How Do Water Fire Extinguishers Work?
Water fire extinguishers contain AFFF (Aqueous Film Forming Foam) extinguishing agent and nitrogen gas as the pressurizing medium. When discharged, the extinguisher releases a fine foam that spreads across the surface of the burning material. As the foam settles, it releases water that forms a thin film over the flammable surface, effectively cutting off the oxygen supply, and stopping the combustion process.
Advantages of Water Fire Extinguisher
- Effective Physical Fire Suppression
Emerging in the 1980s, water fire extinguishers utilize a physical extinguishing mechanism. The agent forms a thin water film on the surface of burning materials, isolating them from air and suppressing the fire. The atomizing nozzle disperses fine water mist throughout the fire zone, which absorbs heat, rapidly lowers the temperature, and reduces oxygen concentration in the combustion area—helping to prevent re-ignition. Their superior anti-re-ignition capability is one of their most remarkable advantages. Fire Scene Self-Protection
Besides fire suppression, water-based extinguishers can be used for personal protection during a fire. In emergencies, individuals can spray the agent onto their bodies and heads, shielding themselves from flames and minimizing burn injuries in high-temperature environments.Convenient and Safe Operation
Water-based fire extinguishers do not need to be inverted during use. They have a long service life, excellent anti-reignition capability, dual extinguishing action (foam and cooling), and leave no residue or contamination on equipment. Their minimal corrosiveness makes them ideal for use around precision instruments and sensitive equipment.
Limitations of Water Fire Extinguishers
- Heavier Weight
Water-based fire extinguishers are generally heavier compared to dry powder extinguishers, which may make them slightly more challenging to carry. - Shorter Shelf Life
While some dry powder extinguishers can be stored for up to 10 years, the maximum shelf life of water-based extinguishers is typically around 6 years.
Higher Cost
The price of water-based fire extinguishers is generally higher than that of traditional dry powder extinguishers due to the materials and technology used.
Suitable Applications
Water fire extinguishers are ideal for initial stage fires and provide effective suppression while minimizing the risk of reignition. They are suitable for:
Fires involving solid materials such as wood, fabric, and paper.
Fires involving flammable liquids like gasoline or volatile chemicals.
Fires involving electrical equipment and kitchen grease fires.
Additionally, water-based fire extinguishers can be used both indoors and outdoors, even under windy conditions. They are highly versatile and suitable for residential homes, vehicles, commercial offices, factories, and more.
Proper Usage of Portable Water Fire Extinguishers
For optimal performance, it is best for one person to operate a portable extinguisher:
Carry the extinguisher by its handle to the fire scene and stop approximately 5 meters from the fire. If outdoors, approach from the upwind direction.
Set the extinguisher down and remove the safety pin (avoid pointing the nozzle towards anyone during this step).
Hold the front end of the hose with one hand and press down firmly on the operating handle with the other.
The extinguishing agent will spray from the nozzle and should be directed toward the base of the flames.
Special Techniques for Different Fire Types:
For Spilled Liquid Fires: Approach from the side of the flame and aim at the base, sweeping from near to far, moving quickly side-to-side until the fire is completely suppressed.
For Container Liquid Fires: Approach from the side, aim at the flame base, and sweep across. Avoid spraying directly onto the liquid surface to prevent splashing and worsening the fire.
For Solid Material Fires: Aim at the most intense flames and sweep side-to-side, ensuring even coverage across the burning surface until fully extinguished.
During operation, the extinguisher must always remain upright to ensure continuous spray. Do not tilt or invert it while in use.
Operating Procedures for Wheeled Water Fire Extinguishers in Large Fires
For larger fires, wheeled water fire extinguishers require a coordinated two-person operation to ensure effective and safe firefighting. The following steps outline the detailed procedure:
Transporting the Extinguisher to the Fire Scene
Both operators should move the water fire extinguisher quickly but cautiously to the fire location, ensuring stability during transit.
Stop approximately 15 meters (50 feet) away from the fire to maintain a safe distance while preparing for extinguishment.
If outdoors, always approach from the upwind direction to prevent smoke and flames from blowing toward the operators, improving visibility and safety.
Hose Deployment
One operator (Hose Operator) unrolls the hose completely, ensuring it is straight and free of kinks or twists to allow smooth water flow.
Check for any obstructions or sharp objects that could damage the hose.
Maintain a firm grip on the hose near the nozzle to control direction once water is released.
3.Assessing Stance and Aiming
- The Hose Operator should adopt a stable stance, standing sideways to the fire with feet shoulder-width apart for balance.
- Grip the spray gun firmly with both hands (one hand on the trigger, the other supporting the nozzle) to manage recoil when water is discharged.
- Aim the nozzle at the base of the flames (the fuel source) rather than the tops of the flames to maximize extinguishing efficiency.
4. Activating the Water Fire Extinguisher
- The second operator (Valve Operator) moves to the extinguisher’s main valve and waits for confirmation from the Hose Operator before opening it.
- Once ready, the Valve Operator fully opens the valve in a smooth motion to start the water spray.
- Monitor water pressure and adjust if necessary to maintain a steady, controlled stream.
5. Extinguishing the Fire
The Hose Operator should use a sweeping motion at the fire’s base, moving side to side to cover the entire burning area.
If the fire begins to spread or intensify, both operators should retreat to a safe distance and reassess before continuing.
After extinguishing the fire, the Valve Operator should close the valve while the Hose Operator relieves pressure from the hose.
6. Operation Safety Check
Inspect the area for remaining hotspots or re-ignition risks.
Once the fire is fully extinguished, properly recoil the hose and secure the extinguisher for future use.