What operational feature distinguishes deluge valves in fire protection systems?

Deluge valves are a specific type of valve used in fire protection systems that can operate in two different modes: automatically or manually. This dual capability is a significant operational feature of deluge systems. In the automatic mode, the activation can occur as a response to heat or smoke detection, allowing for rapid deployment of water to extinguish fires. In the manual mode, personnel can directly control the activation when immediate action is required or when automated systems may not be suitable. This flexibility is crucial in fire protection as it enables systems to respond dynamically to various fire scenarios, making them effective in mitigating fire hazards.

The other options limit the operational capabilities of deluge valves, which does not accurately represent their function. Therefore, the correct understanding of deluge valves involves recognizing their ability to be activated in both automatic and manual ways, reflecting their design for responsiveness in fire protection.