The mention of fire paints different images to every single person, this is because fire is both one of the greatest tools and the most destructive force. As it is important to prevent fire from becoming a destructive force, it is also more important to put in place a plan to deal with such an occurrence. One needs to first understand that all fires are not the same and the best approach for each type of fire.
Fire extinguishers are classified by the type of fires they are designed to extinguish. There are five basic classes of fire and fire extinguishers.
The Different Classes of Fire
Class A Fires
Class A fires are fires involve solid combustible materials like paper, wood, fabric, plastic and trash. They are the most common of the five fire classes and are prone to occur in all industries, homes and offices. They are very dangerous because they can intensify quickly if there is an abundance of fuel. They are best extinguished with water and monoammonium phosphate.
Class B Fires
Class B fires involve liquids like alcohol, gasoline, kerosene and gasses like propane, butane. This class of fires is also prone to occur across all industries, homes. The best way to extinguish class B fires is by smothering them or by removing oxygen from them using CO2 or Foam extinguishers.
Class C Fires
Class C fires include all fires that are caused by electrical failures, faulty wiring and shortages. This type of fires are highly prone in facilities that make use of heavy electrical equipment but are prone across all industries. Water is a dangerous choice when dealing with class C fires since it can conduct electricity causing shock, the best remedy to this class of fires is disconnecting from the main power supply. However, to reduce the intensity of the fire, foam and clean agent suppressing extinguishers are best.
Class D Fires
Class D fires involve flammable metals like titanium, aluminum, magnesium, and potassium. This Class of fires is mainly prone in laboratories. They are best extinguished using dry powder agents for their smothering properties.
Class K Fires
Just like Class B fires, Class K fires are caused by flammable liquids. However, Class K fires are specifically caused by cooking flammable liquids like Grease, oil, Vegetable oils and animal fats. They are best extinguished by smothering the flames or using a wet agent fire extinguisher.
Types of Fire Extinguishers and their Uses
Water Fire Extinguishers
Water extinguishers contain only water, for this reason they are the most affordable and easiest extinguishers to maintain. They extinguish fire by absorbing the heat from the burning object. Water extinguishers, red labeled, are mainly found in homes, offices, schools, shops and warehouses. They are only used for Class A fires.
Water Mist Extinguishers
Water Mist extinguishers contain demineralized water particles, they are more expensive than water extinguishers. They work by cooling the fire and reducing the oxygen supply. They are suitable for Class A, B, C and K fires, some Water mist extinguishers are also suitable for electrical fires on equipment of up to 1000volts. For their safe and effective use on all classes of fire, they are quickly replacing water extinguishers.
Foam extinguishers contain water, foam concentrate and air which when mixed in correct proportions form a homogeneous foam blanket. Foam smothers the fire in solids and liquid therefore suitable for Class A and B fires, however, not suitable for Class K fires. The drawback on foam extinguishers is that they leave a residue that has to be cleaned and are more expensive than water extinguishers.
Dry Powder Extinguishers
Dry powder extinguishers highly contain monoammonium phosphate and Nitrogen used to pressurize the extinguishers. They work by the powder forming a crust which smothers the fire and stops it from spreading. However, the powder does not soak into materials and does not have an effective cooling effect on the fire, which can result in the fire reigniting, powder is hazardous if inhaled, so they should be used in well-ventilated areas and are not suitable for offices and domestic premises and needs a lot of cleaning up after use. They are suitable for Class A, B, C fires.
CO2 extinguishers contain pressurized carbon dioxide gas only. They are suitable for Class B and C fires. CO2 works by suffocating the fire and does not cause damage to the electrical items or cause the system to short circuit. However, CO2 extinguishers get very cold during discharge, and those that are not fitted with double-lined, frost-free swivel horns may cause fingers to freeze to the horn during deployment. They can asphyxiate in confined spaces, and they are not suitable for deep fat fryers, because the strong jet from the extinguisher can carry the burning fat out of the fryer. They do not offer post-fire security since once the CO2 has dissipated into the atmosphere, fires can quickly re-ignite.
Wet Chemical Extinguishers
Wet Chemical extinguishers consist of a pressurized solution of alkali salts in water, which, when operated, creates a fine mist, cooling the flames and preventing splashing. For this reason, apart from Water Mist Extinguishers, suitable for Class K extinguishers.
Now that you know the classes of fire and the suitable extinguishers for each class of fire, do you know how to effectively deploy your fire extinguisher? The acronym PASS has been widely used to describe the four basic steps of using the modern portable extinguishers.
- Pull (Pin)
Pull pin at the top of the extinguisher to break the seal. When in place, the pin keeps the handle from being pressed and accidentally operating the extinguisher. Immediately test the extinguisher, Aiming away from the operator, to ensure the extinguisher works and also show the operator how far the stream travels
Approach the fire standing at a safe distance. Aim the nozzle or outlet towards the base of the fire.
Squeeze the handles together to discharge the extinguishing agent inside. Release the handles to stop discharge,
Sweep the nozzle from side to side as you approach the fire, directing the extinguishing agent at the base of the flames. After a Class A fire is extinguished, probe for smoldering hot spots that could reignite the fuel.