Ch 6 - Fire Extinguishers

What's the maximum PSI above the extinguisher operating pressure that can be set?

25 psi above the extinguisher's operating pressure (107).

PASS

Pull Aim Squeeze Sweep (103)

Disadvantages in high application rate?

-Wasting chemicals -Having less discharge time (102)

Freeboard

1. The vertical distance from the normal water surface to the top of a confining wall. 2. The vertical distance from the sand surface to the underside of a trough in a sand filter (104/1087)

How often should fire extinguishers be inspected?

A minimum of 30-day intervals (106).

What does AGJ stand for?

Agency Having Jurisdiction (102)

Who needs an effective fire protection program that includes strategically-placed portable fire extinguishers?

All public buildings and workplaces (93).

Spill Fires

Are the easiest of all flammable liquid fires to extinguish with dry chemical. There is no leading edge (105).

Where should extinguishment begin on a fire?

Begin with the ground fire and then systematically continue extinguishment up to the source (105).

Who has a responsibility to protect their tenants and the public by maintaining a fire-safe environment?

Building owners and managers (93).

Pressured Water Extinguisher

Can be used on Class A fires only (95).

What extinguishing agent creates their own pressure and doesn't require the addition of a pressurizing gas to expel?

Carbon Dioxide (96).

Class A fire tests

Class 1A through 6A, extinguisher should be tested on appropriate wood-panel, wood-crib, and excelsior fires. For 10A rating, extinguisher should extinguish the 6A wood-panel fire plus appropriate 10A wood-crib fire test. 20A rating or higher, only the appropriate size wood-crib fire is required. The minimum allowable discharge time for extinguishers rated 2A and higher is 13 seconds. Extinguisher must be in full open position under continuous discharge. Must attack from distance of at least 6 feet, then may get closes but can't attack from the back of the crib (99-100).

Pressure Indicator (gauge)

Commonly known as the gauge, indicates whether the extinguisher has adequate pressure to operate properly (96).

Three-dimensional fire (gravity fed)

Involves flammable liquids in motion (105).

Dry Powders for Class D fires

Most Class D agents are applied generously to the burning material, often requiring up to 15 pounds of agent per pound of burning material. Extinguishing agent excludes oxygen and performs as a "heat sink" to absorb the thermal energy and cool the material (98).

What is the most important aspect of any fire extinguisher application technique?

Operator Safety (103).

What is NFPA 10?

Standard for Portable Fire Extinguishers (102). (*think 10lb extinguisher)

What is NFPA 48?

Storage and Handling of Magnesium (98).

Class K Fire Extinguisher

The can resembles a Class A pressurized water extinguisher, however, has a special nozzle and water solution designed for cooking oils and greases (95).

Nozzle (or hose/horn)

The device through which the agent is expelled (96).

Fuel in depth

The flammable liquid is confined to a certain area either by a vessel, berm or dike. Only the surface area is of concern, not the fuel beneath (104).

Handle

The means by which an extinguisher is carried. Normally the handle is located just below the level that you squeeze for discharge (96).

Water - as an extinguishing agent

Water is an excellent extinguishing agent suitable for Class A fires (ordinary combustibles) only. It cools the fuel below its kindling temperature. Never use on electrical equipment or for fires in cooking media. The water could flash to steam as a result of high temperatures and cause serious burns (96).

What type of fuels have flames that may not be visible?

Water-miscible (polar solvent) fuels (like alcohol) burn so cleanly that the flames may not be visible (104).

Carbon Dioxide Extinguisher

Commonly used against Class B and C fires (95).

Numerical Portion of Class B fires is based on?

Fire tests using square steel pans in specific size increments and a flammable, liquid test fuel similar to unleaded gas. Extinguisher classification is equivalent to 40% of the area of fire extinguisher twice by an expert operator (99).

Which side should a fire be fought?

Upwind side in order to stay out of the smoke, flames and radiant heat. Should be fought that allows a clear path of escape (103).

What is the safest and most successful way of extinguishing fires in the incipient or early stages?

