Abstract: A switch actuator includes an operator plate which provides a structure for mounting the actuator and for supporting the remaining parts. An operator shaft receives torque from an operating handle and via mechanical coupling, transmits torque to a torque plate subassembly. The torque plate compresses a torsion spring which provides temporary energy storage for the switch actuator. The torsion spring acts on a reaction plate subassembly which mechanically couples the torque generated by the spring to a rotor tube to operate the switch contacts. A spring guide subassembly maintains the spring in a predefined region to prevent the spring from deforming into a non-energy storing position during operation. The operator shaft, torque plate, reaction plate, spring guide, and spring are nested substantially concentrically about a predefined mounting axis.

Abstract: A full double wall tank, primarily for underground fluid storage, which is simpler and more economical to construct than conventional full double wall tanks. An inner tank shell, preferably of steel, provides primary fluid containment and is the principal structural basis of the tank. An intermediate barrier layer is applied over the inner shell to define secondary containment space, and provides a base for application of a resin outer secondary containment tank shell which is preferably fiber-reinforced. Monitor sensor means is provided having access to the secondary containment space, preferably proximate the bottom of the tank. The barrier layer is preferably such as to provide a minimum of fluid-receiving secondary containment space for rapid and highly sensitive monitoring, and to provide cathodic protection for a steel inner tank shell.