The type of sprinkler system containing air and is actuated by a supplemental fire detection system installed in the same area as the sprinkler is a _________

• A. Wet pipe
• B. Dry pipe
• C. Deluge
• D. Pre-action system

Answer: (D)

This type of system is about a two-step, detection-activated protection. In a pre-action system, the piping is kept filled with air (or another inert gas) rather than water. Water is kept out by a valve and will only enter the pipes after a fire-detection system in the protected area is triggered. Once the valve is released by the detection signal, water fills the piping, and an actual sprinkler head must then be activated by heat to discharge water through that head. This setup minimizes accidental discharge and protects sensitive areas.

Other systems don’t fit because wet-pipe piping is always full of water, dry-pipe releases water into the pipes via a dry-valve but isn’t driven by an area-specific detection signal, and deluge fills all piping with water with open heads and releases through any heated head.