Firefighting foam is a critical part of firefighting equipment. It’s used to extinguish fires and prevent them from spreading. Since the origin and nature of fire differ, six different types of firefighting foams exist.
Each variety of foam is intended for a particular application or situation. So, how would you decide on the appropriate type? That depends on what kind of fire you’re working with and how much time you have to put it out before it spreads beyond your control.
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Why Are There Different Types of Fire Fighting Foams?
The main reason for the proliferation of firefighting foam types is that fires differ. A two-alarm fire in a commercial kitchen requires a different solution than a forest fire, which needs to be extinguished quickly and efficiently.
The foam does not attack the flames directly. It effectively cools the fuel source, like the grease on the stovetop or dry grass. In this way, the foam acts as an effective retardant. It slows down any reactions that would lead to additional fuel being added to the fire. It also prevents re-ignition so that once your fire is out. It will stay off until you decide to put it back on again.
There’s another factor at play here, too. That is market competition. Firefighting foam is a big business, expected to hit 868 million USD by 2023. Companies have been pushing hard to improve their offerings to outperform their rivals. This competition has led them to develop new types of chemicals for use in their product formulas, also known as “chemical innovations.
Class A Foam
Class A foam is the most common type of foam used in firefighting. It is a mixture of water and a foaming agent that helps to soak up the liquid before it reaches the flame source. Class A foam is used to extinguish fires in enclosed spaces and can be applied manually or automatically.
Class A is so common because it’s highly effective. It has saved numerous lives throughout the years. In fact, from January 1 to 15, as high as 64 home fires occurred. If the fire department had done it right, they might have used this foam.
However, there are some downsides, too. You should never use Class A on flammable liquids. It won’t work well because if you try to put out an oil spill with water alone, nothing will happen until all moisture has evaporated. Hence, this type is ideal just for homes and other enclosed places.
Class B Foam (Protein and Synthetic Based Foam)
The two types of foam are protein and synthetic. Protein foams are made from animal proteins, while synthetic foams are made from petroleum products. Protein foams tend to be more expensive than synthetic ones. But they tend to perform better in cold temperatures. This makes protein foam ideal for colder climates like Canada or Alaska, where fires can easily break out during winter.
Protein foams have long been used by firefighters worldwide because they put off fires exceptionally well and do not harm people or animals unless consumed. However, their mere exposure is enough to cause cancer and other diseases. Protein foam contains heavy metals such as mercury which causes health problems, including kidney disease.
Recently, fire departments filed lawsuits against AFFF manufacturers due to their cancerous side effects. This firefighting foam cancer lawsuit has revealed that AFFF (aqueous film-forming foam) contains carcinogenic chemicals, PFAS, which are linked to different types of cancer and other medical problems.
They were unaware of the harm and kept using it until they started suffering. They blame the manufacturer for not warning them about this.
Alcohol Resistant Foam
If you’re fighting a fire involving alcohol, like a spilled bottle of wine or a car fire, it’s best to use an alcohol-resistant foam. This type of foam has better resistance than other foams and won’t clog the nozzle as easily. It also has a higher density than different types and expands more slowly, which can be helpful in situations where the fire is too hot for regular expansion rates.
Low-Expansion Foam
Low-expansion foam is the most common type of firefighting foam used today. Low-expansion foam is used for flammable liquid fires, which account for more than 90% of all reported fires in the United States.
The most recent case was in November when a 600-foot tanker ship docked in Alaska withstood two days of fire that had engulfed its hull and superstructure. The ship’s crew could extinguish the flames without suffering injuries or casualties. They probably used this foam to cool down areas near high heat sources, such as jet turbines and engines.
Low-expansion foams are also used for non-confined or open-air fires with no closed spaces to generate hazardous gases or fumes that can cause injury or death if inhaled into the lungs.
Medium-Expansion Foam
Medium-expansion foam is ideal for flammable liquids and gasses. Thousands of bourbon barrels were destroyed when two barrel rooms at a Jim Beam factory in Kentucky caught fire in 2019. The barrels were filled with alcohol, and the blaze was so intense that it created an inferno that burned for days, making it difficult to extinguish.
NIST researchers say they are still investigating what happened at the plant. Still, they believe medium-expansion foam would have been beneficial here because it contains water or other chemicals that expand into gas when heated by a fire.
Medium-expansion foams are also used to fight oil fires because the foam can form around oil droplets, keeping them from spreading and burning nearby areas such as homes or buildings.
High-Expansion Foam
High-expansion foam serves to put out flames in regions that are too large for regular foam. It can be used on vehicle fires, building fires, industrial fires, and aircraft fires alike. The high expansion properties of this type of foam allow it to thoroughly saturate even the largest of fires and put them out quickly.
Conclusion
There you have it: six different types of firefighting foams. Hopefully, this has been a fascinating look at some of the most commonly used foams firefighters use to fight fires. Take note that not all foams are the same. Each has distinctive features and applications that make it more appropriate for specific settings than others.
If you’re planning on using foam in your next firefighting training exercise or real-life situation, check with your local fire department beforehand. They can provide guidance on which type will work best for what situation.
