Which system requires both heat and smoke to trigger activation?

The pre-action fire system is designed as a combination of features to provide safety and proactive fire protection, which is why it requires both heat and smoke to trigger activation. This system integrates elements from both sprinkler systems and fire alarm systems.

In its typical operation, a pre-action system remains inactive until it detects smoke and/or an increase in temperature—both indicators of a potential fire. Once conditions are detected, the system fills the piping with water but does not release it until the sprinkler heads are activated, which occurs when the heat reaches a certain threshold or when smoke is detected in the area. This mechanism offers the advantage of reducing the risk of accidental discharge due to the dual-trigger requirement, making it suitable for environments where water damage needs to be minimized.

Other systems have different modes of operation: sprinkler systems activate based solely on heat at the sprinkler heads; fire alarm systems primarily signify danger through alarms and may not directly control water discharge; and standpipe systems are typically manual and rely on users to operate them during a fire event. Thus, the characteristic of requiring both heat and smoke distinctly characterizes the pre-action fire system.