Abstract: In an evaluation method for a particle counter, a detector generates a signal in response to the presence of particles in a measuring area in which a liquid flow is conveyed. The sensor signal is treated by a signal processing device and is converted into a display value, taking into account at least one calibration factor. The sensor signal is treated in such a way that the individual residence times of the particles in the measuring zone are determined within a given lapse of time and a summated signal is formed by summating the residence times. The signal is used to represent the display value, taking into account the at least one calibration factor. A device for carrying out this includes a signal processing unit with a comparator circuit, a clock-pulse generator and a summation device in the form of a pulse counter, for example, in order to form the summated signal.

Abstract: A particle counter operates by the opacity method and has a light barrier or electric eye. The light beam of the light barrier or electric eye penetrates a measuring channel for a fluid transverse to the passage of the fluid through the channel. An electronic analysis assembly is connected in series following the receiver of the light barrier or electric eye. The light emitting surface of the light barrier or electric eye is formed by the end surface of a light-emitting fiber. The light inlet or receiving surface is formed by the end surface of a receiving fiber. The end surface of light-emitting fiber lies in a first boundary surface of the measuring channel. The end surface of the receiving fiber is concentric to the light-emitting fiber end surface and is located in a second boundary surface of the measuring channel parallel to the first boundary surface.