Fire Extinguisher Yesterday and Today

The first recorded fire extinguisher was in London in the 18^th century. According to the encyclopedia these were constructed out of barrel-shaped vessels that were filled with a liquid solution.  Inside the liquid solution was a pewter chamber filled with gunpowder. In the event of a fire, a person would ignite the gunpowder, which would send a shower of the fire extinguisher liquid over the flames, helping to control the flame and eventually extinguish the fire.

In the early 1800s, the copper fire extinguisher was introduced. It contained Potassium Carbonate (salt), also known in those days as pearl ash. The copper cylinder was filled with this salt solution and then filled with compressed air. Other extinguishers were designed and patented in the early 1900’s. The most common of the day was the soda-acid extinguisher. These had 2 vials of sulfuric acid which could be broken and mixed with bicarbonate solution causing a reaction of carbon dioxide gas that would pressurize the water inside the cylinder. This combination would force the solution out of the hose once the handle was squeezed.

With the introduction of new chemicals, several different types of fire extinguishers were developed. The older labeling system used geometrical shapes with letter identification like the image on the right.

The most common classes of fire extinguisher are listed below:

CLASS A: SOLIDS like paper, wood, plastic Trash fires

CLASS B: FLAMMABLE LIQUIDS like Cooking Liquids, Gasoline, Oil, and Kerosene

CLASS C: Electrical (which will use a non-conductive agent)

CLASS D: METALS like Aluminum, Magnesium, and Titanium

CLASS K: Cooking Oils and Fats   

What does the above mean? First fire extinguishers are classified by fire type. The letter identifies which extinguisher can be used to extinguish that type of fire. For example, if your fire extinguisher has a marking on it like 2-A: 10-B: C  It has 2.50 gallons of water for a class A fire with a coverage distance of 10 square feet but meet the requirements for class B fire, and uses a non-conductive agent in case of a class C fire. In most locations today we find what is called the ABC fire extinguisher, like the one shown to the left, because of the many different types of fires it can extinguish.

If you work in a restaurant you would more than likely find a class “K” fire extinguisher which uses the ANSUL system seen to the right and is designed to be used on Vegetable oil and grease fires. It puts out the fire by cutting off the supply of gas. There are two ways that the ANSUL system will activate the chemical agent. The first method is to use the manual release button or cable which will stop the flow of gas and release the chemical agent through discharge nozzles. The second method is a fusible link that is mounted on top of the vent hoods. If the fusible link is exposed to certain temperatures the metal it’s made of will melt causing the chemical agent to be released through the discharge nozzles.

It’s important to be familiar with the type of fires you could be involved with so that you can choose the proper fire extinguisher. Also, make sure that you have had the proper training using a fire extinguisher. If you haven’t been trained, contact your local fire station to see when they offer classes.

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