Chapter 6: Portable Fire extinguishers Flashcards
According to NFPA 1001 it was qualified at the fire fighter one level must know the following about portable fire extinguishers:
o Fire classifications
o Risks associated with each class of fire
o Operating methods of portable fire extinguishers
o Limitations of portable fire extinguishers
The firefighter one must be able to:
o Select appropriate extinguisher size and type
o Safely carry portable fire extinguishers
o Approach fire with portable fire extinguishers
o Operate portable fire extinguishers
how are extinguishers classified
Classified according to type of fire that each is designed to extinguish
how many classes of fire extinguishers are there and what are they
There five class is a portable fire extinguishers to match the five classes of fire: class A,B,C,D, and K
Portable fire extinguishers are identified by
the class letter or combination of letters
The three most common combinations of extinguishers
are class ABC, class BC in class AB
Class a and B extinguishers are classified by
with both letter and numerical rating systems
o for example 4 –A 20 – B:C ,should extinguish a class a fire that is four times larger than a 1– A fire, extinguisher approximately 20 times as much class B fire as a 1 – B extinguisher and extinguish a deep layer of flammable liquid fire of 20 ft.²
The classification a numerical rating system is based on
tests conducted by underwriters laboratories and underwriters laboratories of Canada
One system uses geometric shapes of specific colours with the class letter shown within the shape, the second system uses pictographs
Portable fire extinguisher rating: class A
rating
1-A through 40-A
(A=1 ¼ gallons of water)
- Primarily based on the amount of water and the duration and range of the discharge used in extinguishing test fires
explanations
1-A (1 ¼ gallons (5L) of water)
2-A ( 2 ½ gallons (10L) of water)
3-A (3 ¾ gallons (15L) of water) etc
Portable fire extinguisher rating: class B
1-B through 640-B
Explanations:
Based on the approximate square foot (square meter) Area of a flammable liquid fire a non-expert can extinguish
Portable fire extinguisher rating: class C
ratings
No extinguishing capability tests
Explanations
Tests are to determine non-conductivity
Portable fire extinguisher rating: class D
ratings
No numerical ratings
Explanations
Tested for reactions, toxicity and metal burnout time
Portable fire extinguisher rating: class K
ratings
No numerical ratings
explanations
Test to ensure effectiveness against 2.25 ft.² of light cooking oil in a deep fat fryer
Class a fires:
involve ordinary combustibles such as
o Textiles, plastics, wood, paper, rubber
class A fires can be extinguished with
water based agents like class a foam
- Dry chemicals will also extinguish fires fuelled by class A materials
how to calculate the water capacity of a class
To calculate the water capacity of a class extinguisher multiply the number in front of the A by 1 ¼ gallons (5L) (look at chart above)
Class B fire
involve flammable and combustible liquids and gases
Agents used to extinguish class B fire include
carbon dioxide, dry chemicals and class B foam
Flammable and combustible liquids and gases include:
o Alcohol, lubricating oil’s, gasoline, liquified petroleum gas
o Classified with numerical readings ranging from 1–B through 640-B
o Based on the appropriate square foot area of a flammable liquid fire that are non-expert operator can extinguish using one full extinguisher
o The non-expert operator is expected to extinguish one square foot for each numerical rating or value of the extinguisher rating
Class C fires
involve energized electrical equipment
class c’s are extinguished by
-Class C extinguishing agents will not connect electricity which makes them suitable for electrical fires
-Water and water based agents conduct electrical current and cannot be used on classifiers until the electricity has been shut off
- Power supply has been turned off or disconnected firefighters can treat the fire as a class a or B fire
-Class C rating confirms
that the extinguishing agent will not conduct electricity
-Class D fire
are those involving combustible metals and alloys such as
o Titanium, magnesium, sodium, lithium, potassium
-Magnesium fires can be identified by
the bright white omissions during the combustion process
-Some common uses a magnesium are in:
oCameras, laptops, luggage, metal boxsprings for beds, wheels and transmission components for automobiles
-The use of water or water based agents on class D fires
will cause the fire to react violently, emit bits of molten metal, and could injure nearby firefighters
o Use only class D rated fire extinguishers to extinguish metal fires
class d fires can be extinguished by
-Class D dry powder extinguishers
-Do not confused dry powder extinguishers with dry chemical units used on class A, B, and C fires
Class K fires
involve combustible cooking oils such as vegetable or animal fats and oil that burn at extremely high temperatures
what is used to extinguish class k fires
-Wet chemicals systems and portable fire extinguishers are used to control and extinguish Class K fires
how do class K fire extinguishers work
saponification
