Ultrasonic flow meters measure liquid or gas flow through pipes using two types: transit time and Doppler. Transit time works best for clean liquids, while Doppler requires bubbles or particles. Both use two transducers to measure velocity, with Doppler using the frequency shift caused by particles. Ultrasonic flow meters are versatile and can measure various liquids and open channels.
Ultrasonic flow meters measure water or other liquids, and in some cases gases, flowing through pipes. These meters can measure both the velocity and the volumetric flow rate of a liquid. They are simple to use because unlike most types of meters, ultrasonic flowmeters clamp onto pipes rather than being installed into them, so the flow doesn’t have to be interrupted to install one.
There are two main types of ultrasonic flow meters: transit time flow meters and Doppler flow meters. Both types clamp to the outside of the pipes, but differ in the method used to measure flow, and each method has its advantages and disadvantages. Transit-time flowmeters work best for clean liquids, which don’t have many air bubbles or solid particles. Doppler flowmeters, in contrast, require the liquid to contain bubbles or particles in it to measure flow, but they also require the liquid to move at or beyond a certain speed.
Transit-time ultrasonic flowmeters, also called transmission flowmeters, use a principle called phase shift. Two transducers, which send and receive beams of ultrasonic energy, are placed some distance apart on the tube. The meter measures the time it takes for energy to travel in each direction and finds the difference between the two times. This difference is directly proportional to the velocity of the liquid, which is calculated by the flowmeter each time it takes a measurement.
Doppler ultrasonic flowmeters use the Doppler effect, which states that the frequency of sound waves depends on how both the sound source and observer move. Like transit time meters, Doppler manifolds use two transducers, but one transducer only sends and the other only receives. The sending transducer sends out beams of ultrasonic energy, and particles or bubbles in the liquid cause the frequency of the beams to change. This frequency shift is measured by the receiving transducer and is proportional to the velocity of the liquid.
Ultrasonic flowmeters are versatile, as they can measure the flow of various liquids, including not only water, but also wastewater, oils and liquids produced by industrial processes. These meters are most commonly used to measure flow in pipes, but can also be used to measure flow in open channels. This is done by measuring the water level in the channel, which can then be related to the volume flow.
Protect your devices with Threat Protection by NordVPN
