Which type of sprinkler head does not have a cap or release mechanism?

The deluge sprinkler head is designed without a cap or release mechanism, which enables it to operate under specific conditions where rapid water discharge is necessary. Deluge systems are used in high-hazard areas where a large volume of water is needed quickly to control fires. When the fire detection system activates, it opens the deluge valves, and water flows to all the sprinkler heads simultaneously. This design is crucial for managing fast-spreading fires and protecting properties that may require an immediate and overwhelming water response, as opposed to the selective activation found in wet and dry systems.

In contrast, wet and dry sprinkler heads have mechanisms that control the release of water based on fire detection. Wet heads contain water at all times, while dry heads maintain air pressure until the heat from a fire breaks the glass bulb or fusible link, allowing water to flow. Pre-action systems involve a two-step process where the detection system must first activate before water is allowed into the system, adding another layer of control. The absence of a release mechanism in deluge heads makes them distinctly suited for their intended applications, setting them apart from the other types.