MV-R Reverse Action Nozzles are open (non-automatic) spray nozzles designed for use in water spray fixed systems for fire protection of vessels or structures containing highly flammable liquids, gases and solids having flash- points of 66˚C (150˚F) and below. They are external deflector-type nozzles that discharge against the direction of the orifice in a uniformly filled spray pattern of medium velocity water droplets over a pre-determined area.