Ultrasonic flow meter 340Ci signals are magnified in the direction of flow but delayed in the opposite direction as soon as the fluid in the tube begins to flow. The flow rate is proportional to the difference in transit times between the two sensors. An ultrasonic flow meter that requires particles or bubbles in the flow is an ultrasonic flow meter (non-intrusive Doppler flow meters). Ultrasonic meters are appropriate for wastewater applications or any conductive or water-based unclean liquid. Doppler flow meters are often ineffective when used with distilled or drinking water. Clean liquid applications would need aeration. Ultrasonic flow sensors are also suitable for applications requiring minimal pressure drop, chemical compatibility, and low maintenance.The flow volume of a wide range of gases and liquids may be measured reliably using ultrasonic waves — regardless of electrical conductivity, pressure, temperature, or viscosity. Inline ultrasonic sensors are ideal for usage in applications that demand traceable and assured accuracy. Clamp-on ultrasonic sensors, on the other hand, are mounted on the pipe’s outside wall, allowing for temporary measurements or retrofitting.