Membrane valve (14a, 14b) having at least the following: a) an elastomer membrane (18a, 18) which is held by means of a radially outer edge-bead (34a, 34b) in or on a valve housing (21, 38a, 38b, 36a, 36b) and which co-operates with a membrane valve seat (28a, 28b); b) a first control chamber (26a, 26b) which is delimited by a first surface (46a, 46b) of the elastomer membrane (18a, 18b) that faces away from the membrane valve seat (28a, 28b) and which can be pressurised and depressurised by a pressure medium, such that when the said first control chamber (26a, 26b) is pressurised with pressure medium the elastomer membrane (18a, 18b) is pressed against the membrane valve seat (28a, 28b); c) a second control chamber (50a, 50b) which is delimited by a second surface of the elastomer membrane (18a, 18b) that faces away from the first surface (46a, 46b), which chamber surrounds the membrane valve seat (28a, 28b) and which can be pressurised and depressurised by a pressure medium, such that when the said second control chamber (26a, 26b) is pressurised with pressure medium the elastomer membrane (18a, 18b) tends to lift clear of the membrane valve seat (28a, 28b) and thereby the second control chamber (50a, 50b) is connected to a pressure medium flow channel (42a, 42b) at the end of which the membrane valve seat (28a, 28b) is formed, wherein d) the pressure medium flow channel (42a, 42b), the membrane valve seat (28a, 28b) and the elastomer membrane (18a, 18b) are arranged coaxially with one another in relation to an axial direction (52a, 52b), characterised in that e) an inside diameter (Di) of the pressure medium channel (42a, 42b) is 7.5 mm to 9.5 mm, and f) the Shore hardness of the elastomer membrane is at least 40 Shore A, and g) the smallest thickness (d) of the elastomer membrane (18a, 18b) in a central area (40a, 40b) of the elastomer membrane (18a, 18b), which central area as viewed in relation to a radial direction perpendicular to the axial direction (52a, 52b) is within the membrane valve seat (28a, 28b), is at least 30% of the inside diameter of the pressure medium channel. a) an elastomer membrane (18a, 18) which is held by means of a radially outer edge-bead (34a, 34b) in or on a valve housing (21, 38a, 38b, 36a, 36b) and which co-operates with a membrane valve seat (28a, 28b); b) a first control chamber (26a, 26b) which is delimited by a first surface (46a, 46b) of the elastomer membrane (18a, 18b) that faces away from the membrane valve seat (28a, 28b) and which can be pressurised and depressurised by a pressure medium, such that when the said first control chamber (26a, 26b) is pressurised with pressure medium the elastomer membrane (18a, 18b) is pressed against the membrane valve seat (28a, 28b); c) a second control chamber (50a, 50b) which is delimited by a second surface of the elastomer membrane (18a, 18b) that faces away from the first surface (46a, 46b), which chamber surrounds the membrane valve seat (28a, 28b) and which can be pressurised and depressurised by a pressure medium, such that when the said second control chamber (26a, 26b) is pressurised with pressure medium the elastomer membrane (18a, 18b) tends to lift clear of the membrane valve seat (28a, 28b) and thereby the second control chamber (50a, 50b) is connected to a pressure medium flow channel (42a, 42b) at the end of which the membrane valve seat (28a, 28b) is formed, wherein d) the pressure medium flow channel (42a, 42b), the membrane valve seat (28a, 28b) and the elastomer membrane (18a, 18b) are arranged coaxially with one another in relation to an axial direction (52a, 52b), characterised in that e) an inside diameter (Di) of the pressure medium channel (42a, 42b) is 7.5 mm to 9.5 mm, and f) the Shore hardness of the elastomer membrane is at least 40 Shore A, and g) the smallest thickness (d) of the elastomer membrane (18a, 18b) in a central area (40a, 40b) of the elastomer membrane (18a, 18b), which central area as viewed in relation to a radial direction perpendicular to the axial direction (52a, 52b) is within the membrane valve seat (28a, 28b), is at least 30% of the inside diameter of the pressure medium channel.