Which type of automatic sprinkler system requires the activation of a secondary device such as a smoke detector or manual pull-station before water is released into the sprinkler piping?

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

Answer: (A)

The concept here is two-step water release. In this type of system, water isn’t allowed into the piping until a secondary device is triggered—such as a smoke detector or a manual pull-station. Once that detection event occurs, a valve is released and water fills the sprinkler pipes, and then the sprinklers themselves release water when they’re actuated by heat. This setup helps prevent accidental discharge in sensitive areas.

That’s why the description matches a preaction system: it specifically requires a detector or similar device to activate before any water enters the piping. In contrast, wet systems already have water in the pipes and release it as soon as a sprinkler head is heated; deluge systems have all heads connected to opening piping and discharge water through any head when the system is activated; and dry systems keep pipes empty of water (pressurized with air) and introduce water only after the system valve is opened by activation, not by a separate pre-release device.