The differences in the mist-forming principles of the two types of water mist nozzles inevitably lead to differences in their fire-extinguishing capabilities.
Impact water mist nozzles produce finer droplets, typically 0.2–0.4 mm in diameter. Because the droplets are dispersed by the splash plate, most of the water mist has a low initial velocity and significant air drift, resulting in a more pronounced cooling effect. Impact water mist nozzles are mostly used to protect hazardous areas containing flammable liquids, gases, and solids with a flash point below 66°C.
Centrifugal water mist nozzles produce larger droplets, generally around 0.2–0.3 mm, with a faster initial velocity. This results in stronger flame penetration than impact water mist nozzles. The discontinuous, intermittent droplets produced by centrifugal water mist nozzles also provide excellent high-voltage insulation.
Centrifugal water mist nozzles are characterized by their effectiveness against oil fires and their ability to extinguish electrical fires while the circuit is energized. After a fire is extinguished, the possibility of reignition is extremely low. Centrifugal water mist nozzles are commonly used to protect flammable liquids with a flash point above 66°C and electrical equipment. They are widely used for the protection of transformers, generator sets, inductors, oil-immersed switches, oil tanks, etc.
