What describes a dry sprinkler system that requires activation of a secondary device before the pipes fill with water?

A preaction sprinkler system is designed to enhance fire protection in environments where water damage is a concern, such as in museums or data centers. This system consists of a pressurized air-filled piping network that is not filled with water until two separate activation events occur. The first event is typically the activation of a smoke detector or a heat sensor, which indicates that a fire may be present. Only upon receiving this initial signal does the system trigger the secondary device, such as a deluge valve or other mechanism, which then allows water to fill the pipes.

This design helps to prevent accidental water discharge that could occur from a false alarm, effectively minimizing potential water damage in sensitive areas. The action of filling the pipes with water only after activation ensures that the system only responds when necessary, combining both fire protection and property conservation.

In contrast, a dry-pipe sprinkler system activates automatically when the system detects a significant drop in air pressure, indicating damage or activation of the internals. A deluge sprinkler system discharges water from all sprinklers simultaneously when activated by a fire alarm system or smoke detector. A standard sprinkler system typically uses a wet-pipe design, where water is constantly present in the pipes and activates immediately when a sprinkler head opens due to heat.