Over the past decade, ultrasonic flowmeters have undergone a remarkable transformation. Once a niche technology, they are now among the fastest-growing flow measurement systems on the market.
Summarize this article with :
The first prototypes of this technology date back to the 1960s. Fuji Electric pioneered the development of ultrasonic flowmeters with the launch of its first FLH model in 1975.
Although they have been on the market for several decades, it's only recently that ultrasonic flowmeters have gained widespread acceptance.
There are several reasons for the growing popularity of ultrasonic flow meters. Advances in signal processing have led to improved noise filtering, resulting in greater accuracy and efficiency in flow measurement.
Improvements in signal processing technology have resulted in better noise reduction, increasing the accuracy of flow measurements. This improvement contributes to the growing popularity of ultrasonic flow meters and their widespread adoption in various industries.
Compared with mechanical flow meters, ultrasonic flow meters require minimal maintenance and are far more reliable. Suppliers, such as Fuji Electric, have also developed products tailored to specific industries and applications, including the ability to measure not only liquids, but also steam.
This focused product development has helped revolutionize flow measurement, making ultrasonic flowmeters an increasingly preferred choice in many industries and companies worldwide.
To fully understand the ultrasonic clamp-on flow meter, it's essential to start with the underlying principles of ultrasonic flow meters.
The term "ultrasonic" refers to the frequency of the sound waves used by these devices, which are above 20 kHz and therefore inaudible to the human ear.
Ultrasonic flow meters measure flow using these high-frequency sound waves, generated by transducers that use piezoelectric crystals to convert electrical signals into sound signals.
There are two main categories of ultrasonic flow meters: in-line flow meters and non-intrusive clamp-on flow meters.
The distinction lies in the way in which sound wave signals are transmitted, received and processed to measure throughput.
In-line flow meters feature transducers in direct contact with the process fluid, usually mounted on a prefabricated coil of standard length to ensure correct angle and ease of installation.
In-line meters have a longer history and tend to offer greater accuracy due to the absence of signal degradation caused by pipe walls, scaling and installation inconsistencies found in clamp-on meters.
As a result, in-line ultrasonic flow meters are often the preferred choice for transactional applications. Transactional transfer, also known as fiscal metering, involves flow metering applications in which ownership of the measured fluid is transferred from one party to another (billing).
Although these applications represent only a small proportion of all ultrasonic flow measurement scenarios, they play a vital role.
Unlike in-line meters, non-intrusive clamp-on meters are attached to the outside of the pipe, without coming into direct contact with the process fluid.ISO 24062:2023 formalizes their installation conditions and the expression of performance in closed pipelines.
These clamp-on ultrasonic flowmeters have undergone considerable technological advances, making them the fastest-growing of the two meter types. What's more, ultrasonic flowmeters offer exclusive advantages that contribute to their growing popularity.
Although all ultrasonic flowmeters use sound wave signals, they do not operate in the same way.
There are two main types of clamp-on ultrasonic flowmeters: transit time flowmeters and Doppler flowmeters, which differ in the way they transmit, receive and process sound wave signals.
Transit time flowmeters use a pair of transducers that act as both transmitters and receivers of sound wave signals. The speed of sound waves in a fluid is faster as they travel downstream, and slower as they travel upstream.
By measuring the time difference between these scenarios, the meter can calculate the fluid velocity and, subsequently, the volumetric flow rate. When combined with the known density of the fluid, the mass flow rate can also be determined.
Transit time ultrasonic flow meters are more versatile, capable of measuring both liquids and steam, but they generally only work with one type of fluid at a time. They require liquids containing a minimum of solid particles or entrained bubbles to avoid interference with the sound wave signal.
Doppler flow meters, on the other hand, measure the frequency shift of the sound signal, which is proportional to fluid velocity.
These flowmeters rely on the presence of solid particles or air bubbles in the flow stream to divert sound wave signals to the flowmeter.
As a result, Doppler meters are limited to liquids containing solid particles or air bubbles, such as dirty or aerated liquids and slurries.
Thermal energy meters, also known as BTU meters, measure the energy of hydronic heating and cooling systems using volumetric flow sensors, temperature sensors and a flow calculator.
With the growing importance of environmental regulations and financial incentives, thermal energy measurement is becoming increasingly essential for optimizing heating, ventilation and air-conditioning systems in urban energy systems and commercial installations.
Clamp-on ultrasonic thermal energy meters are ideal for retrofitting older systems, as they eliminate the need for costly and time-consuming piping modifications.
