A movable valve 131 is movably supported by a support plate 135 within a valve body having a gas injection nozzle 129. The valve body consists of a plurality of members 103, 105, 107, 109, 127. Impermeable joints 147a, 147b, 147c are formed between the members. The support plate 135 includes a plurality of elastically deformable support portions each having an inner radial connection, an outer radial connection and a circumferential connection. The support portions are phase adjusted to radial fluid passages 131h formed in the movable valve 113.