Abstract: The invention relates to a method for checking the operability of a cyclically controlled regeneration valve in a tank venting system of a motor vehicle which utilizes the realization that during operation of the system significant pressure variations are generated in a discharge line arranged between an adsorption filter and the regenerating valve whenever the duty ratio of the regeneration valve is within a certain range. If the regeneration valve is operated at such a duty ratio, the pressure variations in the discharge line are recorded and the extreme pressure valves are determined in an evaluation device for a specified time period after which the difference between the maximum and the minimum pressures is determined and if this difference is below a predetermined threshold, the regeneration valve is indicated as being defective.

Abstract: Process to obtain nitrogen from gas mixtures containing oxygen and nitrogen by using alternating pressure adsorption on carbon molecular sieves, which comprises an adsorption cycle and a desorption cycle, in which the desorption cycle--which may also include the pressure equalization step--includes an idle time, which amounts to between 20 and 80% of the total time of the desorption cycle, plus a correspondingly shortened desorption step, whereby the adsorber decompression line is completely opened at the beginning of the desorption step and is completely closed and kept tightly closed after the decompression to ambient pressure during the subsequent idle period.