Paddle-type water-flow alarms should be installed in what type of systems?

Paddle-type water-flow alarms are specifically designed for use in wet pipe systems. These alarms operate by detecting the flow of water through the pipe and are activated when a certain threshold of water movement is achieved. In a wet system, the pipes are filled with water at all times, and any flow indicates that the sprinkler heads have been activated, signaling a fire.

The functionality of paddle-type alarms relies on the continuous presence of water, which is characteristic of wet systems. When the sprinkler heads open, water flows through the system, causing the paddle within the alarm to move, thereby triggering the alarm. This immediate response is crucial for early warning in fire situations.

In contrast, dry systems, which use pressurized air or gas to hold back water until needed, do not maintain a constant flow of water and therefore would not be compatible with paddle-type alarms. Hybrid and alternate systems may have components of both wet and dry systems, but they do not provide the same reliability and immediate activation that paddle-type alarms require, making them unsuitable for those types of installations.