The fire hose nozzle is the device that directs water or other media, such as firefighting foam, toward a specific target. The nozzle is attached to the end of the fire hose, and it must be compatible with both the hose and the intended media. In addition, the nozzle must be compatible with the type of fire that is being fought.
Fire nozzles are available in a variety of styles and materials, and there is no one-size-fits-all option. Fire nozzles can be made of stainless steel, brass, aluminum or polyethylene. They are typically connected to the hose by male couplings, which can be either a National Standard Thread (NST) or National Pipe Straight Hose (NPSH). The two types of threads cannot be used together; only NST male couplings can be connected to NPSH female threads, and vice versa.
When choosing a fire nozzle, firefighters must first decide what the nozzle will be used for. The most common nozzles are used for attacking the fire directly. These are often smaller in diameter, around 1.5 to 3 inches. They are also lighter, making it easier for firefighters to maneuver them. Larger hoses are used to transport water from a water source, such as hydrants, back-up hydrants or other water sources, to the fire scene.
Once the type of nozzle has been chosen, the next step is to select which size of fire hose is needed. This is determined based on the building where the fire is being fought and the nozzle’s recommended flow rate. For example, if the fire is being fought in a small apartment complex, a 1 3/4-inch handline may be required. This is based on the recommendation by Vestal and Bridge, which recommends a minimum initial fire flow of 160 gpm in 1 3/4-inch hose, assuming the use of a standard 15/16-inch smooth bore tip at 50 psi. This assumes that nozzle reaction is not being reduced due to line management or kinks.
The type of fire that is being fought also determines what type of media will be used. In general, Class A fires will be extinguished with water. This is because class A fires are caused by combustible material that is easily transported and spread by water. Class B fires are caused by combustible and flammable materials that can be more deeply dispersed by water than by class A fires. Class C fires are most commonly caused by electrical or corrosive materials and can be extinguished with water, foam or a combination of both.
Finally, class D fires are usually classified as the most difficult to extinguish. These are caused by combustible and non-combustible materials that cannot be easily transported and dispersed by water. These fires require more specialized extinguishing material, such as an aqueous film-forming foam (AFFF).