What device triggers a supervisory signal?

The device that triggers a supervisory signal is the valve supervisory switch. This component is designed to monitor the position of a control valve in a sprinkler system, particularly whether it is open or closed. If the valve changes from its normal state, the supervisory switch sends a signal to the fire alarm panel or monitoring system, indicating a change that requires attention.

For instance, if a valve that is supposed to be open is closed for any reason, this can indicate a potential issue in the sprinkler system's functionality, such as maintenance work or a malfunction. The supervisory signal serves as an alert that prompts further investigation to ensure that the sprinkler system remains operational and effective in providing fire protection.

In comparison, while a water flow sensor detects movement in the water within the system and a pressure gauge indicates the pressure levels, neither of these devices triggers a supervisory signal. Similarly, a heat detector is designed to sense elevated temperatures indicative of a potential fire but does not concern itself with the operational status of critical components like valves in the sprinkler system. Each of these other devices plays a distinct role in fire protection but does not perform the same supervisory function as the valve supervisory switch.