Are you looking for a fire extinguisher for your kitchen? Whether at home or in a professional kitchen, wet chemical fire extinguishers will help you keep your kitchen safe from fires related to cooking oils, lard, fats, and olive oils, among others.
You can also use the extinguishers for class A fires involving flammable solids such as paper, textiles, plastics, and wood. Even better, some brands are ideal for class B fires caused by flammable liquids such as petrol, kerosene, paint, and diesel, among others. Like all other fire extinguishers, you need training on how to use the extinguishers effectively. Read on to learn more.
What is a Wet Chemical Fire Extinguisher?
Also known as class F fire extinguishers or ABF fire extinguishers, wet chemical fire extinguishers contain potassium as the extinguishing element. It releases the potassium as a fine mist covering the cooking oils’ surface to extinguish a fire. The extinguishers feature a YELLOW-colored label on their bodies that reads WET CHEMICAL. It features a relatively long hose with a lance attachment, making it safer. Because hot oil tends to pop, the long hose keeps you safe so it doesn’t land on your face or hands.
You can use the extinguisher on all premises that fry foods. These include a home kitchen, burger bar, restaurant, hotel, and workplace kitchen. It is effective in fighting class A and class F fires. These wet chemical fire extinguishers are in classification K. The “K” classification suits them for commercial cooking appliances like deep-fat fryers. However, because the potassium in them is electrically conductive, users require training to use them to avoid electrical accidents. It also means you must switch off the appliances before using the fire extinguishers.
Wet chemical fire extinguishers are the only ones effective against cooking oil. Other extinguishers, such as water, foam, powder, and CO2, will aggravate cooking oil fires. When hot oil comes into contact with other substances, such as water, it sizzles and pops.
Unless the wet chemical extinguisher is cleared for use on class B fires, always assume that the extinguisher only puts out class F fires.
How Do Wet Chemical Fire Extinguishers Work?
Wet chemical fire extinguishers contain potassium acetate, potassium citrate, and potassium carbonate. These potassium salts come out as a fine mist that creates a soapy layer when they land on the surface of the hot cooking oils. This soapy layer creates a cooling effect that smothers the fire. The soapy layer also acts as a barrier when it coats the surface of the oil, so splashes will not get to you.
The light nature of the mist ensures that the fat does not splash. Again, potassium does not react with the fat, so sizzling and popping do not occur.
Advantages and Limitations of Wet Chemical Fire Extinguishers
Pros
- Fast Action: Wet chemical fire extinguishers release a fine mist that instantly cools the surface of the cooling oil and creates a barrier.
- No Re-Ignition: The fine mist from the extinguisher leaves a soapy barrier on the cooking oil’s surface, preventing re-ignition.
- Low Pressure: Wet chemical extinguishers release a fine mist at low pressure, ensuring no splashes or injuries to the user.
- Easy Cleanup: Although the extinguisher leaves residue behind, it is easier to clean than a dry chemical powder extinguisher. You will not use the cooking fat after extinguishing the fire, as the potassium is unsafe for human use.
- Long Hose: Wet chemical fire extinguishers have relatively long hoses. This allows you to use them from a safe distance to protect you from injuries in the event of a splash.
- Class F Fires: This is the only extinguisher for cooking oil fires.
Cons
- Corrosive Residue: The substance inside wet chemical fire extinguishers is alkaline. If left to sit on metals after putting out a fire, the substance can corrode aluminium and other metals. As such, you need to clean it up immediately.
- Chemical Mist Irritates Eyes and Skin: You need to be safe from the sprayed mist as it can irritate the eyes and skin, causing discomfort. If the mist comes into contact with your skin, clean it immediately.
- Not Suitable for Electrical Fires: Potassium is a conductive material. As such, it will aggravate the fire and increase the risk of electric shock when used for electrical fires.
- Toxic Fumes: The fumes from wet chemical fire extinguishers poison cooking oils. During use, be careful not to spray the mist on food items. Open the windows and door to ventilate the kitchen after use.
How To Use a Wet Chemical Fire Extinguisher
Wet chemical fire extinguishers feature an extended applicator. During use, move the hose in slow circular movements to gently apply the fine mist in spray form. The mist comes out under low pressure to cover the surface of the burning cooking oil, emulsify it, and cool it.
