A water fire extinguisher is one of the most common types of fire extinguishers, designed specifically for tackling Class A fires. These fires involve ordinary combustible materials such as wood, paper and fabric.
How Does a Water Fire Extinguisher Work?
There are three components that are needed for an ignited fire to continue to burn. These are oxygen, fuel, and heat – together known as the fire triangle. If you take away one of these components, then the fire will be extinguished.
Which leads us to water extinguishers. They work by discharging a jet of water at high pressure to cool down flames and burning surfaces, thereby removing the heat component to extinguish the fire and prevent it from reigniting. Unlike powder fire extinguishers, water extinguishers do not leave behind any residue, as water is the extinguishing agent, which allows for an easier post-fire clean-up process.
Types of Water Fire Extinguishers
There are three main types of water fire extinguishers:
- Jet water extinguishers: These release a powerful stream of demineralised water and are effective for deep-seated Class A fires.
- Water spray extinguishers: These discharge a fine mist of water droplets, rapidly covering a large surface area to cause a blanketing effect that both cools and reduces oxygen to the flames.
- Water additive extinguishers: Also known as hydrospray extinguishers, these contain a mixture of water and chemical additives that remove the water’s surface tension, thereby making the sprayed water ‘stickier’ so that it adheres to burning surfaces more effectively.
Where Should Water Fire Extinguishers Be Used?
Water fire extinguishers are best suited for locations with a high presence of combustible materials. Common places where they are installed include:
- Offices and commercial buildings
- Schools and educational institutions
- Warehouses and storage facilities
- Public buildings
- Residential properties
When Should You Not Use a Water Fire Extinguisher?
Despite their effectiveness for Class A fires, water fire extinguishers should never be used on certain types of fires, including:
- Class B fires caused by flammable liquids: Water is the absolute worst thing to try to put out such a fire, as it will vaporise into steam and spit out the flammable liquid, worsening the fire.
- Class C gas fires: Water is ineffective against gas fires.
- Class F fires caused by cooking oil: Water reacts violently with hot oils, potentially causing dangerous fire flare-ups that spread the fire and put lives at risk.
- Electrical fires: Water conducts electricity and could cause electrocution when used on electrical fires.
Maintenance and Regulations
Regular maintenance and servicing of water fire extinguishers are essential to ensure their effectiveness. Businesses and property owners should adhere to fire safety regulations, conducting routine checks and annual servicing by a qualified professional.
