Abstract: An electrochemical measuring device comprises an essentially planar sensor substrate with at least one electrochemical sensor, and a cover part in which a tunnel-shaped measuring channel is formed. At least one guiding groove is provided in parallel with the measuring channel. A sealing element which is positioned between the sensor substrate and the cover part to seal the measuring channel is provided with guiding bodies along its length, at least one of which guiding bodies projects into the guiding groove of the cover part. The sealing element is provided with narrow sealing lips bounding the measuring channel. Each short side of the sealing element has a guiding body projecting into recesses in the sensor substrate. The guiding bodies are disposed on that side of a sealing plane defined by the sealing lips, which faces away from the cover part.

Abstract: In order to avoid dead volumes in a valve for control of a branch line departing from the main line in a valve chamber located in a valve housing, the valve chamber contains an elastomer part provided with a main channel and a branch channel departing from it, and the two ends of the main channel are sealingly connected with the main lines. The free end of the branch channel is sealingly connected with the branch line, and further that a valve lifter be provided in the valve housing, which acts on the branch channel in the branch-off area directly adjacent to the main channel of the elastomer part, thus reducing the cross-section of the branch channel, which is held in place by a counterpiece in the valve housing.