Using extinguishers in teams (105).

Lever

What is squeezed or depressed to discharge the fire extinguisher's agent. On most extinguishers, the lever is located above the handle. In cartridge-operated extinguishers the discharge is accomplished by releasing the pressurizing gas into the cylinder (96).

What procedures should be followed when inspecting a fire extinguisher?

1) Pressure gauge reading or indicator in the operable range or position 2) Fullness determined by weighing 3) The discharge outlet is not broken 4) The seal is not broken 5) The operating instructions are clearly visible (106)

Dry Chemicals with Chain-breaking action

No physical properties of the fire are affected. Oxygen is not displaced, little cooling is accomplished, and the fuel is not removed. Either all is extinguished or non is extinguished (104)

Why are the five major classes of fires represented with pictures?

So that inexperienced users can quickly identify the correct fire extinguisher to use (94).

What are the three ways pressure can be generated for fire extinguishers?

Through the pressure in the main cylinder, having an outside cartridge, or through a manual pump (96).

Where, or how far, should the extinguisher stream start from the leading edge?

6" in front of the leading edge and the sweep or cut should begin at least 6" beyond the side of the fire and continue past 6" beyond the other side of the fire (104).

Sodium Bicarbonate (BC)

A regular dry chemical. Effective on Class B and C fires, also has effect on flaming stages of a Class A fire but no effect on embers or deep-seated Class A fire. When used on common cooking greases, it reacts with hot grease to form a thick foam through the saponification process, which extinguishes the fire through vapor securement, flame separation, and generation of steam. BC is alkaline in nature and will not cause corrosion during normal use (98).

Locking Mechanism

A simple, quick-release device that secures an extinguisher's lever to prevent accidental discharge (96).

Monoammonium Phosphate (ABC)

ABC dry chemical differs from potassium bicarbonate and sodium bicarbonate in its acidic nature. In addition to similar effectiveness on Class B and C fires compared to Sodium bicarbonate, monoammonium phosphate has unique effectiveness on Class A fires. When it contacts a burning surface of an ordinary combustible, a molten residue is formed. This residue coats the burning ember and excludes oxygen. Monammonium phosphate does not saponify when used on hot cooking grease and causes corrosion of not thoroughly removed from most hot surfaces (98).

Classes of fires

Class A: Ordinary Combustibles such as wood, paper, rubber, fabrics and many plastics. Class B: Flammable liquids and gases such as gasoline, oils, paint, lacquer, and tar. Class C: Fires involving live electrical equipment. (c for current) Class D: Combustible metals or metal alloys. Class K: Fires in cooking appliances that involve combustible cooking media such as vegetable or animal oils and fats (K for kitchen) (94).

Film-forming fluoroprotein foam

Forms like a film over a flammable liquid surface much like AFFFs (96).

How many dry chemical extinguisher operators should be present if there is an obstacle?

More than one (105).

What is NFPA 482?

Production, processing, handling and storage of Zirconium (98). (*2 looks like a Z)

Dry Chemical Extinguishers

Rated for Class A, B, and C fires. These extinguishers are commonly found in homes and commercial properties (95).

Stored Pressure Extinguishers

Store extinguishing agent inside the cylinder with the gas that provides the pressure needed to operate the unit (96)

Advantages in using higher application rates?

-Faster knockdown -Greater protection from radiant heat -Faster extinguishment on fuel in depth fires -Greater chances of extinguishment -Greater chances of extinguishing pressure -Obstacle -Three-dimensional fires (102)

Things to remember about a fire extinguisher

-Never discharge in someone's face -Never throw into a fire or leave unattended if the fire is not out. -Pressure buildup can cause an explosion (99).

Fire Extinguisher Basic procedures

1) Hold upright and pull safety pin 2) Stand back from fire and aim at the base of fire 3) Keep upright, squeeze handle and level together. Move closer as fire is extinguished. 4) When fire is out, back away and check for possible re-ignition. 5) Evacuate and ventilate the area immediately after use (103).

