Mount the Micronics UF DS200 ultrasonic sensor on the outside of metal or plastic pipes. The sensor continuously injects high frequency sound through the pipe wall and into the moving fluid where acoustic pulses are reflected back to the sensor from particles or bubbles in the fluid. Flow rates of most liquids can be accurately controlled including acids, caustics, lubrication fluids, chemicals, abrasives, waste water and sludge. There are no moving parts and no sensor maintenance is required. The compact, water tight electronics enclosure includes adjustable controls with separate ON and OFF relay set-points and time delay. A LED bar graph for flow rate and set points plus relay status are included. Installation can be made while the flow system is in full operation. No contact is made with the moving fluid and no holes are drilled in the pipe. There is no fouling or scale build-up on the sensor.