A method for electronic embodiment of a valve arrangement for controlling a process in which a medium flow within a valve housing (2) can be moved axially arranged screw valve member (4) by control pressure at via an i / p - converter (14) is moved, with the i / p - converter (14) at least over a part of the switching stroke which ensures a constant opening cross section, in which a position sensor system (12) of the point in time at which different positions of the valve member (4) along the aeration or breathing apparatus - or venting stroke is determined, and from this by means of an evaluation unit (8) the at these positions, speeds prevailing of the valve member (4) are derived mathematically, the change in profile, a measure for the state of wear of the described represents.
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