Dosing unit

摘要

A dosing unit is provided for adding a dosing agent to a mixing material. Such a dosing unit is intended, in particular, to be applied in adding water to concrete that is to be mixed. A control device (5) for driving a valve (4) is provided in common with a probe (6) for measuring the electrical resistance of the material to be mixed. The output signal of the probe is applied to the control device. Provided in parallel with the resistor (10) formed by the mixing material is a second resistor (9) which is substantially smaller than the smallest measured resistance of the mixing material. <IMAGE>