Not all fire extinguishers are created equal. There are many different categories of fire and with that, at least as many extinguishers to fight those fires. This article will examine fire sources by category, introduce a few different specialty extinguishers, what kinds of fires they best control, identify their limitations and reveal recommended extinguisher types.
The categories are grouped by what is being burned.
Class A – These fires involve solid materials, like wood furniture, drapes, plastic
Class B – Refers to combustible liquids, gasoline, kerosine, solvents, paint
Class C – Refers to energized electrical equipment. Appliances, heaters.
Class D – Refers to combustible metals like magnesium, titanium, zirconium, sodium, lithium, and potassium and is usually something you see in commercial factory settings.
Class K – Refers to grease and oil fires.
Extinguishers on the Market.
Dry Chemical extinguishers, A, B, C – commonly referred is A, B, C Extinguishers are the most recommended for home use and are usually a mix of monoammonium phosphate and ammonium sulfate in a dry powder form. They are commonly red and have a pressure gauge.
Dry Chemical, Purple K Extinguishers B, C - is also a dry chemical, but it is, potassium bicarbonate based, which may react badly with phosphate-based extinguishers if used in conjunction. This chemical is for B and C-class fires and possibly may aid in a grease or K-class fire but is not made for class A fires.
Carbon dioxide and Halon Alternative Extinguishers, B, C - fight B and C class fires and is a clean gas, leaving no residue to clean up, like the other chemical. But is not generally thought to be as effective as the Purple K chemical and also comes out very cold and can cause harm to the skin, almost like dry ice. There are Halon gas alternatives that have come out that can also be effective on class A fires, making them a possible alternative to the ABC and can be better than the straight carbon dioxide extinguisher for B, and C class fires.
Wet Chemical, K Class extinguishers, K – these extinguishers suppress oil and grease well and are also effective on class A fires. The wet chemical, a low “pH” potassium acetate solution is a mist that creates a blanket of foam over the oil or grease suppressing the fire. These extinguishers are usually seen in commercial kitchens.
Water-based extinguishers with additives, A, some B – These extinguishers are generally less versatile than some of the others but are thought to be cleaner in some regard. These are primarily for Class A fires. Water-based units are not recommended for Class K, oil and grease or electrical fires as they could cause the fire to spread and even explode or act as a conductor. Some water-based extinguishers hitting the market claim to be more all-purpose including Class K, but there is conflicting data and we were unable to substantiate these claims or whether these units have gone through UL or similar testing. As stated above it is not a good idea to throw water on an oil or grease fire or electrical fire. The water-based extinguishers do have additives that aid in the suppression of fire and there may be newer additives and overall formulations that make these extinguishers more versatile but we have not been able to verify this.
Class D powder - Used specifically for combustible metals, and are usually powdered graphite, granular sodium chloride, or copper-based pressurized with Argon. Found in industrial settings.
Recommended for Every Home.
Let’s make it simple. The National Fire Prevention Association recommends that every household have at least 1, ABC extinguisher, preferably 1 on each floor, and should indicate testing by a testing laboratory like UL. The NFPA recommends at least a 2-A:10-B: C rated extinguisher for the home. Smaller 1-A:10-B: C units on the market do meet compliance standards but are generally recommended for portable use, cars boats, camping, etc. Note that ABC fire extinguishers commonly expire 12 years after the date of manufacturer.
What About Kitchen Grease and Oil Fires?
But what about the common Kitchen fire? Are we left under gunned by the ABC? Do I need a K-rated extinguisher? The truth is the ABC extinguisher will suppress at least temporarily an oil and grease fire that is not too large. It is about the heat. An A class fire, burning drapes, as an example, once the fire is out the drapes (the burning fuel) cool down rather quickly, but the typical oil and grease fire is very hot and the oil (the Burning fuel) remains hot for quite some time and can reignite again even after the fire is out, rendering the ABC extinguisher less effective. All that said, we don’t see recommendations for K-rated, wet chemical, units for residential use. Perhaps due to the damage that film/foam can do to the kitchen weighted against the unlikely event of a large-scale grease fire.
There are Some Other Safeguards.
Remember that fire needs, oxygen, heat, and fuel (something to burn) to ignite and maintain itself. A simple fire blanket can deprive the fire of it's needed oxygen and save you the use of an extinguisher or be used in conjunction with an extinguisher if needed (fire blankets have no expiration date). For these reasons, experts recommend fire blankets as a staple household safety item alongside your standard ABC extinguisher.
Plan for Safety
Andy, Senior Editor
Sources: NFPA.org, https://www.chemguard.com/fire-suppression/catalog/dry-chemicals/, https://www.netatmo.com/security-guide/home-fire-extinguisher, https://www.badgerfire.com/Pages/FireExtinguishers.aspx, https://www.consumerreports.org/home-garden/fire-extinguishers/buying-guide/, https://anchorsafetyinc.com/2020/02/what-are-carbon-dioxide-fire-extinguishers-and-do-i-need-one/, https://www.thesilverlining.com/westbendcares/blog/tips-for-selecting-a-home-fire-extinguisher, https://blog.qrfs.com/180-a-guide-to-home-fire-extinguishers-types-and-placement/, https://www.lincolncounty.org/DocumentCenter/View/7740/How-to-Put-Out-a-Grease-Fire?
The information is outstanding