Which of the following systems requires that both a sprinkler and a detection system operate before discharging?

The preaction system is designed to address specific situations where extensive property protection is required before actual water discharge occurs. In this system, a fire detection device must first identify the presence of fire or smoke and subsequently activate the system, which fills the pipes with water. However, this is only the initial stage; for the water to actually discharge from the sprinklers, a secondary action is required, which is the activation of the sprinkler heads themselves. This two-step process – detection followed by the activation of the sprinkler – helps minimize water damage in the event of a false alarm or system malfunction.

In contrast, other types of systems, such as wet-pipe and dry-pipe systems, do not require this dual activation. A wet-pipe system allows water to flow immediately upon detection of heat or flame since the pipes are constantly filled with water. Similarly, a dry-pipe system, while it does delay water discharge until heat causes the valves to open (and thus releases air pressure), does not necessitate an initial detection system activation prior to releasing water. The deluge system operates differently as well; it discharges large amounts of water simultaneously once any detection device is triggered, without the need to wait for activation of individual sprinklers.

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