Fires can occur anywhere – at home, in the office, in your car, or out in nature. When a fire breaks out, it’s crucial to act fast to extinguish it before it spreads out of control. Having the wrong type of fire extinguisher on hand or using the incorrect extinguishing agent can turn a controllable fire into a catastrophic emergency.
Water is actually one of the worst things you can use on certain types of fires! Yet many people’s instinct is to try dousing any blaze with water. This article will provide a helpful guide on the types of fires to be safely extinguished with water versus those where water should never be used.
Choosing the proper firefighting tool and technique for the specific class of fire will give you the best chance of putting it out quickly without making the situation worse.
In our guide, you can learn more about the different types of fire, and the different types of fire extinguishers to put out the certain types of fires. By the end, you’ll better understand what’s the easiest to put out a fire, what fire extinguishers contain, and the sort of fire the extinguisher can put out safely. (Learn How Much Wind Is Too Much For A Fire)
The 5 Classes of Fire
Here is a breakdown of what type of fire involves, and a quick look at what you can use in the event of a fire.
Class A Fires
The most common type of fire, many class A fires, involves ordinary combustibles like wood, paper, cloth, trash, and plastics.
You can use water to put out this kind of fire, as these fires are the easiest to control. Spray water can be used from a garden hose, bucket, or water and foam extinguisher sprayed directly on the burning material to extinguish a small type A fire.
For larger Class A fires, continuously drenching the fire with water or foam will cause it to run out of heat and fuel. The key is to use water on these fires at the base of the flames where the water-to-oxygen ratio increases. Here, the burning material is soaked, and water can actually prevent reignition. When using water to extinguish, or using a Class A fire extinguisher to extinguish a Class A fire, remove any smoldering debris once the fire is smothered.
Class B Fires
Class B fires involve flammable liquids like oil, gasoline, paints, tars, solvents, and other substances derived from petroleum. Though it may seem counterintuitive, never use water on a class B fire.
Oil and water don’t mix, and if you put water on such a fire, you can make things worse. The proper way to put out a Class B fire is to use a dry powder extinguisher or use a Class B fire extinguisher. This smothers the fire with a dry chemical.
You can also use a CO2 extinguisher, or sand to put out this type B fires if an extinguisher is unavailable. When a fire does start, it will also depend on the square footage of the fire.
Class C Fires
Electrical equipment fires are categorized as Class C fires. These types of fires originate from overheated wires, appliances, and other energized electrical sources. Like Class B fires, you cannot use water to extinguish burning electrical equipment!
Using water on a Class C fire can cause electrocution and shock hazards. To put out a Class C fire, use a CO2 or Class C dry chemical extinguishers that put out electrical fires. (Read Can You Burn Mulch)
Class D Fires
Class D fires involve combustible metals, including magnesium, sodium, titanium, and potassium, and so, you cannot use either water or foam.
These types of fires require a specialty powder or carbon dioxide extinguisher containing graphite, copper, and sodium chloride to extinguish a class D fire that doesn’t react with burning metal. Water should never be used on Class D fires as it can create explosive reactions.
Class K Fires
Class K fires involve cooking oils and greases like animal fats and vegetable fats commonly found in commercial kitchens. Though such fires can theoretically be extinguished with water if applied gently, water is not recommended, since it can cause splattering or explosion of super-heated grease. Special Class K wet chemical extinguishers are formulated for when a kitchen catches fire.
What Are The Types Of Fire Extinguishers?
The most common types of fire extinguishers include:
- Water extinguishers – Use pressurized water to extinguish small Class A fires involving ordinary combustibles like wood, paper, cloth, trash, and plastics. The water cools the fire and removes its heat.
- Foam extinguishers – Foam expands and smothers Class A and B fires by preventing oxygen from reaching the fuel. Good for quickly covering large areas with foam. Effective on wood, paper, cloth, and flammable liquids like gasoline or oil.
- Dry chemical extinguishers – Use powder to interrupt the chemical reaction of the fire. The powder also removes heat and oxygen. Works on Class B flammable liquid fires and Class C electrical fires.
- CO2 (carbon dioxide) extinguishers – CO2 displaces oxygen and absorbs heat from the fire. Does not damage electronics. Used for Class B and C fires.
- Wet chemical extinguishers – Designed for commercial kitchens. Suppresses fire through cooling and forming a soap-like solution. Used on cooking oil and grease fires.
- Dry powder extinguishers – Contain specific agents for extinguishing reactive Class D combustible metal fires. Prevent chemical reactions.
The right type of extinguisher must be matched to the proper class of fire to be effective and safe to use.
Can You Put Out a Gas Fire With Water?
If you have a gas fire, never attempt to put out with water. Water will not extinguish gas fuel and can cause the flames to rapidly spread and get out of control. If you have a gas fire, immediately turn off the fuel source if safe to do so. Evacuate from the area and call emergency responders. Use a Class B dry chemical fire extinguisher to safely put out the fire.
What Type Of Fire Can Be Put Out Safely With Water?
Class A fires are the most common and can be extinguished safely using water or a fire blanket if the fire is small. The key is to douse the fire completely and continue cooling it with water to prevent reignition.
How Does Carbon Dioxide Extinguish A Fire?
Carbon dioxide (CO2) extinguishes fire primarily by displacing oxygen, removing a key element needed for combustion.
It also absorbs heat from the fire and helps cool hot surfaces and gases near the flames. CO2 is effective at reaching into small spaces because it is a gas. Since it leaves no residue, CO2 extinguishers are a good choice for electronics and aircraft fires. It extinguishes flames by replacing oxygen with CO2 through suffocation. (Learn How To Connect A Wood Furnace To Existing Ductwork)
How Do You Extinguish A Class C Fire?
To safely extinguish a Class C electrical fire, use a carbon dioxide or dry chemical extinguisher designed specifically for electrical fires. CO2 and dry chemical agents will not conduct electricity like water does, preventing electrocution.
Turn off power to equipment at the breaker if possible. Then apply the CO2 or dry chemical agent in short bursts aimed at the base of flames until the fire is fully extinguished. Never use water on energized electrical equipment because of shock hazard. Class C electrical fires require a CO2 or dry chemical extinguisher.
How Are Class D Fires Usually Extinguished?
Specialty dry powder extinguishers containing agents like graphite, copper, or sodium chloride are typically used to extinguish Class D metal fires safely. Specific dry agents are needed that do not react with the burning metal to produce explosive byproducts. Only specially trained personnel should attempt to extinguish active metal fires, being sure to wear proper breathing and burn protection. Class D fires have unique risks requiring specific dry powder agents and training.
Does Water Put Out Rubber Fire?
No, water should never be used to try to extinguish burning rubber, plastics, or other types of petroleum-based fires. Adding water can cause splattering or boiling over of the burning material, spreading the fire.
Instead use a Class B dry chemical, carbon dioxide, or foam extinguisher. These smother the fire by displacing oxygen. Water will not properly extinguish burning rubber, plastics, or other fuels classified as Class B flammable liquids. (Read What Happens If You Shoot A Propane Tank)
Knowing how to respond to a fire emergency and match the proper extinguisher to the type of fire can save lives and property. Though water extinguishers work on ordinary combustible fires, they should never be used on every fire such as electrical or flammable liquid fires which can spread the flames.
Extinguishing a fire safely requires using the right extinguishing agent for the specific class of fire involved. Fire can be a helpful tool or a destructive danger depending on how it is handled.