The one question that calls for serious thought before using or buying a fire extinguisher is this- What do the symbols on a fire extinguisher indicate?
If you are wondering why, imagine this- you have too many gadgets attached to a plug point which leads to a few sparks flying about. These end up attacking the box of tissue paper, and before you know it, you are confronted by the acrid smell of burning paper and plastic and have flames and sparks to go with it.
Your brain screams, “Fire- Do something”. But you have nothing to worry about since the fire extinguisher is within easy reach. You put it to use, expecting to bring the situation under control.
And then something terrible happens! The minute the fire retardant hits the now-charred electrical point, the sparks get out of control, spreading quickly to all the other points in the room. But how? The fire extinguisher was supposed to help, not make matters worse!
Does this mean fire extinguishers don’t work? Of course, they do. However, that’s only if you use the right kind of product for the fire you are dealing with. But, how do you know what fire extinguisher to own and use? Continue reading to find out…
So, what kind of symbols do fire extinguishers have?
Image from https://fireprevention.utexas.edu
1. Alphabets: A, B, C, D, and K are the letters you will find in the alphanumeric code used to describe the type and scope of a fire extinguisher. These letters are placed in geometric symbols, and the combinations used are standard, so there is no room for ambiguity. For instance:
· The letter “A” is always placed inside a triangle (black or green).
· The letter “B” will always be found inside a square (Black or red).
· The letter “C” will be seen inside a circle (black, metallic, or blue).
· The letter “D” is drawn inside a 5-pointed star (black or yellow).
· The letter “K” is depicted on its own or inside a hexagon (black even when all others are in color).
Even if you do not find these letters in the form of symbols, they will be used in the classification of the fire extinguisher. More on this coming up.
2. Pictographs: Some manufacturers use pictographs instead of alphabets simply to ensure that even those who don’t know the first thing about fire safety standards understand what is being conveyed. Often product makers like to play it safe hence they use both alphabetical symbols and pictographs, so this is what you are likely to see:
· For the letter “A”: The pictograph will always show a trashcan and some wood logs on fire.
· For the letter “B”: A barrel/can of fuel with flames on the side.
· For the letter “C”: Electrical plug and socket with flames around them.
· For the letter “D”: A bar of metal with flames emanating from it.
· For the letter “K”: A frying pan on fire
The pictographs and the alphabetical symbols depict the type of fire extinguisher; in other words, the type of fire that the product can be used to extinguish.
3. Numbers: These are placed before the alphabets in the classification, and they indicate the scope of use. Simply put, the number will tell you how big a fire the product can effectively handle.
Symbols that describe the type of fire that the extinguisher can control
The alphabets listed above stand for the class of fire that the extinguisher is meant to handle. Take a look at what these fire classifications are all about.
· Class A: This is a fire that involves ordinary combustible items such as paper, wood, rubber, fabric, cotton, cardboard, and some types of plastic. In a nutshell, these fires leave behind the residue of ash, hence the use of the letter “A” in its classification.
If you just see the alphabet “A” on the extinguisher, it means that the product can exclusively be used only on Class A fires and no other type.
· Class B: This type of fire results from combustible and flammable liquids and gases, such as gasoline, oil, kerosene, lacquers, oil-based paints, solvents, propane, etc. These flammable liquids are often stored in barrels, hence the use of the alphabet “B” in their symbolic depiction.
· Class C: These fires involve energized/live electrical equipment/points. For instance, the fire could result from faulty circuit breakers and fuse boxes, electric short circuits in machinery and gadgets and electrical wiring/cord, etc.
· Class D: You are unlikely to witness such a fire in a home setup because Class D fires involve flammable metals. So, they are likely to occur in laboratories where metals such as titanium, magnesium, potassium, and sodium are used.
· Class K: This type of fire is most commonly encountered in homes because it involves cooking media such as vegetable oil and animal fats.
So, a fire extinguisher that has just the letter “A” on it can only be used on Class A fires and not on any other class of fire. If the product is marked “B: C”, it means the extinguisher can be used against Class B and C fires but not against Class A.
The numbers that quantify the use of a fire extinguisher!
All fire extinguishers are labeled with a letter and a number. What does the number indicate? Although you won’t see numbers with pictographs, you will see a few listed alongside the alphabets in the classification of the product.
However, the numbers are only used before the letter “A” and the letter “B” while the other alphabets are left un-numbered. The answer to “why” is coming up in a bit.
The numbers that come before A: The rating in the case of A starts at 1A and goes to 2, 3, 4, 6, 10, 20, 30, and up to 40A. Each rating unit stands for the firefighting power of 1.25 gallons of water. So, a rating of 2A means that the extinguisher has the equivalent of 2.5 gallons of water, while a rating of 40A is equivalent to 50 gallons of water (equivalent to but not the actual quantity of water).
The numbers that come before B: In the case of Class B fires, the rating of the extinguishers start at 1 and goes to 2, 5, 10, 20, 30, 40, right up to 640. These numbers indicate the spread of fire in square feet that the product can put out. So, a rating of 1b means the extinguisher has the power to stop 1 square foot of Class B fire while 2B can put out flames spread across 2 square feet and so on.
The lack of ratings for Class C, D, and K extinguishers!
