Abstract: In one form of the invention, the control apparatus includes two stages: a poppet first stage and a piston second stage. The poppet first stage includes an altitude sensitive evacuated bellows coupled to a poppet valve. The second stage piston includes a pair of opposing head portions separated by a rod portion. The apparatus includes an output port which is coupled to a low pressure pneumatic signal or to a high pressure pneumatic signal, depending upon the position of the piston. For altitudes less than a predetermined altitude, e.g., 20,000 feet, the first stage develops a pneumatic servo signal which causes the piston to be in a first position which couples the output port of the apparatus to ambient air pressure. For altitudes greater than the predetermined altitude, the first stage develops a pneumatic servo signal which causes the piston to be in a second position which couples the output port of the apparatus to a high pressure pneumatic signal.

Abstract: A valve assembly for controlling the flow of a liquid fuel. The assembly includes a spring-biased movable valve member made of tungsten carbide, a captured sleeve member also made of tungsten carbide, and a readily accessible filtering screen member disposed in the fuel duct inlet of the assembly. In assembled form, the housing comprises two releasably connected constituent portions which integrate to form a one-piece unit. The structure of the unit, and the extreme hardness of the tungsten carbide material of which the valve member and the sleeve member are made, prevent corrosion and/or galling (such as by sand particles) and/or other normally-expected wear of the valve assembly, and thereby result in continued accuracy and reliability of the valve assembly, while maintaining simplicity and compactness of it.

Abstract: A temperature sensing assembly which continuously senses the temperature of a constituent stream, of a flow of a gaseous medium; and, as a result of such sensing, generates pneumatic servo-pressure to drive air valves, which control the flow of the constituent stream, to open and shut in accordance with specific requirements.