Which type of sprinkler system requires the activation of a detection device before it discharges water?

The pre-action system is designed to require the activation of a detection device, such as a smoke or heat detector, prior to discharging water. This design serves as an added layer of protection, ensuring that the system only activates when there is a confirmed fire event or detection of smoke. The pre-action system typically consists of a dry pipe that holds water back until it is triggered by a detection signal, allowing for a controlled response to a fire while minimizing the risk of accidental water discharge.

When it comes to other systems, the wet pipe system has water ready and flowing in the pipes, automatically discharging when the sprinkler heads activate due to heat. The dry pipe system holds water under pressure but releases it immediately when the sprinkler head opens, again without needing prior detection. The deluge system operates similarly to the wet pipe but is designed to discharge water through all open sprinkler heads simultaneously when a detection device, usually a smoke detector, activates; however, this is less common than the pre-action system's function of confirming a fire event before water is released.

Thus, the pre-action system stands out for its unique feature of requiring an external detection signal before water is released, making it particularly useful in environments where accidental discharge could lead to significant damage.