Abstract: A device is provided, designed to prevent unauthorized operation of fire hydrants by completely concealing the hydrant operating nut and weather shield within freely rotating sleeves, thereby rendering the hydrant inoperable. The hydrant is made operable by the use of a specially designed self-contained magnetic operating wrench. The hydrant again becomes inoperable when the magnetic wrench is disengaged. The device is externally mounted for easy, quick field installation with common tools, and requires no modification of the internal hydrant mechanism. The device is designed to be used on all hydrant makes and models having an operating nut extending vertically above the hydrant bonnet.

Abstract: The operating stem of a hydrant is protectively surrounded by a steel collar which upstands considerably above such stem so that only a special deep socket for a wrench can be used to engage and turn the stem. When the hydrant is without a weather guard the collar is fixedly welded directly to the bonnet and has side openings to permit solid objects and water to escape from within and not interfere with the turning of the stem. Where the hydrant has a weather guard, a flanged adapter is welded directly to the bonnet to cover the weather guard and the collar has a flanged lower end whereby it is held in place axially by the adapted but is free to rotate.