Q&A: Flow & Level Sensors

Rajender Thusu, Ph.D., has been involved in the manufacturing industry for over 25 years. During this time, he has assisted users in product selection and manufacturers in the implementation of strategic marketing plans. As an industry analyst with Frost & Sullivan, Dr. Thusu has authored reports on a wide range of topics, including fluid power, sensors, and industrial automation. His prime focus has been in the area of sensors and transmitters. Dr. Thusu has over 15 years of cumulative market research and consulting experience. He can be reached at [email protected] or 210 247-3870.

Q: How has flow sensor technology changed over the past five years?

A: Flow sensor technology is experiencing a shift from vortex, mass, and electromagnetic designs to newer technologies. Some traditional flow technologies are expected to experience negative growth rates, and manufacturers may decide to exit those markets and shift toward newer flow technologies, such as transit-time ultrasonic and Coriolis mass flowmeters, which are expected to experience higher growth rates. Ultrasonic sensor-based instruments have registered double-digit growth rates in recent years. Superior technical characteristics and increased penetration into a wider range of applications should continue to support these high rates of growth.

The flow sensor market can be characterized by increased competition among different technologies for the same applications. For example, Coriolis mass flowmeters are gaining at the expense of positive displacement and electromagnetic instruments. Ultrasonic flow sensors compete with electromagnetic, differential pressure, and positive displacement technologies. Each technology has its own advantages and disadvantages and the final choice is often dependent on the price of the instrument and traditional customer preferences. While increased competition promotes technological advancements, it has an adverse impact on pricing, which eventually negatively affects revenue growth.


Q: Where do you see flow sensor technology heading over the next five years? What should users be looking for?

A: Although vortex, mass, and electromagnetic flow sensors have been experiencing competitive pressure from newer technologies such as ultrasonic and Coriolis mass, demand for these instruments is anticipated to remain stable and the sector is projected to see some modest advance in revenue share in future years.

With advances in technology, more customers are moving towards intelligent instruments — devices, which, in addition to flowrate, are able to provide customers with interpretation of some other variables and may also consist of a built-in microprocessor that can report on how the instrument is performing. Intelligent multiphase flowmeters are becoming more widely used in the oil and gas and water industries, and are also being considered in the food industry. Some manufacturers have launched multivariable differential pressure and vortex flow sensors. Users are becoming more aware of the significant potential for cost savings that could compensate for the higher initial investment in more advanced instruments. This should have a positive effect on demand in future years.


Q: For what types of applications has flow sensor technology proven most useful? Do you see any new applications emerging?

A: While some end-user industries tend to offer little opportunity for new applications, others offer significant growth prospects. For instance, manufacturers of flowmeters are experiencing a fall in orders from the chemicals industry, which could be explained by a decline in production of new chemical facilities in the Western world. On the other hand, flowmeters are seeing more customers from power generation and food and beverage industries. This changing focus on applications is anticipated to provide the industry with renewed growth opportunities.


Q: What is the state of radar-level sensor technology? How has the technology improved? For what types of applications is this technology showing the most promise?

A: The conventional through-air radar, known as frequency modulated continuous wave (FMCW), is slowly making way for micropower impulse radar (MIR) technology. Unlike FMCW, MIR uses a wave-guide to guide very low power microwave pulses. MIR, also referred to as guided-wave radar (GWR), is becoming more and more affordable for liquid-level sensor applications. Currently, some manufacturers are offering dual-version radar level solutions — one version with a solid rods detector and the other with a flexible rod detector. Both versions offer excellent resolution, repeatability, and an extremely low response time of under two seconds.


Q: What performance characteristics and/or design specifications should users be looking for in flow and level sensor technology?

A: Accuracy, repeatability of output, and resolution are the most important characteristics of a sensor technology. For level applications specifically, MIR technology has shown very high levels of satisfaction on these three counts.


Q: How significant is the push to move from flow switch to flow sensor technology? Are there significant numbers of users moving to replace mechanical switches? Is anything holding users back?

A: It depends on the type of use and the price–performance ratio. However there is a guarded move towards flow sensors for obvious advantages.


Q: If you had to pick the most obvious drawback of modern-day flow and level sensor technology, what would it be? Do you see manufacturers improving the technology in this area going forward?

A: Flow and level technologies are undergoing significant shifts. The technology is moving towards eliminating resolution, linearity, and repeatability errors. Further, there is a push to achieve perfect accuracy in transmitting result outputs, while at the same time reducing response times to a millisecond. Above all, manufacturers are always looking to improve the price-performance ratios for desired applications.

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