What is a water-flow switch and what condition does it signal?

• A. A device that detects water flow in sprinklers and signals a fire alarm condition when water movement is detected.
• B. A device that detects temperature.
• C. A device that opens valves.
• D. A device that measures humidity.

Answer: (A)

A water-flow switch is a sensor in a water-based fire suppression system that detects movement of water inside the pipes and signals the fire alarm when water is flowing. It typically uses a paddle, turbine, or a pressure-change mechanism that responds when water moves—for example, after a sprinkler head is activated. When flow is detected, the switch changes state and sends a signal to the Fire Alarm Control Panel to indicate a water-flow condition, triggering the alarm. This is specifically about water movement, not about detecting temperature, humidity, or opening valves.