Abstract: An expandable carbonaceous paste comprising natural graphite flakes and expandable graphite flakes such as acid treated graphite flakes, mixed with a hydrocarbon viscous liquid such as tar so that when the paste is exposed to heat, the paste will expand and have good thermal conductivity characteristics and then upon further heating the paste will convert to a rigid carbon structure.

Abstract: Disclosed is an improved tool for washing the perforations in an oil or gas well bore casing. The tool includes a tubular mandrel having orifices, between pairs of pressure sealing packer cups, for discharging a cleaning fluid into the area between the tool and the casing. The longitudinal spacing between the packer cups is variable by means of variable length spacer sleeves placed between the packer cups. The mandrel having an axial internal by-pass tube for passing cleaning fluid and debris through the mandrel. The by-pass tube having a telescoping section for accommodating the elongation and contraction of the tube due to temperature changes. The by-pass tube also permits entering the tool into the casing by eliminating vacuum or pressure build-up in the casing.

Abstract: Servo control of a butterfly valve or the like, in which fluid flow is inherently non-linearly related to angular orientations of a vane or plug member, is effected through a function-generator mechanism interposed to render the system transfer function substantially constant. A function generator serving those purposes includes a mechanical cam-and-follower unit through which valve-controlling angular movements are maintained in a cosine-related slaving with angular movements of the rotor of an electrical servo motor.

Abstract: A ground fault detector-interrupter, including a differential transformer for detecting the difference between currents in the hot and neutral conductors connecting a load to an a.c. source, is provided with a resistor shunting the differential transformer primary winding in series with the hot conductor. By shunting part of the current in the hot primary around the differential transformer, the transformer is effectively desensitized under high in-rush current conditions to protect against false triggering that would normally be caused by non-uniformity in the transformer windings and/or less than precise placement of transformer leads.

Abstract: A ground fault detector-interrupter for a single phase three wire electrical system includes a polarity sensitive fault detector controlling a gate in a manner such that only the hot line that has a ground fault will be interrupted.