Abstract: A paddle type flow detector for an explosive environment is mountable onto a pipe. The detector includes a structure for mounting to a pipe, a substantially sealed switch housing containing an electrical switch, and a paddle located within the pipe. A lever mechanism connects to the paddle and extends up through the mounting structure and to the switch housing. A spring is contained between the switch housing and the mounting structure and is connected between the lever mechanism and a screw adjustable spring block. The spring is contained within a spring compartment formed between the switch conduit and the mounting structure. A slide rod is operatively connected to the lever mechanism and to the switch to change a state of the switch upon sliding movement of the slide rod. The slide rod is tightly fit within a bore of the switch housing and blocks a flame path between the switch housing and the spring compartment.

Abstract: A device for supervising movable articles or objects has a supervising member which can be attached thereto. The device includes a connector disposed in a housing. The housing includes an aperture and a rotary blocking member positionable between the connector and the aperture of the housing. The supervising member is coupled to the connector. The blocking member prevents the supervising member from being recoupled to the connector after it has been removed from the housing. An alarm system is also provided. The alarm system includes ambient condition detectors in communication with a control unit.