The heat resulting from a fire makes the sprinklers bulbs exploding. All air maintained inside the piping system is evacuated. When the air pressure is under the clapper opening pressure, the clapper raises, allowing water to enter the system, including the alarm device. The water motor gong is operating.

Dry Pipe Valve is a latching differential valve used to separate the water supply from the dry pipe sprinkler system. The valve combines a positive latching clapper and air plate assembly, with a differential air to water seat design. The latching clapper and air plate assembly provides a positive mechanical seal for the air pressure in the dry pipe system.