Abstract: An arrangement of probes is described, which comprises a carrier formed as an intermediate flange, in which a plurality of radially extending mounting openings are provided. The inner surfaces of the carrier are provided with an electrically insulating corrosion resistant layer, which is preferably an enamel layer. The carrier is having a polygonal outline and plane mounting surfaces surrounding the mounting openings. Measuring probes provided with a mounting flange can be exchangeably and sealingly attached to the mounting surfaces. By arranging different probes a large number of different measurement functions and supervision functions can be achieved. As an example, carrier sleeves comprising a window can be built in, so that a visual observation or a turbidity measurement can be performed.