<p>The sensor has two grids of electrode wires (3,12) fastened in a sensor body (1) across the flow channel. The wires of the first grid cross those of the second without touching. Each wire can be individually switched from outside the sensor body. Each sensor is connected at one end via an insulating bead (4) to a spring fastened in a hole in the sensor body. The other end of each wire extends into an insulating tube which ends in a cavern (7) in the sensor body. The cavern is filled with a sealant. The bead and tube are outside of the measured cross section of the flow tube.</p>