Wet chemical agents containing an alkaline mixture, such as potassium acetate, potassium carbonate, or potassium citrate, supress the vapors and smother the fire
Saponification:
converts the fatty acids or fats in the following oils to a soapy film:
o Vegetable oils
o Canola oils
o Peanut oils
o Other oils with little or no fatty acids
-Portable fire extinguishers are also rated according to
the type of extinguishing agent and the mechanism used to expel the contents
Smothering
excluding oxygen from the burning process
Smothering extinguishing agents will not work on material that contain their own oxidizing agents
Cooling
reducing the burning material below its ignition temperature
Chemical flame inhibition
interrupting the chemical chain reaction in the burning process
extinguishing techniques
smothering
cooling
chemical flame inhibition
saponification
Water type extinguishers must be protected against freezing if exposed the temperature is lower than _________ protection options include adding antifreeze to the water or storing them in warm areas
40F or 4 Celsius
Extinguishing agent characteristics: water
Primary method
Cooling
secondary method
Oxygen depletion
Extinguishing agent characteristics: carbon dioxide
Primary method
oxygen depletion
secondary method
cooling
Extinguishing agent characteristics: foam
Primary method
oxygen depletion
secondary method
vapour suppressing
Extinguishing agent characteristics: clean agent
Primary method
chain inhabitation
secondary method
cooling
Extinguishing agent characteristics: dry chemical
Primary method
chain inhabitation
secondary method
oxygen depletion
Extinguishing agent characteristics: wet chemical
Primary method
oxygen depletion
secondary method
vapour suppression
Extinguishing agent characteristics: dry powder
Primary method
oxygen depletion
secondary method
heat transfer cooling
All portable fire extinguishers expel their contents using one of the following mechanism
-manual pump
-stored pressure
-pressure cartridge
Manual pump:
the operator physically applies pressure to a pump that increases pressure within the container which forces the agent out of a nozzle at the end of the hose
Stored pressure
compressed air or inert gas within the container forces the agent out a nozzle at the end of a hose or when the operator presses the handle
Pressure cartridge
a separate cartridge on the side of the container contains inert gas. When the operator punctures the cartridge seal, the expellant enters the container and forces the agent out a nozzle on the end of a hose
common portable fire extinguishers include:
o Pump type water extinguish
o Stored pressure extinguishers
o Aqueous film forming foam extinguishers
o CO2 extinguishers
o Dry powder extinguishers
o Stored pressure water extinguishers
o Wet chemical stored pressure extinguishers
o Clean agent extinguishers
o Dry chemical extinguishers
Pump type water extinguishers:
primarily for use on ground cover fires although they may also be used for small class A fires
Operator usually wear pump type water extinguishers on their backs and use a manual operated slide pump the nozzle produces a straight stream, fog, or water mist pattern
Stored pressure water extinguishers:
these tanks Store water along with compressed air or nitrogen
o also called air pressurized water extinguishers, or pressurized water extinguishers
o useful for all types of small class A fires
- They are also useful for extinguishing confined hotspots during overhaul operations
- A gauge located on the valve assembly displays extinguishers pressure level
Stored pressure water mist extinguishers:
use deionized water is the agent and nozzles that produce a find spray instead of a solid stream
o Because impurities in water make it conduct electricity, the deionized water also makes these class A extinguishers safe to use on energized electrical equipment class C
Stored pressure wet chemical extinguishers
intended for use on class K fires involving cooking fats, greases and vegetable and animal oils in commercial kitchens
o Contain a special potassium-based, low pH agent formulated to operate on the principle of saponification
Aqueous film forming foam:
extinguishers are intended for class B fires they are particularly useful in compating fires in or suppressing vapours from small liquid fuel spills
Aqueous film forming foam Differ from storage pressure water extinguishers in two ways:
o Contains a specified amount of AFFF concentrate mixed with water to produce a foam solution
o Has an air aspirating foam nozzle that aerates the foam solution producing better quality foam
The water/AFFF solution is expelled using _____ or ________ in the tank with the solution
The water/AFFF solution is expelled using compressed air or nitrogen stored in the tank with the solution
The film of finished foam of aqueous foam creates a vapour seal that extinguishers the flame and prevent reignition
To avoid disturbing the foam blanket when applying in the foam
do not apply the foam directly onto the fuel; instead, allow it to rain down gently onto the fuels surface or deflect the foam off a nearby object or surface
Aqueous film forming foam is most effective when? not suitable when?