For ultrasonic transit time liquid meters to operate accurately, it is essential that the liquid contains a minimum of solid particles or entrained air bubbles. These can interfere with the sound wave signal and compromise measurement accuracy.
Until now, we've focused on fixed-mount clamp-on flow meters, which are installed in a single location, often with the electronic box mounted on a wall or pipe.
However, the clamp-on transducer design lends itself exceptionally well to portable flow measurement solutions. By combining clamp-on transducers with handheld electronics, it is possible to develop portable ultrasonic flowmeters.
These portable devices are usually equipped with portable electronics, transducers, fixtures and all necessary accessories in a compact carrying case.
Portable flowmeters offer unique applications that fixed-mount flowmeters cannot, such as spot checks, accuracy verification of other flowmeters and temporary replacement of fixed-mount flowmeters.
Spot testing involves taking temporary flow measurements in the absence of a fixed meter, often as part of system-wide flow studies. These studies help users to understand flows throughout the system, establish reference flows and identify leaks or blockages.
Portable meters can also be used to check the accuracy of another flow meter, particularly if it is showing unusual or erratic readings. This check helps to determine whether the problem is related to the process or to the meter itself.
In some cases, treatment plants require periodic calibration of their instrumentation, which may involve removing a flow meter for calibration at an accredited facility. During this period, a portable flowmeter can be used as a temporary substitute until the fixed meter is reinstalled.
Fuji Electric's portable flowmeter offers various signal output options, such as analog output, enabling seamless integration with control systems.
By using both fixed and portable non-intrusive ultrasonic flowmeters, operators can maximize process visibility while minimizing equipment costs.
A common strategy is to use fixed meters for critical measurements and portable meters for temporary measurements, to cover all potential blind spots.
In addition, Fuji Electric offers rental programs for portable ultrasonic flowmeters for temporary needs.
Many industry professionals use a combination of fixed and portable ultrasonic clamp-on flowmeters to optimize process control and maintain return on investment.
In recent times, advances in energy-saving visualization of electricity have accelerated the reduction of greenhouse gas emissions.
However, efforts to save energy by using steam have fallen behind schedule due to difficulties in visualizing steam losses.
To solve this problem, it was necessary to have a clamp-on ultrasonic flowmeter for steam that could identify steam losses without cutting the pipes.
While clamp-on flowmeters have been used for liquid measurements, it has been difficult to develop products for steam due to its extremely low ultrasonic transmission coefficient from pipes.
By employing noise reduction technologies, the use of Lamb waves, also known as ultrasonic waves, and advanced signal processing, Fuji Electric has successfully launched in 2019 the world's first flowmeter capable of measuring saturated steam at low pressure.
The Fuji Electric FSJ ultrasonic flowmeter for steam uses temperature or pressure sensors to measure thermal energy in saturated steam applications.
Thanks to their wide range of communication options, FSJ series flowmeters enable easy integration into building automation systems.
Although clamp-on ultrasonic flowmeter technology offers many advantages, it is essential to consider the application in question to determine its suitability.
Like all flow measurement technologies, ultrasonic clamp-on flowmeters have a unique set of advantages and disadvantages.
The adoption of clamp-on ultrasonic flow measurement is set to expand, as the benefits outweigh the limitations for a growing range of flow measurement applications. While this technology is currently widespread in certain industries, it is set to expand into others.
Clamp-on ultrasonic flowmeters offer many advantages to process operators looking to measure liquid and vapor flow in a wide variety of pipe sizes and materials.
Non-invasive installation eliminates the need for costly pipe modifications or regular maintenance, while providing accurate readings with no measurement drift over time.
In addition, portable clamp-on ultrasonic flowmeters offer unique applications that fixed-mount flowmeters cannot, such as on-site inspection and checking the accuracy of another flowmeter.
Thanks to their versatility and cost savings, it's easy to see why many industry professionals use both fixed-mount ultrasonic flowmeters and portable clamp-on ultrasonic flowmeters to optimize their processes.
When it comes tooptimizing process visibility and reducing costs, ultrasonic clamp-on flowmeters offer a unique set of advantages.
With non-intrusive installation requiring no pipe modifications or maintenance, these devices are highly versatile in applications such as district energy systems, industrial facilities, pharmaceutical manufacturing, water treatment plants, oil and gas operations, food processing, chemical production, HVAC systems and spot checks for flow studies.
Portable flowmeter models are likely to be the entry point for many users, given the lack of other commercially viable portable flow measurement options.
Ultimately, the selection of any process instrument, including flowmeters, depends on the specific requirements of the application and the determination of the most appropriate technology to meet these needs.
