Hach Lange Gmbh

Klaus Bittner

Michael Kussmann

Manfred Battefeld

Andreas Golitz

Markus Hahn

Aurelia Stellmach-Hanulok

Feed devices for liquid samples serve to convey liquid samples, for example to convey a liquid sample from waste water in a waste water treatment plant so as to monitor the treatment process. Known feed devices feed continuously at relatively low speeds. Films may accrete in the feed line that hinder the feeding and may react with the liquid sample. Therefore, the feed line must be cleaned frequently. In view of this, it is the object of the invention to improve the handling and the maintenance of a feed device for liquid samples. According to the invention, this object is solved by the fact that the feed pump () feeds in a pulse-like manner and the feed pump () as well as the feed line () are configured such that the expansion volume of the feed line () during the feed pulse is at most 50% of the pulse volume. Thereby, the feed line is cleaned and kept free of accretions.

Feed device for liquid samples

Gas-selective electrodes in liquid analyzing devices have a characteristic curve K with a linear portion L and a non-linear portion NL. In the non-linear portion NL, the characteristic previously could only be estimated so that determinations of the concentration were rather inexact. According to the present application, the electrode is rinsed with an acid and the zero point voltage Uat the electrode is determined during the rinsing. Using the zero point voltage U, the non-linear portion NL of the characteristic K is determined with high precision so that even low concentrations c can be determined with great accuracy.

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Krefeld, Germany

Klaus Bittner