- Most effective on static pools of flammable liquids
- Not suitable for fires in class C, class D, or class K fuels
- Not suitable for situations as fuel flowing down from an elevated point and fuel under pressure spraying from a leak
Clean agents in Hallatron extinguishers
effectively cool and smother fires in class a and B fuels and inhibit the sustained chemical reaction in class C fuels
The agents are non-conductive and can extinguish energized electrical equipment fires
Clean agent extinguishers have been developed to replace
halons also known as halogenated extinguishing agents
o Halogenated extinguishing agents have a damaging affect on the atmosphere is ozone layer
o Halatron is an alternative clean agent that does not harm the ozone layer
Carbon dioxide extinguishers Most effective in extinguishing
class B in class C fires they discharge a gas with limited reach
Carbon dioxide extinguishers
-Store carbon dioxide under its own pressure as liquified gas
benefit and disadvantage of CO2 extinguishers
advantage
Wind will disperse extinguishing agent
- Store carbon dioxide under its own pressure as liquified gas
disadvantage
- They do not require freeze protection
- Carbon dioxide does not suppress the surface vapours of fuel therefore fuels may reignite
how does CO2 distinguisher work
- Usually forms dry ice crystals or carbon dioxide “snow”
o This snow changes from solid to a gas without becoming a liquid - The CO2 gas displaces available oxygen and smothered of fire, it has little if any cooling effects on fires
Dry chemical agents:
are for use on class A – B – C fires
Dry chemical extinguishers are among the most common
Dry powder agents:
are used only on class D fires
two basic types of dry chemical extinguishers
o Regular B -C rated
o Multipurpose an ABC rated
The following are commonly used dry chemicals:
oSodium bicarbonate, potassium bicarbonate, Uria potassium bicarbonate, potassium chloride, monoammonium phosphate
how to use a dry chemical extinguisher on a class A fire
direct the agents at the fuel in order to cover it with chemical. Once the flames have been knocked down, operator should apply the agent intermittently as needed on any smouldering areas
why do Manufactures mixed dry chemical agents with additives
make the agents moisture resistant and prevent them from caking
There are two basic designs for handheld dry chemical extinguishers:
cartridge operated and stored pressure
Storage pressure type hand held extinguisher
the agent Storage tank maintains a constant pressure of about 200 psi
Cartridge operated extinguishers:
employer pressure cartridge connected to the agent tank, operators push a plunger to release the gas from the cartridge and pressurize the agent tank
Both cartridge operated and stored pressure dry chemical agents use either ______ or ______ as the pressurizing agents
nitrogen or carbon dioxide
Caution when pressurizing a cartridge type extinguisher
do not place your head or any other part of your body above the top of the extinguisher, if the cap was not properly screwed back on the And or a cloud of agent can be forcibly discharged
Dry chemical wheels units
are larger versions of handheld unit. They are rated for class A,B, and C fires based on the dry chemical in the unit
- Extinguishing agent is kept in one tank and the pressurizing gas is stored in a separate cylinder
with wheeled unit extinguishers The operator should
stretch out the hose completely
- Operator should introduce the pressurizing gas into the agent tank and allow it a few seconds to fully pressurize the tank before opening the nozzle
- Caution the top of the extinguisher should be pointed away from the operator and any other nearby personnel when pressurize in the unit
Fires involve in class _______ require special dry powder extinguishing agent and application techniques
Class D
o No single extinguishing agent will control or extinguish fires in all combustible metals
with dry powder extinguishers the operator should
- Operator should apply the agent gently to avoid breaking any crust that may form over the burning metal
- To extinguish a fire field with a small amount of burning metal on a combustible surface, first cover the fire with powder. Then spread a layer of powder 1 to 2 inches deep nearby and shovel the burning metal onto this layer adding more powder as needed
Selecting the proper fire extinguisher
Select extinguishers at minimize the risk to life and property into effect of an extinguishing a fire
to make a selection of fire extinguisher consider the following factors:
