How Does an Ultrasonic Flow Meter Work?

Ultrasonic flow meters are flow meters that calculate the speed of a flow with ultrasound. They are volumetric flow meters which, for the most part, requires bubbles or particulates in the flow.

This flow measurement device is best for any dirty liquid or wastewater applications, which is conductive or water-based.

With that said, this type of measuring device won’t work with drinking or distilled water. For clean liquid applications, aerations are required. Moreover, ultrasonic flow meters are best for implementations where chemical compatibility, low-pressure drop, and low maintenance are needed.

There are three types of ultrasonic flow meters, transmission flow meters, Doppler flow meters, and open-channel flow meters. To know more about ultrasonic flow meters, do take a read!

Operation Principle

The fundamental rule of operation utilizes the Doppler Effect (frequency shift) of an ultrasonic sign when it’s sent back by gas bubbles or suspended particles (discontinuities) in movement. This metering procedure uses the physical phenomenon of a sound wave that changes recurrence when it is reflected by moving discontinuities in a streaming fluid.

Ultrasonic sound is transmitted into a pipe with streaming fluids, and the discontinuities mirror the ultrasonic wave with a marginally extraordinary recurrence that is straightforwardly corresponding to the rate of the stream of the fluid. Current innovation necessitates that the fluid includes, at any rate, 100 PPM (parts per million) of 100 larger or micron suspended particles or air pockets.

How It Works

Ultrasonic flow meters utilize sound waves to decide the speed of liquid streaming in a pipe. At no stream conditions, an ultrasonic wave’s frequencies sent into a pipe, and its appearance from the liquid is the equivalent. Under streaming conditions, the recurrence of the reflected wave is diverse because of the Doppler impact.

At the point when the liquid moves quicker, the recurrence move increments straightly — the transmitter procedures signals from the transmitted wave and its appearance to decide the stream rate.

Travel time ultrasonic flowmeters send and get ultrasonic waves between transducers in both the upstream and downstream headings in the pipe. At no stream conditions, it sets aside a similar effort to travel upstream and downstream between the transducers. Under streaming conditions, the wave (in the upstream direction) will travel slower and take additional time than the downstream wave.

At the point when the liquid moves quicker, the distinction between the upstream and downstream occasions increments. The transmitter forms upstream and downstream occasions to decide the stream rate. They speak to about 12% of all flowmeters sold.

Pros and Cons

The ultrasonic flow meters can be exact and is utilized for authority move (which means bookkeeping precisely for a costly liquid) of flammable gas and oil fluids. High turndown (can

peruse low as a level of the full scale or top perusing), handles high weights, is repeatable (steady), handles outrageous temperatures, can be utilized clasped to the outside of a pipe without entrance, is low support, exceedingly solid and self – diagnosing.

Weaknesses can incorporate staggering expense, affect the ability to stray procedure vibrations, issues with pipe measurement change because of development, and clasp on units have lower precision.

Ultrasonic flowmeters don’t hinder stream so they can be connected to sterile, destructive and rough fluids. Some ultrasonic flowmeters use cinch on transducers that can be mounted outside to the pipe and don’t have any wetted parts.

Brief stream estimations can be made utilizing convenient ultrasonic flowmeters with a brace on transducers. Brace on transducers is particularly helpful when channeling can’t be aggravated, for example, in power and atomic industry applications. What’s more, brace on transducers can be utilized to gauge stream without respect to materials of development, consumption, and scraped spot issues.

Nevertheless, alluring, the utilization of brace on transducers presents extra ultrasonic interfaces that can influence the unwavering quality and execution of these flowmeters. Specifically, if not appropriately connected and kept up, weakening of the ultrasonic sign can happen at the interfaces between the cinch on transducers and the outside pipe dividers, and between within pipe dividers and the liquid. Ultrasonic flowmeters are accessible in sizes to 72 inches and bigger.

How To Use

Ultrasonic flowmeters are generally implemented to gauge the speed of fluids that enable ultrasonic waves to pass, for example, water, liquid sulfur, cryogenic fluids, and synthetic concoctions.

Travel time structures are likewise accessible to gauge gas and vapor stream. Be cautious since liquids that don’t pass ultrasonic vitality, for example, numerous kinds of slurry, limit the infiltration of ultrasonic waves into the liquid.

In Doppler ultrasonic flowmeters, dark liquids can confine ultrasonic wave entrance too close to the pipe divider, which can debase precision as well as cause the flowmeter to neglect to

gauge. Travel time ultrasonic flowmeters can neglect to work when a murky liquid debilitates the ultrasonic wave to such a degree, that the wave does not achieve the recipient.


Above all these, be sure to know the whole process and implement these flow meters correctly. Because by then, you can get accurate results and you won’t have to worry about anything else.

Author’s Bio:

Sylvia Hopkins is a writer and a blogger who specializes in email marketing campaigns and ghost blogging. She writes about flow measurement instrumentation, flow measurement application, and technology. When not working, Sylvia spends some quality time with her family and friends.