24 Jun Classes of fire and extinguishers.
Making the decision to embark on fire fighting training is a brave and rewarding one, where you will be joining a dutiful profession of saving lives. Because of the nature of the job, firefighters have to undergo extensive training to ensure that they are able to effectively and efficiently fight fires as well as respond to emergencies. Emcare is one of South Africa’s top training academies and offers numerous courses, including fire fighting training, where you will learn about the different classes of fires that you could encounter on the job, and how to handle these differing fires.
Classes of Fire
In fire fighting training you will learn that Class A fires are one of the most common classes, and includes fires involving solid combustibles and materials such as wood, paper, furniture and clothing, as well as plastics. These fires are so common because the powerful fuel for the fire is everyday objects that are generally found in most homes, offices and factories. Class A fires can range from small to mass destruction and they can be incredibly difficult for fire fighters to extinguish because there are so many objects that act as fuel and catch alight as the fire keeps burning.
For Class A fires, a water fire extinguisher needs to be used as water is the most effective at putting out Class A fires. Thankfully, when you begin your fire fighting training at Emcare you will receive meticulous guidance and direction on the different purposes of different extinguishers, and how to hold the hose correctly so that you are swiftly outing the fire. You will also learn about the different speeds at which these Class A materials can burn and how to approach a large-scale Class A fire.
A Class B fire involves flammable liquids and is difficult to maintain because so many daily products contain flammable liquids. These liquids that could be in Class B fires are gasoline, adhesives, petroleum greases, solvents, alcohols, tars, oils, and oil-based paint, but does not include kitchen grease fires or cooking oil fires, those are classed in Class K. Unfortunately, these fires are also quite common and when they do occur, it is often in a factory or workplace which contains these flammable liquids.
The combustive and explosive nature of these fires means that they can be incredibly dangerous for all those involved, and are actually the most deadly. Data taken from a 2011 study on flammable liquids found that although flammable liquid fires accounted for only 2% of occurring fires, they did account for a whopping 21% of fatalities, highlighting just how important it is to prevent these fires and be equipped to manage them, through fire fighting training. Class B fires should be extinguished using a foam or powder fire extinguisher, and can be prevented by ensuring proper storage, treatment and care for any and all potentially flammable liquids. In fire fighting training you will learn that it is necessary to keep, use and store all of these liquids far away from any potential igniters.
In fire fighting training, you will learn that Class C fires refer to gas fires and can be incredibly dangerous, involving gases such as propane, LPG or natural gasses. When it comes to gas fires, the primary way to put them out is to cut off the main supply of gas, and then to extinguish any remaining fire using a dry powder extinguisher. You can avoid gas fires, however, by ensuring that any gasses are stored in sealed and appropriate containers, within a safe storing area, and that any time these gasses do need to be used, they are used by trained professionals who are equipped with the necessary knowledge needed when it comes to gas fires.
Class D fires refer to fires that are caused by metals, which aren’t often thought to be flammable materials. However, some metals are indeed flammable, such as sodium, and can cause a fire to spread at a rapid rate. Even in a fire that wasn’t originally started by metal, if there is metal present at the scene of the fire it will melt under the high temperature and could cause sections of the building or support system to collapse as a result.
In fire fighting training, you will learn that attempting to use a water extinguisher on a metal fire, could actually accelerate the fire and worsen it. For that reason, there are often fire extinguishers developed for the sole purpose of extinguishing metal fires, and are usually equipped with dry powder which acts to smother the fire. If a metal fire occurs, you should always contact your local fire station or emergency services, but if the metal fire is fairly small and if you have immediate access to sand, then you can smother the fire by pouring the sand onto it
Class K fires generally refer to kitchen or cooking fires and often involve highly flammable substances. Class K fires are incredibly common and often occur in cramped kitchens where someone is working with extremely hot frying oil or any fats, which if exposed to a heat source such as the flame of the gas stove, can ignite. Because these fires occur within the confines of a kitchen, and occur using considerably fast accelerants, they can cause significant damage.
When a class K fire occurs, there’s a strong chance that other classes of fire could develop, especially class A fires because of the various materials usually found within a kitchen, including wooden cabinets and food cupboards. That is why these fires have the potential to wreak havoc on your home, and when they do occur you should use a wet chemical fire extinguisher, or if the fire is small enough, a fire blanket.
