Sprinkler heads are always open on which system?

• A. Deluge
• B. Wet Pipe
• C. Dry Pipe
• D. Foam System

Answer: (A)

In a deluge system, every sprinkler head is open and unobstructed. The piping is connected to a water supply and remains pressurized, but no head is closed by a heat-activated valve. When the system is activated, water is discharged through all heads at once, providing immediate, full-coverage suppression across the protected area. This rapid blanket effect is why deluge systems are used in high-hazard spaces where fires can spread quickly. Other systems keep heads closed until heated (wet-pipe) or use air-filled piping with water entering the lines after a valve release (dry-pipe), while foam systems add foam concentrate for specific hazards.