Which sprinkler system requires manual activation?

The dry/manual system is designed to require manual activation in firefighting scenarios. This system typically consists of piping that is filled with pressurized air instead of water. In the event of a fire, the activation involves the manual effort of a firefighter or an operator, who opens a valve to allow water to enter the system. The dry system is particularly useful in areas where freezing temperatures may pose a risk to conventional sprinkler systems, as it remains dry until activated.

In contrast, a wet/automatic system operates automatically, activating without manual intervention when heat is detected. Semi-portable and portable systems also have mechanisms in place that differ from the manual activation required in the dry/manual system.