When it comes to combating fires in professional kitchens, the wet chemical fire extinguisher is the gold standard. Designed specifically to handle cooking oil fires, this type of extinguisher is an indispensable safety tool in any commercial kitchen setting.
How Do Wet Chemicals Extinguish a Fire?
In the fire safety industry, wet chemical fire extinguishers are a relatively recent innovation, developed to address one of the most common causes of accidental fires—cooking appliances. Both at home and in workplaces, deep fat fryers and other cooking equipment are leading sources of fires. Wet chemical extinguishers have proven to be among the most effective solutions for tackling fires caused by burning oils and fats.
Wet chemical extinguishers work primarily through two mechanisms: cooling and emulsification. When the extinguisher is discharged onto a burning oil or fat fire, the chemical cools the surface temperature of the oil, lowering it below its ignition point. Simultaneously, it creates a soapy layer (a process called saponification) that seals the surface, cutting off the oxygen supply and preventing re-ignition. This dual action effectively stops the fire from reigniting.
Wet chemical fire extinguishers are typically rated for both Class A (combustible materials like wood, paper, and textiles) and Class F (cooking oils and fats) fires, making them versatile for use in kitchens and food preparation areas.
The Science Behind Wet Chemical Fire Extinguishers
A fire needs three elements to ignite and sustain itself: heat, fuel, and oxygen—often referred to as the fire triangle. If any one of these elements is removed, the fire will be extinguished. Wet chemical extinguishers target both heat and oxygen simultaneously. By cooling the burning material and forming a barrier that blocks oxygen, the wet chemical breaks the fire triangle, effectively putting out the fire.
Where Can Wet Chemical Fire Extinguishers Be Used?
The wet chemical fire extinguisher is highly effective against several classes of fire:
Class F Fires: Fires involving cooking oils and fats such as lard, olive oil, vegetable oil, and similar substances.
Class A Fires: Fires fueled by flammable solids like wood, textiles, and paper.
Class B Fires (Limited Use): Some wet chemical fire extinguishers are approved for use on fires involving flammable liquids like paint, diesel, and petrol. Always check the extinguisher’s label or consult a fire safety professional to ensure its suitability.
Where Should Wet Chemical Fire Extinguishers Not Be Used?
Despite its versatility, the wet chemical fire extinguisher should not be used in the following scenarios:
Class B Fires: Unless specified, wet chemical extinguishers are generally not suitable for these fires.
Class C Fires: Fires involving flammable gases such as butane and methane.
Electrical Fires: Wet chemical extinguishers are not designed to handle electrical fires.
How to Identify a Wet Chemical Fire Extinguisher
Identifying a wet chemical fire extinguisher is straightforward:
Label Color: Look for a yellow label that reads “WET CHEMICAL.”
Hose and Lance: The extinguisher features a longer hose with a lance attachment for precise application.
ID Signage: Nearby signage will indicate “WET CHEMICAL EXTINGUISHER.”
Alternative Names for Wet Chemical Fire Extinguishers
The wet chemical fire extinguisher is also known as:
Class F Fire Extinguisher
Class ABF Fire Extinguisher (for certain models that can handle multiple fire classes)
How Does a Wet Chemical Fire Extinguisher Work?
Wet chemical fire extinguishers use potassium salts, which are discharged as a fine mist. This mist reacts with the burning oil to create a soapy layer, effectively smothering the fire and preventing re-ignition. The fine mist also cools the fire and minimizes the risk of spreading the burning oil.
Pros and Cons of Wet Chemical Fire Extinguishers
Pros:
The only extinguisher specifically designed for cooking oil and fat fires.
Cons:
May release toxic fumes, so the area must be ventilated after use.
Who Needs Wet Chemical Fire Extinguishers?
Any establishment with professional cooking equipment should have a wet chemical fire extinguisher, including:
Hotel kitchens
Restaurants
Burger bars
Fish and chip shops
How to Use Safely
Using a wet chemical fire extinguisher requires caution to avoid splashing burning oil. Follow these steps:
Pull the safety pin to break the anti-tamper seal.
Stand at a safe distance from the fire.
If safe, turn off the heat source.
Hold the lance at arm’s length, keeping the nozzle at least 1 meter above the flames.
Spray in a circular motion to allow the foam to settle and form a sealing layer over the fire.
Discharge the full contents to minimize the risk of re-ignition.