Permanently piped systems of open or automatic water-spray type nozzles are intended for protection of flammable liquid hazards, conveyor openings, horizontal dryers and such. The automatic control equipment for open nozzle water-spray systems is the same as that used special sprinkler systems. The automatic opening valves are supervised as specified for deluge or preaction systems. The effectiveness of water-spray protection depends on many factors such as nozzle spacing, elevation, direction or angle of discharge, water pressure, wind velocity and the flashpoint, viscosity and temperature of the flammable liquid to be protected. Water-spray nozzles are intended to protect a hazard which cannot adequately be protected by conventional sprinkler systems. Each system is designed and calculated for the hazard, and each nozzle is chosen for its specific discharge characteristics (capacity, spray range, spray angle etc.). Applications include protection of spherical tanks, oil-filled electrical equipment, open flammable liquid storage and processing equipment, oil-cooled transformers, conveyor openings, and horizontal continuous dryers.