What triggers a pre-action fire system?

The correct choice is based on the operational principles of a pre-action fire suppression system. This type of system is designed to provide an additional layer of protection compared to traditional sprinkler systems. A pre-action system is triggered by the detection of a fire through both heat and smoke detection methods.

The combination of these two detection elements ensures that the system activates only when there is sufficient evidence of a fire, reducing the risk of accidental discharge that can occur with systems that respond solely to heat or smoke. When either heat detectors sense increased temperatures or smoke detectors identify smoke, this prompts the system to open a valve allowing water to flow into the pipes, thus preparing the system to discharge water in the event of a fire.

Overall, the inclusion of both heat and smoke detection in triggering a pre-action system provides a more reliable and safe method for fire suppression in settings where minimizing water damage is a priority.