Abstract: The safety device comprises a rotatable lock-operating rotor having a first key slot extending transversely thereof, a non-rotatable inner cylindrical body adapted for fixed securement to a door or the like, and a hollow cylinder embracing the rotor and the cylindrical body and having its inner end fixedly secured to the cylindrical body or member. Key-operable pins, plungers or pistons interconnect the rotor and the fixed cylindrical body to prevent rotation of the rotor. The rotor is formed with a first key slot extending transversely thereof and the hollow cylinder has a closed outer end formed with a second key slot extending transversely thereof. A rotatable diaphragm member is interposed between the fixed outer end of the hollow cylinder and the rotor, and has a third key slot extending transversely thereof. The rotor may be disconnected from the fixed cylindrical member by a key inserted into the first slot to engage the pins, plungers or pistons.