What is a common feature of the preaction sprinkler system?

A preaction sprinkler system is characterized by its unique operation, which typically involves a piping network that is filled with air and only activates when specific conditions are met. The piping network must be airtight, meaning it is designed to prevent the infiltration of air and maintain the integrity of the system until a fire condition occurs.

When the detection system identifies a fire or heat event, it triggers the release of water into the piping. This is why the air tightness is critical; it ensures that the system remains pressurized and ready to respond effectively to a fire event without being compromised by unintended leakage or loss of pressure.

This contrasts with the other features. For example, preaction systems are not always active before a fire; they require the detection of heat or smoke to function. Additionally, while some systems may involve manual activation in certain scenarios, the primary operation relies on the automated triggering from the detection system. Moreover, preaction systems do not necessarily use less water compared to traditional systems; their design is focused more on providing protection in environments where water damage from sprinklers needs to be minimized.