If a fire extinguisher containing ammonium phosphate is used on a Class K fire, what is a potential negative effect?

Using a fire extinguisher containing ammonium phosphate on a Class K fire can create problems, particularly because it can counteract the foaming properties of any alkaline agents that may be applied. Class K fires typically involve cooking oils and fats, which require specific suppression techniques. The use of ammonium phosphate, which is an effective agent for Class A and B fires, is not suitable for Class K environments. If alkaline agents are introduced, the presence of ammonium phosphate can disrupt their foaming action, leading to reduced effectiveness in smothering the flames and ultimately putting responders at greater risk.

For Class K fires, it is essential to use agents specifically designed for this type of fire, such as potassium acetate, which forms a gel-like foam on the surface of the burning oil and helps prevent re-ignition. Therefore, understanding the specific characteristics and optimal agents for different classes of fire is crucial for effective fire suppression.