Patent ID: 8578798

Claim:
A probe system for measuring a measured variable of a fluid, especially a liquid, contained in a process container, comprising: a probe body, which is connectable to the process container by means of a process connection; an immersion tube axially shiftable in a guiding passageway of the probe body between a measuring position and at least two different treatment positions, said immersion tube, having a front end and a protective cylinder on said front end immersible in the fluid; a measuring probe held in the immersion tube, said measuring probe having a measuring head, wherein said measuring head is arranged within a region of said protective cylinder having openings; a first treatment chamber formed between said guiding passageway and said immersion tube; a second treatment chamber formed between said guiding passageway and said immersion tube, and adjoining said first treatment chamber on a side of said first treatment chamber facing away from said process connection; a seal arranged between said first and said second treatment chambers; and at least two fluid transport lines, which open into said first treatment chamber, of which one serves as a supply line and another as a drain line, as well as one other fluid transport line opening into said second treatment chamber and selectively serving as a supply line or as a drain line; wherein: said immersion tube has a first section with a first outer diameter and a second section adjoining said first section and having a second outer diameter smaller, than the first outer diameter, so that, by axial shifting of the immersion tube, the seal arranged between the first and the second treatment chambers can be opened.