Abstract
Velocity measurements in pneumatic conveying systems is becoming increasingly important for energy saving. Doppler techniques using lasers, microwave and ultrasonic sensors are discussed; the laser techniques appear most suitable for use as research and development aids in system design. Injected tracers are difficult to use, but can give an adequate measure of bulk velocity for system development purposes. Cross correlation of natural tracers in the flow uses robust sensors and shows promise of being a cheap method for on-line process control purposes.