| 摘要 |
959,845. Valves. H. E. B. SCOTT. Oct. 10, 1962 [Oct. 20, 1961], No. 37739/61. Heading F2V. A valve, for controlling the flow of a slurry such as that rejected from a screen in a papermaking process, comprises a valve chamber 10 for connection in a pipe-line and a valve member 14 or 114 in the chamber which is adjustable to provide, between one end of the valve member and a wall of the chamber, a variable area metering orifice, the valve member extending across the chamber in a direction inclined to the direction of flow to direct the solid constituents of the slurry toward the metering orifice, this orifice being of rectangular shape and having a width between one-third and two-thirds of the diameter of the pipe-line and having an area equal to that of the pipe-line when the valve is fully open. In Fig. 2 the pivoted vane closure member 14 co-operates with an edge 13. Flushing water is supplied through passages 18, 19, 20 in the valve member to wash the sliding faces of the vane. In the embodiment of Fig. 5, the rectilinear slide valve member 114 fits against longitudinal abutment surfaces of the chamber 10 on the downstream side, the member having a bevelled end 28 which coacts with an inclined face 29 of the chamber to force the member against the abutments in closed position. Normally, the valve is maintained not less than 10% open by stops (not shown) and may be opened periodically to full bore. The invention enables the degree of opening required for a given flow area to be increased and thereby avoids the trapping of fibrous material when the valve is only partially open. An automatic system for periodically opening the valve to full bore, comprises a timing motor 21, Fig. 4, which operates a switch 1A, 1B, Fig. 4, in the circuit of a solenoid-operated valve 24 controlling an air-operated cylinder 16 connected to the main valve 14, the solenoid circuit being supplied through a transformer 22 paralleled with the motor. The valve may also be operated manually through a switch S2. Exhaust air is restricted by a needle valve 25. A non- return valve 26 in the supply ensures the cylinder 16 remaining under pressure in the event of failure in the air supply.
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