Types of fire extinguishing agents

Water. Water fire extinguishers extinguish the fire by taking away the heat element of the fire triangle.

Advantages of water as an extinguishing agent:

1. Water is relatively inexpensive when compared to other extinguishing agents such as

dry chemical, CO2, halons and foam.

2. Water is readily available in adequate quantities under most circumstances. However, sources of supply should not be assumed to be free of failure or infinite in

quantity.

3. With proper planning and forethought, water can be easily, safely and effectively used as a fire extinguishing agent.

Disadvantages of water as an extinguishing agent:

1. Water by itself will not extinguish flammable liquid fires under most circumstances.

2. Water can spread flammable liquid fires.

3. Use of water may increase the amount of hazardous materials requiring disposal.

4. Water may react with some materials creating excessive heat and toxic vapors.

5. In addition to spreading flammable liquids, when water is applied to a high flash point,

high viscosity liquid (such as asphalt), “frothing’ or “slop-over” may result.

6. Because of surface tension, water by itself has difficulty penetrating some dense,

deep seated class A fires, causing excessive run off and decreasing fire fighting

effectiveness.

7. Water can conduct electricity and may pose a safety hazard to fire fighting personnel

if proper, listed nozzles or other devices and precautions are not used.

8. 2 ½ gallon portable fire extinguishers weigh considerably more than similarly rated

extinguishers using other agents, weight may therefore be a factor for the personnel

using these extinguishers.

9. If water is used in conjunction with foam application it can disturb or destroy the foam

blanket, allow flammable vapors to be released.

Application of water on class A fires:

1. Effective streams are important when fighting class A fires.

2. Fuel for class A fires will not float on the surface of water like flammable liquids but

care should be taken in order to avoid damaging equipment or spreading dust by using the wrong stream pattern.

3. Overhaul techniques must be used in order to confirm that the fire is extinguished.

4. Some class A fires (tires, bales, rolled craft paper, wood chip piles) can be difficult to

penetrate.

Foam. Firefighting foams have been grouped into two main types: Chemical Foams and Mechanical Foams. Chemical Foams are rarely found still in use and have been replaced for the most part by different types of Mechanical Foams. Chemical Foams relied on a chemical reaction between two materials to produce a foam layer that blankets the flammable liquid surface and secures the vapors. A familiar example of chemical foam would be the old foam fire extinguishers that were constructed the same as soda-acid fire extinguishers. The mixing of a solution of sodium bicarbonate and foam stabilizers with an inner chamber containing a solution of aluminum sulfate would cause a chemical reaction that would create pressure expelling the agent and expanding the solution into foam.

Mechanical Foams refer to foam solutions that require a mechanical injection of air to expand and form bubbles. Some examples of mechanical foams are: Protein Foam, Fluoroprotein Foam, Aqueous Film Forming Foam (AFFF), Film Forming Fluoroprotein Foam (FFFP), Alcohol Type AFFF, Alcohol Type FFFP, Mid Expansion Foam and High Expansion Foam. All of these foams are sold in concentration, proportioned by different means into a foam concentrate/water solution and delivered to the fire as an expanded or finished foam. Foam concentrates are identified by percentages, 6%, 3%, 3-6% 1%. This percentage refers to the required amount of foam that must be mixed (proportioned) with water to make foam solution.

Carbon Dioxide. Carbon Dioxide fire extinguishers extinguish fire by taking away the oxygen element of the fire triangle and also be removing the heat with a very cold discharge.

Carbon dioxide can be used on Class B & C fires. They are usually ineffective on Class A fires.

Dry Chemical. Dry Chemical agents have unique properties for fire extinguishing applications. On class B fires they demonstrate superior "flame knock-down" over other available agents. Pound for pound they are unequaled in effectiveness when used properly on class B fires. Monoammonium phosphate has similar capabilities on class B fires plus the ability to effectively suppress class A fires. Dry Chemical fire extinguishers extinguish the fire primarily by interrupting the chemical reaction of the fire triangle.

Today’s most widely used type of fire extinguisher is the multipurpose dry chemical that is effective on Class A, B, and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.

Ordinary dry chemical is for Class B & C fires only. It is important to use the correct extinguisher for the type of fuel! Using the incorrect agent can allow the fire to re-ignite after apparently being extinguished successfully.

Wet Chemical. Wet Chemical agents are solutions of water mixed with potassium acetate, potassium carbonate, potassium citrate or combinations thereof. They are specifically designed for Class “K” fires but they have demonstrated superior effectiveness (gallon for gallon) on Class “A” fires when compared with plain water. These agents are used in both hand portable extinguishers and pre-engineered fixed systems.

Wet Chemical is an agent that extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the oxygen and fuel elements.