Hold the extinguisher and aim the applicator tip at the burning oil to put out a fire. The tip needs to be at least a meter from the burning oil. Squeeze the lever and move the applicator in circles around the base of the fire. Here is a step-by-step procedure:
- Turn off the deep fat fryer to reduce the risk of an electric shock. Potassium is conductive and should not come into contact with electricity.
- Hold the applicator of the extinguisher at arm’s length and let the nozzle sit about a meter from the base of the fire.
- Remove the pin and squeeze the lever so the fine mist falls gently on the burning cooking oil.
- Spray the entire contents of your extinguisher, even if the fire goes out quickly. This allows the mist to create a barrier that ensures no re-ignition risk.
To keep wet chemical fire extinguishers, you need to have a professional inspect them every twelve months. However, if your environment has more fire hazards than standard, you should inspect the extinguisher every six months. After five years, wet chemical extinguishers require a hydrostatic pressure test. The test checks the extinguisher’s effectiveness and the chemical’s condition inside the cylinder. You also need to recharge the extinguisher after discharging it. After a recharge, wet chemicals need testing every three years.
Wet chemical extinguishers may need to bear a tag showing the last inspection date. After a recharge, do not place the extinguishers in extremely cold areas.
Wet chemical fire extinguishers can last up to ten years for home use. However, you need to check them regularly to ensure that:
- The pressure level is as recommended
- The nozzle has no obstruction
- The pin and tamper seal is intact
- No leaks
- Has no dent
- No rust that can affect the performance of the cylinder
- No signs of wear
- No chemical deposits on the cylinder
After use, you need to clean up to prevent the corrosion of parts. The wet chemical from the extinguisher can irritate your skin. As such, wear protective goggles and gloves to protect your eyes and skin. Soak up the residue with wet paper towels or pieces of cloth and remove it. Wash the affected area with warm water until you remove all residue. Soak up any remaining residue as you wipe the surface. After the cleanup, dispose of the paper towels or cloth as normal waste.
When using wet chemical fire extinguishers, you need to watch out for the following:
- Corrosion: Do not leave the wet chemical on metal surfaces for long, which could cause corrosion.
- Irritation: Wash off any wet chemical that falls on your skin to prevent skin irritation. If irritation persists even after washing your skin, seek medical attention.
- Disposal: The wet chemical is unsafe to dispose of down the drain as it can corrode some metals.
You will need to refill and recharge wet chemical fire extinguishers every five years. If you last used the extinguisher five years ago, discharge it and recharge it. You need to let a professional trained in handling pressurized chemicals discharge and recharge the extinguisher. If the recharge is not well-handled, the extinguisher could malfunction when needed. The refill process goes as follows:
- Discharge the extinguisher into a discharge bag.
- Remove the hose and valve and clean them with a soft cloth. Use a solvent-free cleanser to remove the dirt on the sides of the cylinder. Solvent-based products can damage the plastic parts of the pressure gauge.
- Repair or replace damaged parts of the extinguisher. Abrasions, dings, rust, welding damages, and other damages can affect the extinguisher’s effectiveness.
- Fill the cylinder with wet chemicals as specified on the label using a funnel.
- Re-pressurize the extinguisher and test if it meets the recommended pressure level.
- Reconnect the extinguisher hose and connect the pin
- Weigh the cylinder
You can drop off the wet chemical extinguisher at the local fire department at the end of its functional life. The cylinder is a dangerous good and should not be part of your household waste collection.
Wet Chemical vs Other Fire Extinguisher Types
Wet chemical fire extinguishers only fight class A and F fires. If your premises are at risk of fire outbreaks from different fuel sources, you might need one or two other fire extinguishers. Having a suitable fire extinguisher is essential to meeting fire safety regulations.
To pick the suitable fire extinguisher, you need to understand the different classes of fire as follows:
- Class A fires that involve combustible solids such as wood, textiles, paper, and plastics
- Class B fires result from flammable liquids such as petrol, diesel, paint, turpentine, and kerosene, among others
- Class C fires that result from flammable gases such as methane and butane
- Class D fires that result from combustible metals such as potassium
- Class F fires caused by cooking oils
- Electrical fires that involve electrical equipment
Depending on the type of fire you want to extinguish, you can choose between five types of extinguishers:
Foam Extinguishers
These extinguishers put out class B fires. They are water–based and most effective in fighting class A fires. The extinguishers feature a cream-colored label and work by creating a cooling effect on the fuel that causes a fire. Spraying on a fire creates a barrier between the fuel source and the flame. The extinguisher comes in handy in buildings that feature many organic materials, such as warehouses, hospitals, schools, and residential properties. It also works for premises that store flammable liquids such as petrol and diesel. Place the extinguisher near exits that pose a risk for class A and B fires.
