Radar flow meters, by contrast, use microwave radar technology to determine the flow characteristics of a liquid or even a gas. These meters operate by emitting microwave pulses toward the fluid interface
The biggest difference between ultrasonic and electromagnetic flow meters is that ultrasonic flow meters do not require a conductive liquid to work. They also measure gases but fare less well with liquids that contain many solids or bubbles. Ultrasonic meters are able to withstand high temperatures and high pressure.