Wet chemical of Class K extinguishers were developed for modern, high efficiency deep fat fryers in commercial cooking operations. Some may also be used on Class A fires in commercial kitchens.

Clean Agent. Halogenated or Clean Agent extinguishers include the halon agents as well as the newer and less ozone depleting halocarbon agents. They extinguish the fire by interrupting the chemical reaction of the fire triangle.

Clean agent extinguishers are primarily for Class B and C fires. Some larger clean agent extinguishers can be used on Class A, B, and C fires.

Dry Powder. Dry Powder extinguishers are similar to dry chemical except that they extinguish the fire by separating the fuel from the oxygen element or by removing the heat element of the fire triangle. However, dry powder extinguishers are for Class D or combustible metal fires, only. They are ineffective on all other classes of fires.

Combustible metal fires represent a special hazard that is not like class A, B and C fires. Extinguishing agents used on all other classes of fires have no success when used on class D fires. In fact some agents, such as water, will react violently with the burning metal.

Most class D agents are applied generously to the material burning, often requiring up to 15 lbs. of agent per pound of burning material. The extinguishing agent will usually exclude oxygen and perform as a "heat" sink to absorb the thermal energy, cooling the material down. Caution must always be used when applying special agents to combustible metal fires since these fires will react with any moisture to be found in the ground or surrounding materials.

Water Mist. The Water Mist extinguisher uses de-ionized water that is discharged as a fine spray onto the burning material. It is designed as an alternative to halon in areas where contamination must be kept to a minimum without the expense of halon substitutes. The nozzle uses a wide spray pattern with fine droplets to give a soft and controlled discharge pattern. This extinguisher is listed for Class “C” applications.

Water Mist extinguishers are a recent development that extinguishes the fire by taking away the heat element of the fire triangle. They are an alternative to the clean agent extinguishers where contamination is a concern.

Water mist extinguishers are primarily for Class A fires, although they are safe for use on Class C fires as well.

Cartridge Operated Dry Chemical. Cartridge Operated fire extinguishers extinguish the fire primarily by interrupting the chemical reaction of the fire triangle.

Like the stored pressure dry chemical extinguishers, the multipurpose dry chemical is effective on Class A, B, and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.

 

 

APPENDIX 1

 

APPENDIX 2

 

Модальный глагол+перфектный инфинитив	Значение	Пример
Can have done Could have done	Неверие в событие или действие	She can ' t have overslept. – Она не могла проспать.
May have done Might have done	Предположение, неуверенность в произошедшем	She might not have known about it. – Она, возможно, и не знала об этом.
Must have done	Уверенность, высокая степень вероятности	I mustn't have taken keys. – Скорее всего я не взял ключи.
Will have done	Решимость, уверенность сделать что-либо	I won't have done it by the time you get back. – Я (не закончу) не сделаю этого к твоему приходу.
Would have done	Желаемое действие, которого не произошло	I would have come but I was stuck in traffic. – Я бы приехал,но я застрял в пробке.
Should have done	Невыполненное обязательство	I should have stayed home. – Мне следовало бы остаться дома.

 

 