Water Extinguishers
You can use water extinguishers for class-A fires. The extinguisher features a bright red label and works to prevent fires caused by organic materials such as textiles, cardboard, coal, wood, paper, and plastics, among others. You should never use them for fires caused by flammable liquids, oils, or electricity.
The water fire extinguisher works by cooling the heat from the fire. You should place them on exits with risks for class A fires.
Some water fire extinguishers may have a spray nozzle. The spray nozzle allows the water to cover a larger area faster than a jet nozzle. You can also go for water mist fire extinguishers that release water in mist. They have a unique nozzle that releases microscopic mist that reduces the oxygen in the air to suffocate a fire and cool the surface of a fire.
Dry Powder Extinguishers
Also known as ABC fire extinguishers, these units have a blue label. They are ideal for fighting class A, B, and C fires. They feature mono ammonium phosphate as the main extinguishing chemical. During use, the powder creates a blanket on top of the fire, suffocating it. The powder is not ideal for indoor use, as inhaling it is risky. After use, the residue requires immediate cleaning as it can harden if left for too long. You can also use the extinguishers for electrical fires in appliances rated 1000v or lower.
There are specialist dry powder fire extinguishers that you can use to put out metal-related fires – one for lithium-ion fires and another for all other metal fires. It is ideal for garage forecourts, welding businesses, and premises with many flammable organic materials, liquids, and gases.
Carbon Dioxide (CO2) Fire Extinguishers
CO2 fire extinguishers are ideal for electrical fires. They smother a fire by reducing oxygen to suffocate the fire. You can use these extinguishers in computer server rooms. Besides electrical fires, these extinguishers effectively put out class B fires involving flammable liquids. It features a black label.
Frequently Asked Questions (FAQs)
Can I use a wet chemical fire extinguisher on an electrical fire?
No. You should never use water, foam, or wet chemical extinguishers to extinguish an electrical fire. These substances can conduct electricity and increase the risk of an electric shock. Instead, use a CO2 fire extinguisher for all electrical fires or a powder fire extinguisher for electrical equipment rated 1000v or lower. Only wet chemical fire extinguishers are used for cooking oil fires and class B fires.
Is a wet chemical extinguisher safe to use in confined spaces?
You can use wet chemical fire extinguishers in a confined space. The cylinder releases the wet chemical under low pressure, meaning there is no risk of the chemical coming into contact with your skin. Even better, the extinguishers have a long hose which allows you to use them at arm’s length. However, after discharging the extinguisher, you must ventilate a room to release the poisonous fumes. If the fumes come into contact with your skin or your eyes, you must wash it off immediately to avoid irritation.
Can I recharge a wet chemical fire extinguisher after use?
Recharging a wet chemical fire extinguisher is best left to professionals trained in handling pressurized chemicals. Even if the process is simple, you should let a professional do it. A recharge comes in handy after use and after five years of no service. A professional will check the cylinder to ensure it has the necessary pressure and that the nozzle and hose are free of obstructions. If you choose to recharge the extinguisher at home, you need the owner’s manual. The manual guides you through the weight of the chemical to use and the recharge process.
Conclusion
Wet chemical fire extinguishers release dangerous fumes. As such, you need to get the necessary training from a professional before you use these extinguishers. Using these extinguishers is pretty standard – pull the pin, aim the nozzle, squeeze the lever, and sweep side to side. Even though the process is simple, training comes in handy to help you stay safe when putting out a fire. The professional will advise you on the precautions to observe during use and the best way to prevent re-ignition.
Further, picking the right location and size of the wet chemical extinguisher will enhance its effectiveness. Place an extinguisher near an exit identified as high risk for cooking oil fires. The size of the extinguisher you choose should match the size of your kitchen. For large commercial kitchens, a 6kg cylinder will come in handy. For a home kitchen, a 2kg cylinder will suffice.