• How do I choose a Fire Extinguisher ?
• What are the typical Fire Extinguishers?
• Should You Fight The Fire Or Not? 
• How many types of fire extinguishers are there? 
• How are fire extinguishers labeled? 
• What are the single class ratings? 
• What are the multi-class ratings? 
• What are the different types of Fire Extinguishers? 
• How should Fire Extinguishers be used?
  

• Class A fires are ordinary solid materials like burning paper, wood , cardboard, clothes, plastics etc. Symbol A in a green triangle.
• Class B fires involve flammable or combustible liquids and gases such as gasoline, kerosene, LPG and common organic solvents like toluene, xylene. Symbol B in a red square.
• Class C fires involve energized electrical equipment, such as appliances, switches, panel boxes, power tools, hot plates and stirrers. Water is a particularly dangerous extinguishing medium for class C fires because of the risk of electrical shock. Symbol C in a blue circle.
• Class D fires involve combustible metals, such as magnesium, titanium, potassium and sodium as well as organometallic reagents such as alkyllithiums, Grignards and diethylzinc. These materials burn at high temperatures and will react violently with water or other chemicals. Handle with care!!

Some fires may be a combination of these! Your fire extinguishers should have ABC ratings on them. These ratings will often have numbers on them that look something like "3-A:40-B:C". Higher numbers mean more firefighting power. In this example, the extinguisher has a good firefighting capacity for Class A, B and C fires.

• Water extinguishers are suitable for class A (paper etc.) fires, but not for class B, C and D such as burning liquids, electrical fires or reactive metal fires. In these cases, the flames will be spread or the hazard made greater!
• Dry chemical extinguishers are useful for class ABC fires and are your best all around choice. They have an advantage over CO2 extinguishers in that they leave a blanket of non-flammable material on the extinguished material which reduces the likelihood of reignition. They also make a terrible mess -- but if the choice is a fire or a mess, take the mess! Note that there are two kinds of dry chemical extinguishers!
• Type BC fire extinguishers contain sodium or potassium bicarbonate.
• Type ABC fire extinguishers contain ammonium phosphate.
• CO2 extinguishers are for class B and C fires. They don't work very well on class A fires because the material usually reignites. CO2 extinguishers have an advantage over dry chemical in that they leave behind no harmful residue -- a good choice for an electrical fire on a computer or other delicate instrument. Note that CO2 is a bad choice for a flammable metal fires such as Grignard reagents, alkyllithiums and sodium metal because CO2 reacts with these materials. CO2 extinguishers are not approved for class D fires!

• Metal/Sand Extinguishers are for flammable metals (class D fires) and work by simply smothering the fire. You should have an approved class D unit if you are working with flammable metals.

When you are dealing with a fire, even a small one, you are in danger. Don't try to be a hero.
Fire doubles in size every minute it burns. That means that what is a small, contained fire one moment could easily engulf an entire room in a matter of seconds! Smoke and gases can be even more deadly than flames. In less than two minutes you can pass out or even die from poisonous gases and smoke.
It is much better to not even attempt to fight a fire unless you are certain that all occupants are moving to a safe area, that the fire department has been called and that you have at least one unobstructed exit behind you. Never fight a fire between you and the exit. If you are unsure of the danger or if there is any chance of the fire spreading to you, leave immediately! Close all doors behind you as you leave. Wait outside so that you can tell firefighters where the fire is located.
If the flames are as tall as you, if the room is getting smoky, if the heat from the fire is so hot that you can't get within five feet of it, or if you feel uneasy, you should not try to fight the fire, but should leave the building immediately.

There are basically four different types or classes of fire extinguishers, each of which extinguishes specific types of fire.

Newer fire extinguishers use a picture/labeling system to designate which types of fires they are to be used on. Older fire extinguishers are labeled with colored geometrical shapes with letter designations. Both of these types of labels are shown below with the description of the different classes of extinguishers.

Additionally, Class A and Class B fire extinguishers have a numerical rating which is based on tests conducted by Underwriter's Laboratories that are designed to determine the extinguishing potential for each size and type of extinguisher.

Q: What are the single class ratings?

Class A Extinguishers will put out fires in ordinary  combustibles, such as wood and paper. The numerical rating for this class of fire extinguisher refers to the amount of water the fire extinguisher holds and the amount of fire it will extinguish

	Class B Extinguishers should be used on fires involving  flammable liquids, such as grease, gasoline, oil, etc. The numerical rating for this class of fire extinguisher states the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish.
	Class C Extinguishers are suitable for use on electrically  energized fires. This class of fire extinguishers does not have a numerical rating. The presence of the letter "C" indicates that the extinguishing agent is non-conductive.

	Class D Extinguishers are designed for use on flammable metals and are often specific for the type of metal in question. There is no picture designator for Class D extinguishers. These extinguishers generally have no rating nor are they given a multi-purpose rating for use on other types of fires.

 

Q: What are the multi-class ratings?

	Many extinguishers available today can be used on different types of fires and will be labeled with more than one designator, e.g. A-B, B-C, or A-B-C. Make sure that if you have a multi-purpose extinguisher it is properly labeled.
	This is the old style of labeling indicating suitability for use on Class A, B, and C fires.
	This is the new style of labeling that shows this extinguisher may be used on Ordinary Combustibles, Flammable Liquids, or Electrical Equipment fires. This is the new labeling style with a diagonal red line drawn through the picture to indicate what type of fire this extinguisher is NOT suitable for. In this example, the fire extinguisher could be used on Ordinary Combustibles and Flammable Liquids fires, but not for Electrical Equipment fires

Q: What are the different types of Fire Extinguishers?

Dry Chemical  extinguishers are usually rated for multiple purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant.

	Halon extinguishers  contain a gas that interrupts the chemical reaction that takes place when fuels burn. These types of extinguishers are often used to protect valuable electrical equipment since them leave no residue to clean up. Halon extinguishers have a limited range, usually 4 to 6 feet. The initial application of Halon should be made at the base of the fire, even after the flames have been extinguished.
	Water  These extinguishers contain water and compressed gas and should only be used on Class A (ordinary combustibles) fires.

Carbon Dioxide (CO2) extinguishers  are most effective on Class B and C (liquids and electrical) fires. Since the gas disperses quickly, these extinguishers are only effective from 3 to 8 feet. The carbon dioxide is stored as a compressed liquid in the extinguisher; as it expands, it cools the surrounding air. The cooling will often cause ice to form around the "horn" where the gas is expelled from the extinguisher. Since the fire could re-ignite, continue to apply the agent even after the fire appears to be out.

Q: How should Fire Extinguishers be used?

Even though extinguishers come in a number of shapes and sizes, they all operate in a similar manner.  Here's an easy acronym for fire extinguisher use:

P  A  S   S  --  Pull, Aim, Squeeze, and Sweep 

 

	Pull the pin at the top of the extinguisher that keeps the  handle from being accidentally pressed.
	Aim the nozzle toward the base of the fire.
	Stand approximately 8 feet away from the fire and squeeze the handle to discharge the extinguisher. If you release the handle, the discharge will stop.
	Sweep the nozzle back and forth at the base of the fire. After the fire appears to be out, watch it carefully since it may  re-ignite!

Congratulations -- you did it!!!

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