Type 8081 ultrasonic flow transmitter, from Bürkert Fluid Control Systems is a new transmitter for monitoring or controlling aqueous solutions. Applications include monitoring the cooling water during robot welding, injection moulding, die casting, as well as monitoring coolants in metal cutting applications. Thanks to the ultrasonic technology, it is also suitable for all applications where flow in a highly dynamic range (up to 1:500) needs to be measured with great accuracy (2% oR + 0.01% FS) using sensors with no moving parts. The measurement principle is based on the transit time technique: two piezo-electric sound converters transmit and receive the sound waves. The sound travel times are measured in the nanosecond range. The crucial point is that the ultrasonic signal moves faster in the flow direction than in the opposite direction: the difference in transit time is directly proportional to the flow speed and can therefore be used to determine the flow rate.