When a fire breaks out, it can be terrifying. Your first instinct may be to grab the nearest extinguisher or hose and douse the fire with water. However, every fire is different, and certain extinguishers put certain fires out. However, while water effectively puts out some fires, using it on the wrong type of fire can spread the flames and worsen the situation. So what type of fire can you safely put out with water?
There are different types of fires, known as class A, B, C, and D fires. Many class A fires involve solid materials such as wood, paper, cloth, rubber, and some plastics. Water can be used safely to try to put out a class-A fire. This is because water extinguishes fire by removing heat.
When applied to a fire, water cools the fuel and helps prevent re-ignition. Water put on class A fire works by suffocating the fire. However, while water is ideal for class A fires, it should not be used on class B or C fires involving flammable liquids and electrical equipment.
So, in our guide, you can learn more about the different types of fire extinguishers that will put out what in the event of a fire. By the end, you’ll better understand the difference between a dry powder extinguisher to a wet chemical extinguisher, which fire extinguishers must be used, and when. (Read Stihl Chainsaw Chain Size Chart)
Different Types of Fire Extinguishers and Fires?
Fires are categorized into different classes based on the type of fuel involved. In addition, there is another class of fire extinguisher that goes along with this. Knowing the difference is vital so you don’t use the wrong type of fire extinguisher.
The main classes of fires are:
Class A Fires
Class A fires involve common solid materials like wood, paper, cloth, trash, and plastics. Class A fires are the most common type of fire. You should use an “A” labeled extinguisher containing either water or foam to put out a Class A fire.
Class B Fires
Class B fires involve flammable and combustible liquids like gasoline, oil, grease, tar, oil-based paints, solvents, and other flammable gases. Foam, dry chemical, and carbon dioxide (CO2) extinguishers labeled ‘B’ work best to put out a gas fire.
Class C Fires
Class C fires involve energized electrical equipment like wiring, fuse boxes, outlets, and appliances. These fires require non-conductive extinguishing agents. You would use a powder or carbon dioxide extinguisher to put out a Class C fire. In addition, it is dangerous to use water on a Class C fire as water can actually cause more harm and issues.
Class D Fires
Class D fires involve combustible metals like magnesium, sodium, aluminum, and potassium. Dry powder agents that do not react with the metal fuel should be used. Class D fire extinguishers contain these specialty agents. You should only use a dry powder extinguisher as this type of fire involves chemical reactions that could worsen if you put water on them.
Class K Fires
Class K fires involve cooking oils and grease commonly found in commercial kitchens. Wet chemical agents that coat the surface to prevent re-ignition work best. Class K extinguishers contain these agents. Like electrical fires, never use water on these fires. The main reason you can’t use water to put out fat fires is that it can quickly spread the fire once the water hits the hot oil.
- Water extinguishers: These put out fires by eliminating the heat source and shooting water onto the flames until the fire is smothered.
- Carbon Dioxide Extinguishers: These have a high-pressure mixture of gaseous and liquid carbon dioxide that suffocates the oxygen and starves the fire.
- Foam and Dry Powder Extinguishers: These both function similarly, with powder or foam extinguishers being filled with the respective compound to extinguish a fire.
- Multipurpose extinguishers are available for purchase and can put out typical home fires.
Can Class A Fire Be Put Out Safely with Water?
Class A fires involve ordinary combustibles like wood and paper. This is the most common fire you’ll encounter at home or in the office. The good news is that class-A fires can generally be safely extinguished with water. A simple water extinguisher cools the fuel source below its ignition temperature. Spraying water cools the fire and surrounding areas to prevent re-ignition. Using water also works by limiting the oxygen supply to the fire.
As water evaporates from the surface, it displaces oxygen in the air. With less oxygen, the fire eventually dies out. (Read Fire Pit Placement)
Can Class B Fires Be Put Out With Water?
Class B fires involve flammable liquids like oil, gasoline, paints, and solvents. **You should never try to extinguish a class B fire with water. These fuels float on water and will rapidly spread the flames. Using water on a gasoline or oil-based fire could cause an explosion hazard.
Instead, class B fires call for ‘B’ rated dry chemical, foam, or CO2 fire extinguishers. The foam coats the surface of the fuel, separating it from oxygen and smother the fire.
Is it Safe to Use Water on Class C Electrical Fires?
Electrical fires start from faulty wiring, shorts, or malfunctioning appliances. Using water to extinguish a class C electrical fire can be extremely dangerous. Water is the last thing to use on electrical fires. Water is an electrical conductor, and spraying water on an electrical fire can cause electrocution or serious shocks.
Can Water Be Used on Class D Metal Fires?
Class D extinguishers contain dry powder agents that smother the fire without reacting with the molten metal fuel. It is not safe to use water or foam on type D fires. Water and foam react violently when applied to burning metals. Only use extinguishers designed to put out this type of fire, such as a powder fire extinguisher.
Is it Okay to Use Water on a Class K Kitchen Fire?
Commercial cooking equipment is at high risk for oil and grease fires. Class K kitchen fires involve combustible cooking media like oils, fats, and grease. Do not attempt to extinguish a class K fire with water. Water will cause the burning grease to spatter and spread the flames. (Learn How To Turn Off Fire Alarm In Apartment)
What Fire Can Be Put Out With Water?
Water is an acceptable extinguishing agent on small, contained class A fires involving ordinary combustibles like wood, paper, fabrics, and trash. It works by cooling the fuel and displacing oxygen.
It is best to evacuate immediately and call emergency responders for larger, spreading structural fires. Improper use of water on certain fire types can make the situation more hazardous. Some key guidelines:
- Test any electrical equipment before spraying water on an electrical fire.
- Never use water on a class B flammable liquid or class D metal fire.
- Avoid using water on any energized electrical equipment.
- Do not attempt to extinguish large, spreading fires – evacuate the area.
Having the right type of extinguisher for the specific class of fire is crucial. Keeping combustibles away from ignition sources and following fire prevention tips can stop many fires before they start. But knowing when water can safely put out a fire or when to evacuate may help save lives.
How Do I Know Which Fire Extinguisher to Use?
Portable fire extinguishers are labeled with standard markings to indicate which types of fire they are designed to extinguish:
- Class A Extinguishers are filled with water or a dry chemical powder. Class A fires are the easiest to put out.
- Class B Extinguishers contain dry chemicals, foam, or CO2. Use for flammable liquid fires.
- Class C Extinguishers use non-conductive agents like CO2. Use for electrical fires.
- Class D Extinguishers have specialty dry powder agents for combustible metals.
- Class K Extinguishers contain wet chemicals for kitchen oil and grease fires.
What about car fires – can I use water?
If a vehicle catches fire, it’s best not to attempt putting out the fire yourself. Call emergency services and evacuate the area. Water could spread a gasoline-fueled car fire.
Is it better to use a fire hose or extinguisher on a house fire?
Only attempt to extinguish small, contained fires. Evacuate the building for any substantial or spreading structural fire, and call the fire department immediately. Never re-enter a burning building. (Read Should Lava Rocks Cover Burner)
What should I do if there is a fire in my kitchen?
If a fire does start, slide a lid over the pan to smother it, then turn off the heat source. For a spreading cooking oil/grease fire, evacuate and call 911 rather than trying to extinguish it yourself. Class K extinguishers or a fire blanket designed for kitchen fires are recommended.