GB523799A - Improvements in valves - Google Patents

Abstract

523,799. Gate valves. DICKINSON, J. A. Jan. 14, 1939, No. 1312. Convention date, Jan. 14, 1938. [Class 135] In a gate valve of the type with two valve discs or closure members 6, 7, one of the discs 6 is opened before and closed after the other disc 7. The disc 6 is in this way less subject to erosion or " wire-drawing " as it opened under substantially " no-flow " conditions, and therefore remains effective to produce a tight closure whilst the other disc can be used merely to throttle the flow. Each disc has an inclined face to wedge against a corresponding seat 8, 9 and is provided with a lug or nut 10 internally threaded to receive the screwed operating spindle 3. The discs are recessed at 14 on their adjacent faces to receive the spindle 3 and in the case of the disc 6, to receive also the lug 10 on the disc 7. Lateral lugs on the discs are received in guide slots 13, one of which has a stop or ledge 17 to engage the disc 7. The lug 10 on the latter disc has an unthreaded part 16, Fig. 8, so that it is not engaged by the spindle 13 until a ledge 11 on the disc 6 engages this lug whereupon the discs rise together in spaced relation as shown in Fig. 3. In closing the valve, the discs descend together until the disc 7 engages the stop 17 and its lug is at the same time disengaged from the spindle. The disc 6 then completes its descent alone. The Specification, as open to inspection under Sect. 91, describes also modifications of the closure members in which the threaded nuts or lugs 10 are constructed as separate pieces. This subject-matter does not appear in the Specification as accepted.