The Transit Time Flow Meter of the TTFM100 NEW GENERATION (NG) series measures flow rate by calculating the spread time of an ultrasonic wave in a liquid, going upstream and downstream into a pipe. This flow meter is mostly used to measure the flow rate of homogeneous fluids, also with a quite high percentage of suspended solids. The measuring system is composed of a couple of ultrasonic transducers acoustically coupled to the external pipes wall (it is also possible to use transducers in direct contact with fluid to be measured called wetted sensors) and a HOST unit elaborating the signals that are sent and received from the transducers. The HOST unit has a DSP microprocessor and gives signals for interfacing with the process or the control systems.