparatus.
`Why should Dry Powder be applied gently to a metal fire
To avoid breaking any formed crust over the burning metal. It also helps to avoid scattering the burning metal. If a small metal fire is burning on a combustible floor, the metal fire should be extinguished first, then you should apply a 1 to 2" pile of powder nearby, and gently scoop and move the metal on top of the pile of powder. Add more powder as needed. Let metal completely cool before disposal
`There are many different types of extinguisher containers which discharge many types of agents. As a rule of thumb how far will hand carried extinguisher agents travel and for how long of a time
Water & Foam: 20 to 40' for approximately 45 seconds Most Chemicals: About 5-10' for approx. 10-30 seconds Dry Powder: Does not travel far 5' Wet Chemical: Can have a long discharge time 80 sec. Wheeled Chemical tanks can double distance and time.
`Deionized Water
Water from which ionic salts, minerals, and impurities have been removed by ion-exchange. It is free of impurities and therefor can not conduct electricity and can be used on electrical fires.
`Do test results need to appear on the fire extinguisher
Yes, affixed to the exterior shell of the extinguisher
`Are there any other requirements for Dry Chemical Agents
Yes, they are limited to 6 years of agent storage. The agent must be emptied from the container after 6 years and refilled with fresh Dry Chemical Agent.