Class C has no rating because it simply stands for the fact that the fire extinguishing agent used does not conduct electricity. Hence, no rating is required.
Class D has no rating system because the flammability of combustible metals and the type and amount of extinguishing agent required to handle the fires caused by them vary significantly. Hence, a simple rating system would not work in case of such fire hazards.
In fact, the NFPA (National Fire Protection Association) has a separate standard for such fires. So, typically the label of the extinguisher will list the combustible metals that the product can be used on.
Class K: As is the case with Class D fires, the hazards of Class K also vary significantly in terms of both their flammability and the type and amount of fire retardant required. So, instead of a rating system, manufacturers provide extinguisher-size recommendations based on the specific hazards in the kitchen setup.
The different types of fire extinguishers
You already know that fire extinguishers differ based on the class of fire that they are effective against. So, the different types of extinguishers available in the market are simply combinations of firefighting power against different classes of fire. These are commonly available:
Type A: These products use water jet or mist/fog to extinguish Class A fires. Because water conducts electricity and can lead to the spread of flammable fluids, you cannot use Type A extinguishers on Class B, C, D, or K fires.
Type A and B: These work on both A and B fires because they typically contain a mix of water and foaming chemicals. The water in the mixture is effective against Class A fire, while the foam effectively covers the surface of the combustible fluid depriving the flames of fuel. However, these products don’t work against Class K fires, which involve free-flowing flames.
Type A, B, and C: The most versatile of the lot, these fire extinguishers are powder based and hence can handle 3 classes of fire. The dry chemical used as the extinguishing agent prevents back drafting in Class B fires and deprives Class A hazards of oxygen. Also, the dry powder does not conduct electricity, so it can tame a Class C fire as well.
While these extinguishers are effective against methane gas fires, they don’t work against Class K fires that involve oil/grease and other cooking gases. Also, when used against electrical fires, they do little to cool the appliance/gadget. Hence there is a risk of re-ignition.
Type B and C: These are CO2-based extinguishers hence they work against Class B and C fires. Because CO2 is inert, it does not conduct electricity hence it is safe for use on Class C fires.
Type K: These are wet chemical-based extinguishers that combine the firefighting power of water, potassium bicarbonate and sodium bicarbonate. Together, these manage to prevent the free-flow of the flames and deprive them of fuel by securing the surface of the combustible media and cooling it.
And after all that, are you ready for a test?
So, now that you know everything there is to the different classes and ratings of fire extinguishers test yourself with these classifications to see if you understand the firefighting power of a particular product.
1. What does this mean-6A-80B: C?
This is a powder-based extinguisher that gives you the firefighting power of (6 X 1.25) 7.5 gallons of water against Class A fires; it can control a Class B fire spread over 80 square feet, and it can also be used on electrical fires.
2. What does this mean- 10B:C?
This is a CO2-based extinguisher that will work on 10 square feet of Class B fire and can also be used on electrical fires.
3. What does this mean- 3A-10B?
This is a foam-based extinguisher that offers the equivalent of 3.75 gallons of water and can be used to control a Class B fire spread of 10 square feet.
If you got most or all of those correct, you are ready to move on to the next section.
How do you use a fire extinguisher safely?
PASS- This is a standard pneumonic given on the label to explain how best to use an extinguisher. But, before you do that, here are a few very important things that you need to remember in case of a fire:
· Activate the fire alarm system if you live in a building or apartment complex, so the other occupants and the fire department get notified.
· Do not try to fight the fire if you don’t know what is burning.
· Only use an extinguisher (no matter what type it is) on small fires. Let the firefighters handle the raging flames.
· If the fire is spreading rapidly beyond its point of origin, it is too late to use an extinguisher, and evacuation is the only option left.
· Do not fight a fire if it is too large for the capacity of your fire extinguisher.
· Do not try to fight a fire that is producing a lot of smoke. You are likely to encounter this when the fire is caused by synthetic fabrics such as nylon and foam padding, etc.
· Above all, if you have a bad feeling about it, don’t stick around to fight your instincts and the fire. Instead, let the fire department handle it for you.
· When using a fire extinguisher, always keep your back towards an exit point so that you can move back and away from the flames.
· Stand 10 to 20 feet away from the flames to minimize the risk of burns
With those covered, you are ready to use PASS:
P: Pull the pin to unlock the lever that can be pressed to discharge the fire extinguishing agent
A: Aim the hose or nozzle at the base/starting point of the fire. This will effectively put the extinguishing agent on the substance/thing that is burning.
S: Squeeze the lever/handle gently to release the extinguishing agent.
S: Sweep across the burning area side to side, so you cover all the flames and also any re-ignitions.
Wrapping it all up for you!
Now that you have an answer for “what do symbols on a fire extinguisher indicate”, you should have no trouble finding the right product for various areas of your home/office and using it the right way.
But even after all that- here is the most important piece of advice that you should not forget- Fires are dangerous and unpredictable. So no matter how good or versatile your fire extinguisher is, before you use it, ensure that you are not endangering yourself and those around you in an attempt to put out the flames yourself.
Also, in case of a fire, if you feel that someone is in immediate danger, your priority should be to remove this person from harm’s way, but only if this can be done without putting yourself at risk. Finally, even after the flames have been doused, get the fire site inspected by the fire department, particularly in the case of Class C and K fires.