o Classification of the burning feud
o Hazards to be protected against
o Atmosphere conditions
o Ease of handling the extinguisher
o Rating of the extinguisher
o Size and intensity of the fire
o Availability of train personnel to operate the extinguisher
o Any life hazard operational concerns
Even though fires in electronics or computer equipment our class C fires you should
select clean agent or carbon dioxide extinguishers to fight fires and highly sensitive computer equipment
o Dry chemicals normally used for electrical fires will leave a residue that could potentially do more damage to the computers than the fire itself
When inspecting and extinguisher immediately before use check the following:
o External condition: no apperant damage
o Hoze/nozzle- in place
o Weight- feels as though it contains agent
o Pressure gauge
how to us a portable fire extinguisher
o Approach the fire from Upwind that is with the wind at your back
o Once in position to attack the fire use the pass application method:
P- pull the pin breaking the thin wire plastic seal
A- aim the nozzle at the base of the fire
S- squeeze the handle scatter to release a short burst to test extinguisher, then squeeze continuously to release the agent
S- sweep the nozzle back-and-forth to cover the burning material
PASS
o Approach the fire from Upwind that is with the wind at your back
o Once in position to attack the fire use the pass application method:
P- pull the pin breaking the thin wire plastic seal
A- aim the nozzle at the base of the fire
S- squeeze the handle scatter to release a short burst to test extinguisher, then squeeze continuously to release the agent
S- sweep the nozzle back-and-forth to cover the burning material
Considerations relating to suppressing incipient fires of all classes include: (READ ALL)
o Remember that a portable extinguisher is a first aid firefighting appliance and does not take the place of an appropriate sized hose line
o Be sure the extinguishing agent reaches the fire if it cannot the agent will be wasted
o ensure that there is a clear exit for immediate escape should you need
o Smaller extinguishers require a closer approach to the fire than larger units, radiant heat or smoke may prevent you from getting close enough for the agent to reach the fire
o Adverse wins can limit the reach of an agent
o Operating an extinguisher close to the fire can sometimes scatter lightweight solid fuels or penetrate the surface of liquid fuels
o Apply the agent from a point where it reaches but does not disturb the fuel surface releasing the handles will stop the flow of the agent
o After the fire diminishes you may move closer to achieve final fire extinguishment
o If extinguishment is not achieved after an entire extinguisher has been discharged onto the fire withdrawal and reassess the situation
o “If a liquid fuel is burning it may be necessary to either apply the appropriate type of foam through a hose line or simultaneously attack the fire with more than one portable fire extinguishers
o For fires involving and energized electrical component attempt to shut off electricity to the component before attempting to extinguish the fire
o If more than one extinguishers use simultaneously work in unison with the other firefighters and maintain a constant awareness of each other’s actions and positions
o lay empty fire extinguishers on their side after use
Pump tank water extinguisher:
agent
Fire class
Stream reach
Agent; water
Class; a only
Stream reach; 30 to 40 feet
Stored pressure water extinguisher
Agent
Fire class
Stream reach
Agent: water
Fire class: A only
Stream reach: 30-40 feet
Aqueous film forming foam
Agent
Fire class
Stream reach
Agent; water and AFFF
Fire class: A and B
Stream: 20-25ft
Halon 1211
Agent:
Fire class:
Stream reach:
Agent: halon
Fire class: B &C
Stream reach: 8-18ft
Halon 1301
Agent:
Fire class:
Stream reach:
Agent: halon
Fire class: B&C
Stream reach: 4-6ft
Carbin dioxide
Agent:
Fire class:
Stream reach:
Agent: carbon dioxide
Fire class: B&C
Stream reach: 3-8ft (hand carried) 8-10ft (wheeled)
Dry chemical
Agent:
Fire class:
Stream reach:
Agent: sodium bicarbonate, potassium, bicarbonate, ammonium phosphate, potassium chloride
Fire class: B&C
Stream reach: 5-20ft
Multipurose dry chemical
Agent:
Fire class:
Stream reach:
Agent: Monoammonium phosphate
Fire class: A, B &C
Stream reach: 5-20ft
Dry powder
Agent:
Fire class:
Stream reach:
Agent: varies depending on metal fuel
Fire class: D only
Stream reach: 4-6ft
Wet chemical
Agent:
Fire class:
Stream reach:
Agent: potassium acetate
Fire class: K only
Stream reach: 8-12ft
