Which device generates a supervisory signal at the FACP?

The air pressure switch in a dry-type system generates a supervisory signal at the Fire Alarm Control Panel (FACP). These switches monitor the air pressure within the dry sprinkler system's pipes and are crucial for ensuring the system is adequately charged and ready for operation. When the air pressure falls below a predetermined threshold, the switch activates and sends a supervisory signal to the FACP, alerting the system operators to a potential issue that needs to be addressed, such as leaks or pressure loss.

This supervisory signal is essential for system maintenance and ensuring that the fire protection system remains functional. Proper air pressure is vital for the sprinkler system to operate effectively in the event of a fire, as it ensures that the system can deliver water appropriately when activated. Thus, the air pressure switch serves a vital role in the overall safety and reliability of fire suppression systems in buildings.

The other choices, while they may have their specific functions related to fire safety and alarms, do not specifically generate supervisory signals at the FACP in the same manner as the air pressure switch.