Carbon Dioxide Systems, NFPA 12; these systems are used in full flooding purposes in Areas that aren't habitable, as carbon dioxide is hazardous
Deluge sprinklers—sprinkler heads are normally open up and the pipes https://patch.com/north-carolina/raleigh/classifieds/gigs-services/467764/safeguarding-lives-and-property-all-american-fire-protections-quarter-century-of-excellence