Measuring appts. detecting gases by electrochemical sensor - has variable diffusion block with variable aperture for different ranges during operation without ingress

摘要

The electrochemical sensor has an electrolyte chamber and measurement electrodes separated from its surroundings by a diffusion membrane. A diffusion block in-front of the membrane has a diffusion aperture (7) which is variable at least in its transmissivity. - The diffusion aperture can be closed by an associated valve arrangement (8) connected via a valve drive (9) to a measurement value comparator (11) for varying the working position of each valve to be actuated.