Which sprinkler system has air in piping, water flow control, fire detection devices, and closed sprinklers?

Which sprinkler system has air in piping, water flow control, fire detection devices, and closed sprinklers?

• A. Wet
• B. Dry pipe
• C. Preaction
• D. Deluge

Answer: (C)

Preaction systems keep the piping dry and require a two-step release before water reaches the sprinklers. The pipes are filled with air (not water) and are equipped with fire detection devices that must be activated first. When a detector signals a fire, a water-control valve admits water into the system, but the sprinklers themselves remain closed until the second step occurs (typically heat at a sprinkler head or an additional interlock), preventing accidental discharge. This combination—air in the pipes, a water-release valve controlled by detectors, and normally closed sprinklers—fits the preaction setup best. Wet pipe systems have water-filled piping and open sprinklers; dry pipe systems also use air in the pipes but do not rely on fire detectors to release water into all heads; deluge systems have water-filled piping with all sprinklers open.

Preaction systems keep the piping dry and require a two-step release before water reaches the sprinklers. The pipes are filled with air (not water) and are equipped with fire detection devices that must be activated first. When a detector signals a fire, a water-control valve admits water into the system, but the sprinklers themselves remain closed until the second step occurs (typically heat at a sprinkler head or an additional interlock), preventing accidental discharge. This combination—air in the pipes, a water-release valve controlled by detectors, and normally closed sprinklers—fits the preaction setup best. Wet pipe systems have water-filled piping and open sprinklers; dry pipe systems also use air in the pipes but do not rely on fire detectors to release water into all heads; deluge systems have water-filled piping with all sprinklers open.