GB876202A - Improvements in or relating to rotary valves - Google Patents

Abstract

876,202. Washing granular materials. COAL INDUSTRY (PATENTS) Ltd. Jan. 12, 1959 [Feb. 25, 1958], No. 6077/58. Class 82(2) [Also in Group XXIX] A rotary valve for controlling the supply and exhaust of air to and from a washerbox for coal, comprises a rotor 1, Fig. 2, communicating at its open ends through passages 4 with a port 5 connected to the washer-box and having a port 2 on its cylindrical surface co-operable successively on anti-clockwise rotation of the rotor with first and second inlet ports 10, 11, Fig. 1, connected with a common inlet passage 6 leading to a compressed air source and first and second outlet ports 23, 22 connected with a common exhaust passage leading through a gap 9 to the atmosphere. In order to adjust the admission and exhaust phases in the cyclic operation of the valve in a manner comparable with the adjustment of the arcuate angles of the usual single inlet and outlet ports, the second inlet port and the first exhaust port are fitted with independently operable throttles 12, 24 respectively, co-operable with graduated scales fitted on the outside of the casing 3 to indicate the positions of the throttles. To prevent direct communication between the passages 6 and 7, the arcs subtended by the blind areas 3a, 3b of the casing are at least equal to and preferably slightly greater than the arc subtended by the port 2. To adjust the length of the blind area 3a, plates 26a secured to the casing by a plurality of bolts 27 are provided. A slide 8 adjustable by means of a clamp bolt 8a may be fitted to control the exhaust of air through the gap 9. It is preferable that the length of slide is such that it never completely closes the gap.