Abstract: An apparatus for extracting a gas, in particular hydrogen, from a fluid stream utilizing a plate membrane flattened with a wave spring on the low pressure side of the membrane and a turbulence generator on the high pressure side. Alternately, the membrane is folded and wrapped against a central conduit within the membrane fold. Extraction membranes have a substrate layer of Ta—W, V—Co, V—Pd, V—Au, V—Cu, V—Al, Nb—Ag, Nb—Au, Nb—Pt, Nb—Pd, V—Ni—Co, V—Ni—Pd, V—Nb—Pt or V—Pd—Au alloy or combination thereof and a first layer affixed to the outer surface of the substrate towards a mixed gas flow which is composed of palladium, platinum, rhodium, and palladium alloys.