Alcohol type AFFF

A similar base to AFFF with the addition of copolymer. The copolymer reacts with water miscible fuels (polar solvents and hydrocarbon/polar-solvent mixtures containing 10% or more polar solvents) and reacts with the polar solvents to create a polymeric membrane (96). Mixes with the fuels and creates a

Aqueous film-forming foam (AFFF)

AFFF is made mostly of fluorochemical surfactants. The bubbles break, drain and lose their water, and form a film on the surface of the fuel that moves easily across the surface and prevents vapors from escaping (96). Creates a water film underneath the foam, on the top of the fuel, which cools the fuel below and stops the formation of flammable vapor.

Carbon Dioxide

Also known as CO2, is an odorless and colorless gas that does not conduct electricity. Stored in extinguishers as a liquid under pressure and when expelled, turns into a snow (dry ice) on contact with atmospheric moisture. Carbon Dioxide displaces oxygen and care should be taken in confined spaces. Avoid skin contact, can cause cold burns (99).

What type of fires should water extinguishers not be used for?

Combustible cooking media because water splatters grease and spreads the fire. Also, A stream of water on live electrical equipment can risk electric shock and establish a short circuit that could damage equipment (94).

Numerical Portion of Class A fires is based on?

Comparative fire tests using various sizes of wood-crib, wood-panel, and excelsior fires (99).

Class B fire tests

Conducted using a square steel pan at least 8 inches in depth. Ratings for up to and including 20B are conducted indoors in large-volume, draft-free room. For tests in excess of 20B, outdoor fire tests are conducted. May attack from only 1 side (101).

Potassium Bicarbonate (Purple K)

Dry chemical developed by the U.S. Naval Research Lab precluding the use of the term Purple K as a trade name. Potassium salts are far more effective on flammable liquid fires compared to sodium salts. Alkaline in nature, has similar abilities to saponfiy when used on hot cooking grease, and does not cause corrosion in most cases (98).

Fires are classified according to their _________?

Fuel (what is burning) (93). First question to ask "what type of fire is most likely to occur?"

Class D agents

Graphite (carbon) is a fine powder that must be applied with a dry scoop or shovel. The powder conducts heat away from the material, reducing its temperature below the point that combustion may be sustained. Sodium chloride-based powder forms a crust on the burning material, excluding oxygen in available in a 30-lb extinguisher. It also helps dissipate heat from the burning material. Pure copper powder was specifically developed for use on lithium fires (99).

What is NFPA 49?

Hazardous Chemicals Data (98).

What is NFPA 481?

Production, processing, handling and storage of titanium (98) (*1 looks like a t)

Wet chemical agents

Solutions of water mixed with potassium acetate, potassium carbonate, potassium citrate, or combinations thereof. Specifically designed for Class K fires but have superior effectiveness on Class A fires compared to plain water. Limited capabilities on Class B fires and can be used in extinguishers with special wand applicators on Class C fires, verifying that electricity cannot be conducted back to the operator (97).

Hydrostatic Testing

Subjecting the cylinder (the pressure vessel) to water pressure or pressure applied by some other non-compressible fluid, through the valve's opening, using a specially designed coupling. Dry chem required every 12 years. All others are 5 years (106-107).

What are the six basic parts of an extinguisher?

-Cylinder -Handle -Lever -Nozzle or horn -Locking mechanism -Pressure indicator (gauge) (96).

What are methods to ensure the foam is not submerged into the fuel, and instead is applied gently with minimal disturbance to the fuel surface?

-Deflecting the stream off the back edge -Bouncing the stream off the front edge -Deflecting it off an object in the center -Allowing the foam to gently fall down on the surface (known as "rain down" or "snowfall" technique) (103).

What factors may cause problems for fire extinguishment and the critical application rate?

-Wind direction and speed -Weather conditions -Length of pre-burn -Application technique -Fuel sources (102).

Critical Application Rate

The minimum rate at which the agent must be applied to the fire and is usually expressed as a ratio of quantity of agent (in pounds or gallons) per area unit (usually square foot) per time unit (either seconds or minutes) (101-102).

