Abstract: In order to achieve a high level of impermeability with a low closing force for the sealing elements of a multistage piston compressor, the overflow channel (19) in the valve piston (9) opens into at least two passages (26, 27) and the sealing plate of the overflow check valve (20) that is located in the valve piston (9) is configured as a freely guided closing membrane (28) with a limited stroke. The passages (26, 27) of the overflow channel (19) have different diameters, are arranged on a graduated circle at a radial distance from the axis of the closing membrane (28) and are completely covered by the closing membrane (28).

Abstract: The aim of the invention is to guarantee a high level of impermeability with a low closing force for the sealing elements. To achieve this, the overflow channel (19) in the valve piston (9) opens into at least two passages (26, 27) and the sealing plate of the overflow check valve (20) that is located in the valve piston (9) is configured as a freely guided closing membrane (28) with a limited stroke. The passages (26, 27) of the overflow channel (19) have different diameters, are arranged on a graduated circle at a radial distance from the axis of the closing membrane (28) and are completely covered by said closing membrane (28).

Abstract: The invention relates to a novel piston compressor whose return valves have a very good closure force and are extremely tight. The inlet return valve (15) is provided with a first sealing membrane (17) and the outlet return valve (30) is provided with a third sealing membrane. The two sealing membranes (17,32) are produced from an elastic polymer which has high disruptive strength, high temperature compatibility and memory properties.