Nozzles/Water Spray

Nozzles and fixed water spray devices are the primary discharge components of fixed water spray systems, designed to apply water in controlled patterns to achieve extinguishment, fire control, or exposure protection. Unlike automatic sprinklers, these devices are typically open and operate simultaneously through deluge-type systems. Their function is to distribute water in specific droplet sizes, velocities, and spray geometries tailored to the hazard—ranging from surface cooling of equipment to flame knockdown and protection of adjacent exposures.

Common device types include full cone, hollow cone, and flat spray (fan) nozzles, as well as directional spray devices and high-velocity water spray (HVWS) nozzles. Selection depends on required discharge density, coverage area, and the thermal characteristics of the hazard, such as transformers, conveyors, or flammable liquid risks.

Design and application are primarily governed by National Fire Protection Association NFPA 15, which provides criteria for nozzle selection, system hydraulics, and installation. Additional guidance may come from FM Global Data Sheets (e.g., DS 4-1, DS 7-83) and international standards depending on jurisdiction.

These systems are uniquely suited for hazards where precise water application is required, enabling them to perform multiple roles—extinguishing active fire, controlling fire growth, or shielding critical equipment and structures from radiant heat exposure.