Autoignition Temperature

The minimum temperature to which a material must be raised before combustion will occur. Also called ignition temperature (97/1076).

Cylinder

The part of an extinguisher that contains the extinguishing agent. Stored-pressure extinguishers store their extinguishing agent in a cylinder with a gas that provides the pressure to operate the unit (96/1082).

Saponification

The process by which an alkaline solution reacts with fatty acids in a cooking medium to form a soapy foam on top of burning material. This secures the vapors and cools the cooking medium as the foam drains out and converts to steam (97/1102).

Foam Blanket

The result of a slow and dispersed foam application to reflect radiant heat away from the fuel source, insulates fuel by dispersing the heat away, and assists in smothering the fuel to create a fuel vapor barrier between the fuel and the fire (104/1087).

What is used to expel the extinguishing agents?

The use of pressure. Many extinguishers rely on a pressurizing gas to expel their agents. Some models store the pressurizing gas with the agent in the cylinder and others store the pressurizing gas externally in a separate cartridge. Some rely on a hand-operated pump (96).

Why do Wet chemical agents work on Class K fires?

They work through two methods. The soultion is alkaline in nature and reacts with the fatty acids in the cooking medium to form a soapy foam on top of the burning material. This secures the vapors and cools the cooking medium as the foam drains and converts to steam (known as Saponification). Additionally, the agent is discharged as a fine mist that does not submerge below the surface of the cooking medium (preventing a steam explosion), but rather it converts to steam on the surface pulling heat out of the material. Cooking-medium fires must be cooled below the Auto-ignition temperature to be successfully extinguished (97).

True or False: Never use ABC dry chemical, Halon 1211 or Halotron I fire extinguishers on fires involving oxidizers (pool chemicals).

True. A violent explosive reaction could occur with the mixture of the chemical. (101).

Halon Alternatives

Two popular Halon agents are in use since the ratification of the Montreal Protocol. FE-36 and Halontron I. Both extinguish fires primarily through cooling. Neither Halontron I nor Halon 1211 should be used in confined areas smaller than indicated on the extinguisher nameplate, food-preparation areas, or the presence of people with cardiac problems (99).

Underwriter Laboratories Inc

Underwriters Laboratories (UL) and other independent testing laboratories rate fire extinguishers according to the type of fires they can extinguish safely (94).

Halogenated agent

Used for firefighting since the early 1900s. Halogenated agents suppress fire by interrupting the chemical chain reaction in the combustion process, working in the fire chemically rather than physically. Two halogenated agents have been most common: Halon 1211 and Halon 1301. Both are ozone-depleting agents subject to control under the Montreal Protocol on Substances that Deplete the Ozone Layer and other federal requirements. Primary advantage is the lack of cleanup after the use of the agent. Use on electronics, data processing, jet engines, and high-tech equipment causes more damage on property than the fire itself (99).

Dry chemical extinguishing agents

Used since early 1900s. In early development, sodium bicarbonate was found to have great effectiveness on flammable liquid fires compared to other chemicals being used at the time. In the 1960s, major developments led to the introduction of potassium bicarbonate (Purple K), monoammonium phosphate (ABC), potassium chloride (Super K) and urea potassium (Monnex). Potassium chloride and urea potassium-based dry chemicals are not common in the U.S. market. Dry chemicals are nonpoisonous but the acidic-based (ABC) or alkaline-based (Regular or Purple K) chemicals could be an irritant if inhaled. Not recommended on delicate electrical equipment or aircraft due to damage beyond repair (98).

Water mist extinguisher

Uses deionized water that is discharged as a fine spray onto the burning material. Designed as an alternative to halon in areas where contamination must be kept to a minimum without the expense of halon substitutes. Using deionized water causes little damage to most electrical circuits and is the safest agent available for use on humans. Wand and wide spray with fine droplets gives a soft and controlled discharge pattern. This extinguisher passes the Underwriters Laboratories Inc. test for electrical conductivity, allowing it to be listed for Class C applications (97).