APPENDIX 3

Таблица неправильных глаголов

Инфинитив:	Прошедшее время:	Причастие прош. времени:	Перевод:
A
awake	awoke	awaked; awoke	будить; проснуться
B
be	was; were	been	быть; нести; родить
bear	bore	born; borne	родить
beat	beat	beaten	бить
become	became	become	стать; сделаться
begin	began	begun	начать
bend	bent	bent; bended	согнуть(ся)
bet	bet; betted	bet; betted	держать пари
bid	bad; bade; bid	bid; bidden	велеть; просить
bind	bound	bound	связать
bite	bit	bit; bitten	кусать
bleed	bled	bled	кровоточить
bless	blessed	blessed; blest	благословлять
blow	blew	blown; blowed	дуть
break	broke	broken	(с)ломать
bring	brought	brought	принести
build	built	built	строить
burn	burnt; burned	burnt; burned	жечь; гореть
buy	bought	bought	купить
C
can	could	- / been able	мочь; уметь
cast	cast	cast	кинуть; лить металл
catch	caught	caught	ловить; поймать
choose	chose	chosen	выбрать
come	came	come	прийти
cost	cost	cost	стоить
cut	cut	cut	резать
D
dare	durst; dared	dared	сметь
deal	dealt	dealt	иметь дело
dig	dug	dug	копать
dive	dived; dove	dived	нырять; погружаться
do	did	done	делать
draw	drew	drawn	тащить; рисовать
dream	dreamt; dreamed	dreamt; dreamed	грезить; мечтать
drink	drank	drunk	пить; выпить
drive	drove	driven	гнать; ехать
dwell	dwelt	dwelt	обитать; задерживаться
E
eat	ate	eaten	кушать; есть
F
fall	fell	fallen	падать
feed	fed	fed	кормить
feel	felt	felt	чувствовать
fight	fought	fought	сражаться
find	found	found	находить
fly	flew	flown	летать
forbid	forbad; forbade	forbidden	запретить
forecast	forecast; forecasted	forecast; forecasted	предсказывать
foresee	foresaw	foreseen	предвидеть
forget	forgot	forgotten	забыть
forgive	forgave	forgiven	простить
freeze	froze	frozen	замерзнуть; замораживать
G
get	got	got	получить
give	gave	given	дать
go	went	gone	идти; уходить
grow	grew	grown	расти
H
hang	hung; hanged	hung; hanged	висеть; повесить
have	had	had	иметь
hear	heard	heard	слушать
hide	hid	hidden	прятать(ся)
hit	hit	hit	ударить; попасть
hold	held	held	держать
hurt	hurt	hurt	причинить боль
I
inset	inset	inset	вставлять; вкладывать
K
keep	kept	kept	хранить
kneel	knelt; kneeled	knelt; kneeled	становиться на колени
knit	knit; knitted	knit; knitted	вязать
know	knew	known	знать
L
lay	laid	laid	класть; положить
lead	led	led	вести
lean	leant; leaned	leant; leaned	опереться; прислониться
learn	learnt; learned	learnt; learned	учить
leave	left	left	оставить
lend	lent	lent	одолжить
let	let	let	пустить; дать
lie	lay	lain	лежать
light	lit; lighted	lit; lighted	осветить
lose	lost	lost	терять
M
make	made	made	делать
may	might	might	мочь; иметь возможность
mean	meant	meant	подразумевать
meet	met	met	встретить
mistake	mistook	mistaken	неправильно понимать
misunderstand	misunderstood	misunderstood	неправильно понимать
O
overcome	overcame	overcome	компенсировать, преодолевать
P
pay	paid	paid	платить
prove	proved	proved; proven	доказывать; оказаться
put	put	put	класть
Q
quit	quit; quitted	quit; quitted	покидать; оставлять
R
read	read; red	read; red	читать
rid	rid; ridded	rid; ridded	избавлять
ride	rode	ridden	ездить верхом
ring	rang	rung	звонить
rise	rose	risen	подняться
run	ran	run	бежать; течь
S
saw	sawed	sawn; sawed	пилить
say	said	said	говорить; сказать
see	saw	seen	видеть
seek	sought	sought	искать
sell	sold	sold	продавать
send	sent	sent	послать
set	set	set	устанавливать
sew	sewed	sewed; sewn	шить
shake	shook	shaken	трясти
shave	shaved	shaved; shaven	брить(ся)
shine	shone; shined	shone; shined	светить; сиять
shoot	shot	shot	стрелять; давать побеги
show	showed	shown; showed	показывать
shut	shut	shut	закрывать
sing	sang	sung	петь
sink	sank	sunk	опускаться; погружаться; тонуть
sit	sat	sat	сидеть
sleep	slept	slept	спать
slide	slid	slid	скользить
smell	smelt; smelled	smelt; smelled	пахнуть; нюхать
sow	sowed	sowed; sown	(по)сеять
speak	spoke	spoken	говорить
speed	sped; speeded	sped; speeded	ускорять; спешить
spell	spelt; spelled	spell; spelled	писать или читать по буквам
spend	spent	spent	тратить, проводить
spill	spilt; spilled	spilt; spilled	пролить
spin	spun; span	spun	прясть
spoil	spoilt; spoiled	spoilt; spoiled	портить
spotlight	spotlit; spotlighted	spotlit; spotlighted	осветить
spread	spread	spread	распространиться
spring	sprang	sprung	вскочить; возникнуть
stand	stood	stood	стоять
steal	stole	stolen	украсть
stick	stuck	stuck	уколоть; приклеить
sting	stung	stung	ужалить
stink	stank; stunk	stunk	вонять
strike	struck	struck	ударить; бить; бастовать
sweep	swept	swept	мести; промчаться
swim	swam	swum	плыть
swing	swung	swung	качаться
T
take	took	taken	взять; брать
teach	taught	taught	учить
tear	tore	torn	рвать
tell	told	told	рассказывать; сказать
think	thought	thought	думать
throw	threw	thrown	бросить
U
understand	understood	understood	понимать
undertake	undertook	undertaken	предпринять
upset	upset	upset	опрокинуть(ся)
W
wake	woke; waked	woken; waked	просыпаться; будить
wear	wore	worn	носить(одежду)
wet	wet; wetted	wet; wetted	мочить; увлажнять
win	won	won	выиграть
wind	wound	wound	заводить (механизм)
write	wrote	written	писать

 

APPENDIX 4