What device initiates an alarm indicating a flow of water throughout a fire protection system?

The device that initiates an alarm indicating a flow of water throughout a fire protection system is the sprinkler water flow detector. This specific type of detector is designed to sense the movement of water in the sprinkler system, which occurs when a sprinkler head activates due to heat from a fire. When water flows through the piping, the sprinkler water flow detector triggers an alarm to notify occupants and emergency services, signaling that there is a potential fire situation that requires immediate attention.

This function is critical in fire safety systems, as timely alerts can facilitate a faster response to emerging fires, potentially saving lives and reducing property damage. The water flow detection is vital because it provides a clear indication that fire suppression is actively occurring, thus confirming a fire event has been detected and that additional responses may be necessary.