inviolability device for the edges of the operation of the posts or openings of a fire and post of a fire, the mouth of a fire and trunk of the post of a fire thus teams

摘要

The knob stem (3) of the hydrant (5) can only be moved by a key with a body (9) which engages in the knob stem and which is joined to a handle by a rod. The knob stem has a base in non-magnetic material (7) such as bronze. The knob stem is attached in the usual way to the activating rod (11) and rotates by the application of its base on a bearing (13) attached to the hydrant. The bearing is also made of bronze. The base has an opening (24) in which a permanent magnet (27) is positioned so that it is raised in its housing when attracted by a the metal body (9) of the key. This does not happen when a tube of the correct size is inserted. The bearing also has a second opening (29) which is aligned with the first when they are in a specific position. When they are aligned the magnet slides into the second opening which locks the base with the knob stem allowing it to be rotated.