Deluge systems, a variation of automatic fire sprinkler systems, are specifically designed to combat rapidly growing fires. They achieve this by delivering large quantities of water in a relatively short period of time. Unlike regular closed sprinklers on wet-pipe sprinklers, these systems use open sprinklers, also known as open nozzles. A deluge valve controls the system water supply and is activated by a supplemental fire detection system or pilot sprinklers. Because open nozzles are installed, the suppression system piping is normally at atmospheric pressure. During a fire event, the detection system will trigger the deluge valve to open, releasing the water into the system through the open nozzles. This sudden surge of water makes deluge water spray effective in controlling fast-spreading fires.