Fire Suppression in Airports: Choosing the Right Agent

## Fire Classification and Suppression Every fire emergency is different and requires various firefighting tools and strategies to safely and successfully save lives and limit damage to property and the environment. Fires are categorized into five classes - A, B, C, D, and K, based on the type of fuel involved. Each class requires specific firefighting agents to effectively control and extinguish the flames. Firefighters learn about the five classes of fire and what firefighting agents are most effective at suppressing each one. Different classes of fire may require different firefighting chemicals to safely and effectively be extinguished. While fire classes are widely recognized, ICAO guidance focuses heavily on Class B flammable liquid fires, such as jet fuel, which represent the primary hazard in aviation incidents. ## Choosing the Right Firefighting Agent Airport firefighters are required to control and extinguish fires involving highly flammable jet fuel. Water is ineffective against Class B and C fires, which are common in airport emergencies. Using water could potentially make these types of fires worse because fuel will rise to the top of the water, enabling it to continue burning and spread as the water moves. Firefighting agents are required to suppress these types of fires, but water may still play a role. It is often mixed with the agents and used as a propellant to deploy the additional agents onto the fire. Firefighting foam was invented in the early 1990s and has evolved into various forms for different types of fires. Class B foam is designed for Class B fires and is used to coat the materials burning or at risk of burning, cutting off the oxygen supply. Internationally, firefighting foam used in ARFF operations must meet ICAO performance standards, which ensure that foam systems can rapidly control and extinguish high-risk jet fuel fires while preventing reignition. Dry chemicals, such as ABC, BC, and Purple K, are used to suppress all types of fires and are particularly effective on combination fires. They are primarily made from potassium and sodium bicarbonate and can be deployed using pressurized nitrogen or introduced to the water stream. Dry chemicals are frequently used in industrial or airfield settings, where chemical and electrical fires are most likely to occur. ## Clean Agents and Environmental Considerations Some firefighting agents used in ARFF fire suppression, such as certain types of foam, can contain substances which may have a negative impact on the environment. Dry chemicals can also spread easily over a large area, making cleanup costly and time-consuming. For this reason, clean agents can help mitigate potential environmental harm while still safely and effectively suppressing fires. Clean agents are gases and work by removing the oxygen from the air around the fire. They are useful for electrical and engine fires, and because they are gas, they won’t further damage the materials being extinguished. ## Training and Testing for ARFF Fire Suppression Knowing which firefighting agent to use and when to use it is a crucial part of training for all ARFF crews. In the United States, the FAA requires a specific curriculum for airport firefighters, which is repeated each year as part of a recertification process. Globally, ARFF training programs are often aligned with ICAO recommendations. The Oshkosh Airport Products ECO EFP system allows for the testing of a vehicle's foam system without discharging foam, reducing environmental impact and cleanup costs. The system has been approved by the FAA for testing and training purposes.