Which type of system utilizes a pressure supervisory signal to indicate an off normal condition?

A dry pipe sprinkler system utilizes a pressure supervisory signal to indicate an off-normal condition, such as a drop in air pressure within the system. In this type of system, the pipes are filled with pressurized air instead of water. When the sprinkler head is activated, the air pressure drops, allowing water to flow into the pipes and ultimately spray out of the opened sprinkler head. The pressure supervisory signal is crucial for monitoring the system's integrity, ensuring it remains ready for operation. If there are changes in pressure that suggest a leak or other issues, the supervisory signal will alert personnel to these conditions, prompting investigation and maintenance to ensure the system functions correctly when needed.