1,067,071. Pneumatic conveyers. GEBRUDER BUHLER. March 30, 1965 [April 1, 1964], No. 13404/65. Heading B8A. In apparatus for transferring bulk material between two zones at different pressures a sealed drum 10, Fig. 3, has at least two compartments 20 which are successively filled and emptied during relative rotation between the drum 10 and a feeder 6 and have inlet and outlet members 28, 29 carried by the drum 10 so that relative rotation between the drum and the closure members is avoided. In the example of Fig. 3 the drum 10 is rotatable below a fixed feed 6 of a separator collecting material from suction conveyer, a rotary seal 68 being provided for the feed support 7. Other examples, Figs. 7-11 (not shown), are described in which the sealed and compartmented drum 10 is stationary and the feed 6 is rotated to direct the material successively above the inlets of the compartments. In the example of Fig. 3, the inlet closure members 28 between an upper suction chamber 22 and the compartments 20 are opened successively under their own weight when cam-actuated valves 48 are opened to balance the pressure on opposite sides and are subsequently closed by atmospheric pressure on pistons 32 in arcuate cylinders 33 having cam-actuated inlet valves 40. Leakage apertures 38 are provided in the cylinders 33 so that on closure air enters the relevant compartment 20 to balance the pressures on opposite sides of the outlet closure 29 and release the material. The closures 29 are then successively closed by engagement of rollers 58 on cam tracks 57. In modifications (Fig. 6, not shown), the arcuate cylinders 33 are connected to a source of pressure air and in Fig. 11 (not shown), the lower closures 29 are also piston actuated. A system for removal of dust from the apparatus is described with reference to Fig. 12 (not shown), one of the valves (155) in an air lock device being piston actuated simultaneously with one of the inlet closures 28.
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