The turbidimeter is a handy device equipped with a large display, fulfilling all standards for a turbidity analysis on-site. The measuring range of 0 ... 1000 NTU is separated into two automatically switching measuring ranges for purposes of increasing the accuracy of the turbidimeter. With a well-arranged keyboard the turbidimeter is easy to operate. LED's are used as a light source, which work with a wave length of 830 nm in infrared ranges of light, and by that are invisible to the human eye. Since the measurement is not performed in a visible range, possible pigmentation of the sample plays a minor role during measurement. Due to a formation of the photodiodes in a 180 ° and 90 ° angle, transmitted light measurement is performed for higher ranges whereas diffused light measurement is used for lower ranges. With the reference standards of 0 NTU and 100 NTU included in the delivery, the turbidimeter can be calibrated or adjusted at any time. The turbidimeter PCE-TUM 20 fulfills according to EN 27027 / ISO 7027 all acquired standards.