1.A dry-pipe sprinkler system with open heads; is controlled by an automatic valve which is activated by smoke- or heat-sensitive devices; provides a dense, uniform coverage of water over the protected area.
2.A fire sprinkler system using open sprinklers (i.e., open sprinkler heads). When the fire detection system is activated, the deluge valve opens,
resulting in water being sprayed simultaneously from all of the open sprinklers; usually used for protection against rapidly spreading high-hazard fires.