In the context of fire extinguishers, what is the primary function of dry chemicals?

The primary function of dry chemicals in fire extinguishers is to smother and prevent re-ignition of a fire. These chemicals work by interrupting the chemical reaction that is occurring in the fire, effectively eliminating fuel and preventing oxygen from reaching the flames. When dry chemical agents are discharged onto a fire, they form a coating that can smother the flames and will often work immediately to extinguish the fire.

This method is effective against multiple types of fires, particularly Class B (flammable liquids) and Class C (electrical) fires. The nature of dry chemical agents allows them to disrupt the fire triangle, hindering the fire's ability to sustain itself by cutting off the essential elements of heat, fuel, and oxygen.

Different fire-extinguishing agents have varying mechanisms; for instance, cooling agents lower the temperature of a fire, while agents that absorb heat would typically be more related to water-based extinguishers. However, dry chemicals specifically focus on smothering the flames to not only extinguish but also prevent any possible re-ignition once the source of ignition has been removed. This makes them particularly versatile and effective in firefighting scenarios.