GB883556A - Fluid operated valve - Google Patents

Abstract

A sampling valve for gas chromatography consists of a stack of plates comprising a flexible plate, a transfer plate having at least one hole therethrough, and a ported plate having at least two holes so situated as to be in communication with the hole in the transfer plate, the flexible plate, under the action of fluid pressure, being capable of deflection into the hole of the transfer plate to seal off the holes in the ported plate. As shown in exploded form two such valves are incorporated into one stack and the arrangement is suitable for re-routing gas streams in gas chromatography. One valve comprises a flexible plate 23, transfer plate 24 and ported plate 25 and is separated from the other valve, comprising ported plate 27, transfer plate 28 and flexible plate 29, by a labyrinth plate 26. Each valve is surmounted by a metal support plate 22, 30, an air manifold 21, 31 of Neoprene and an end plate 20, 32 of metal. The flexible, transfer and labyrinth plates are of Neoprene and the ported plates of metal. Alternatively, the transfer, ported, manifold and labyrinth plates may be of <PICT:0883556/III/1> metal, asbestos or synthetic resin, e.g. polytetrafluorethylene or polymethylmethacrylate, with gaskets between them. The plates may be bolted or clamped together. Control fluid, which may be liquid or gaseous, may be applied alternately to the upper flexible plate 23 through a hole 80 in the plate 20, an opening 81 in the plate 21 and holes 82, 83, 84 in the plate 22, or to the lower flexible plate 29 through holes 85 ... 95 in the plates 20 ... 30, an opening 96 in the plate 31, and holes 97, 98, 99 in the plate 30. When the lower flexible plate 29 is subject to pressure a flow of sample gas flows, as indicated by the dotted line, from a hole 33 through holes 34 ... 38 to a slot 39 in the plate 26 and thence through the hole 40, opening 41 and hole 42 to a slot 43 from which it flows by way of a hole 44, opening 45 and hole 46 to a slot 47 and thence through holes 48 ... 52 to an outlet 53. At the same time eluent gas passes from an inlet 54 through holes 55 ... 59 to a slot 60 and then through a hole 61, opening 62 and hole 63 to a slot 64 whence it flows through holes 65 ... 69 to an outlet 70. When the upper flexible plate is subject to pressure the holes 40, 42, 44, 46, 61, 63 in the plate 25 are closed and holes 71, 73, 74, 76, 77, 79 in the plate 27 are opened and the gas is re-routed whereby the eluent gas is caused to pass through the slot 43 so that a known volume of sample gas, i.e. that contained in the slot 43, is introduced into the eluent gas stream.