________ are similar to dry pipe sprinkler systems as they use closed sprinkler heads that release water through activation by a fire detector.

Preaction systems are designed to combine elements of both wet and dry pipe systems, making them unique in their operation. In a preaction system, the sprinkler heads remain closed until a fire detection device, such as a smoke detector or heat detector, senses an increase in heat or smoke. Upon activation of the detection system, a valve opens, allowing water to flow into the piping network, which is usually filled with air or nitrogen.

This approach provides a higher level of protection and control because water is only released when there is a confirmed fire, thereby reducing the risk of water damage that can occur with systems like wet pipe systems, which constantly contain water. The presence of a fire detection mechanism adds a layer of safety, ensuring that water is only discharged in the event of an actual fire.

In summary, preaction systems are similar to dry pipe systems because they utilize closed sprinkler heads and require an external activation event—a fire detection signal—before they release water. This makes them an effective choice in environments where the risk of accidental discharge needs to be minimized.