Types of fire extinguishers
When you begin fire fighting training at Emcare, you will also learn about the various fire extinguishers used in fighting fires, what specific classes of fire they are used to extinguish, and how you can go about identifying them from a first glance. Here are the various fire extinguishers commonly used in fire fighting training:
Foam fire extinguishers
Foam fire extinguishers contain a foam like substance that is best used to extinguish Class A and Class B fires and is found to be especially effective in extinguishing flammable liquid fires that involve diesel or petrol. Foam fire extinguishers achieve this by covering and sealing the surface of the liquid that is on fire. This prevents air from meeting with the substance, and effectively starves the fire.
Although, foam fire extinguishers should not be used on free-flowing liquid fires as it will not be effective in sealing off the fire. Foam extinguishers are incredibly common because of their ability to treat both Class A and B fires, and are known to be great at outing wood fires also. One can identify a foam fire extinguisher from its label, which in this case will have a CREAM in colour label.
Water fire extinguishers
Water fire extinguishers are another popular and common type of fire extinguisher because they seamlessly extinguish one of the most common types of fire, Class A fires. Class A fires, involving wood and paper materials, can spread quite rapidly, and using water extinguishers will ensure that you are thoroughly extinguishing the fire, but also that you are using a cost-effective method, with water extinguishers being one of the cheaper options. In fire fighting training, you will learn about the four main types of water extinguishers used: water spray, water jet, water with additives and water fog, which will all have a RED label.
- Water spray fire extinguisher: This fire extinguisher makes use of a fine spray of water droplets which cover the fire and are surrounded by non-conductive air. These extinguishers are tested on a 35 000-volt electrical source, from one meter, and therefore boast a 35kV dielectric test approval.
- Water jet fire extinguisher: These fire extinguishers use a powerful jet of water that is sprayed onto the fire, the intensity of which, immediately cools the burning substance and should stop the source from reigniting. Water jet fire extinguishers are popular options for managing Class A fires but should not be used on any live electrical equipment.
- Water with additives: These extinguishers contain water but have foaming chemicals added to them which enables the water mixture to thoroughly soak and absorb into the burning material, which assists in outing the fire. These extinguishers are also popular in instances where one does not have a lot of space to store a hefty fire extinguisher, and needs a smaller canister. This is because the smaller chemical water extinguisher can score the same fire rating as a water only extinguisher which tends to be larger.
- Water fog fire extinguisher: These extinguishers are sometimes called water mist instead of water fog and work to release a fine mist or fog of water, with incredibly small droplets, even more miniscule than those of a water spray extinguisher. These small droplets are effective at extinguishing fires because the small droplets have a large surface area in relation their size, which means that it will evaporate at a faster pace, which results in absorbing the surrounding heat at a faster pace, assisting in extinguishing the fire. The only shortfall of these extinguishers is that because the droplets are so small and weigh so little, they won’t come at the fire at the same force as a water spray extinguisher, so one would need to be fairly close to the fire for it to be effective.
Carbon dioxide fire extinguishers (CO2)
These fire extinguishers have a BLACK label and are best used for fires involving electrical equipment, which often occur inside of server rooms or spaces that contain a high amount of electrical equipment. These extinguishers can also be used on Class B fires and work by cutting off the air supply of the fire by smothering the fire. These extinguishers are unique in that they don’t leave behind any residue such as water, foam or powder.
Powder fire extinguishers
Powder fire extinguishers have a BLUE label and can be effective at extinguishing Class A, Class B and Class C fires. Although powder extinguishers can be used on electrical equipment, it should not be the first choice as they do not act to cool as well as smother so there is a chance that the electrical equipment could reignite. These are not recommended for use inside of a building because the powder reduces visibility and can make it difficult to breath.
Wet chemical fire extinguishers
Wet chemical fire extinguishers have a YELLOW label and are best used to extinguish Class K/F fires which involve cooking and flammable food substances such as oil and fats. These extinguishers are incredibly effective and can also be used to treat Class A fires as well as Class B fires. They work by releasing a wet chemical which simultaneously cools down the burning substance, outs the flames, and turns into a soapy solution which seals the surface of the fire and stops it from reigniting.
Fire blankets are commonly used in fires involving hot oil, so class F/K, but can also be effective at putting out a fire that is on someone, if their clothes are burning for example. Fire blankets smother the fire and thereby extinguish it.