Which type of sprinkler is specifically designed to be visible when active?

The type of sprinkler specifically designed to be visible when active is the pendent sprinkler. Pendent sprinklers are installed on the underside of the sprinkler piping and are designed to be open and visibly active during a fire event. Their configuration allows water to be distributed in a downward direction, effectively covering a wide area beneath them.

These sprinklers typically have a distinct design that makes them noticeable, as they are meant to be seen when functioning, thereby signaling their operation to individuals in the vicinity. In contrast, concealed and recessed sprinklers are designed to blend into the ceiling or structure for aesthetic purposes; they are not intended to be visible when activated, as they often have covers that hide the sprinkler until it activates. Flush sprinklers, similarly, are designed to sit nearly flush with the ceiling plane to maintain a clean appearance, making them less visible when not in operation.