Ultrasonic Flow Meters: Design and Working Explained

Liquid and gas metering systems offer great performance and ultrasonic flow meters are quite popular a choice. Ultrasonic flow meter can be explained as a unique transducer which is capable of determining stream flow levels of various liquids or gases in a pipe by using ultrasonic signals.
 

In this post, we will understand the design and working principle of ultrasonic flow meters.
 

Ultrasonic Flowmeter Design

 

Ultrasonic flowmeters utilize an ultrasonic pulse which starts at frequencies ranging from 20,000 Hz and 1000 MHz. The flow meter comprises of three major parts named signal source, receiver and converter. A signal emerging from the source passes through the stream and finally goes to the receiver. Thereafter it goes to the convertor where the result is analyzed. Numerous pairs of sensors are installed and they are placed against each other. More often they are placed diagonally from the axis of the pipeline and they exchange signals. When you have such an arrangement in place, exchange of sound signals becomes easy in both directions of the flow- in the flow direction as well as against it. If the pipeline happens to be empty, both signals tend to cover the distance with equal speed. To put is simple, the higher the flow velocity, the higher the time difference between the signals.
 

Crude oil custody transfer metering systems are indispensable to the liquid and gas industry and ultrasonic flowmeters are a crucial part of it. Now, let’s take a look at various types of ultrasonic flow meters.
 

Types of Ultrasonic Flowmeters-

There are a number of ultrasonic flow meters which actually depends on the method of measurement. The measurement method can be Doppler, transit time and open channel.
 

Doppler:

Doppler measurement method enables the measurement of consumption in substances with huge proportion of impurities. The scattering of ultrasonic waves which come in contact with tiny particles in the flow stream are used to determine the speed.
 

A slight drawback of this method is lack of accuracy because the data is collected from a variety of particles.
 

Time transit:

The phase of the signal on the receiving piezoelectric elements is recorded. The receiver calculates the amplitude and speed ratio with which the ultrasound passes in the direction of the flow. The device later on serves the purpose of comparing results. You must note that a different schedule is run for the signals moving against the stream.
 

Open channel:

In this method the time of signal passage from the source to the receiver is analyzed along and against the flow. Pressure, density and temperature impact the duration of the signal movement. In this procedure, the time difference is proportional to the rate of flow.
 

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