|David W. Spitzer|
It is customary to end the year by summarizing how flow measurement has progressed and provide some prognostications for the state of flow measurement and control in the upcoming 12 months and beyond.
Size and Cost
The primary elements of flowmeter design are in a slow continuous process of miniaturization. Likewise, prices and margins are also shrinking. These size reductions give manufacturers the ability to reduce the manufacturing costs of the flowmeter.
For example, wafer-style flowmeters are becoming available in many technologies. This will make these technologies economically viable in certain applications. Other flowmeter characteristics consolidate multiple parts of traditional construction, such as a one-piece orifice plate with manifold and transmitter. These assemblies sometimes increase the purchase price of the flowmeter, but reduce its installed cost and the probability of installation errors. This trend will continue as companies and technologies compete for the same applications.
Flowmeter transmitters continue to shrink in size as new microprocessor-based designs replace older analog and digital designs. Because transmitters are already relatively small, further size reduction provides little direct benefit to the user. However, reliability generally increases as fewer and fewer components are used in the transmitter. Newer designs use better components that result in better long-term stability so the time between calibrations can be increased with corresponding economy. The performance of these transmitters is usually much better than previous equipment due to the use of higher quality components and improved signal processing techniques. Features that may have been difficult to implement in previous designs may be readily available. Conversely, some capabilities that are not in high demand such as multiple relay outputs have been discontinued. Flow computing functions continue to be integrated into the design of new transmitters. Multivariable transmitters now include differential pressure, vortex shedding, turbine, and ultrasonic technologies.
HART and Fieldbus
HART and fieldbus capability are being designed into new transmitters. Currently, technicians and engineers use HART primarily to communicate with the transmitter while it is installed in an analog loop. Both HART and fieldbus technologies can improve measurement performance by transmitting a digital output signal and eliminating the errors associated with the digital-to-analog conversion that is typically required to generate an analog output signal. This has not been readily adapted because the control system infrastructure used to read these measurements is generally not present. Communications will likely gravitate to TCP/IP. As such, flowmeters may eventually contain embedded Web servers that allow the flowmeter to be accessed via the Internet. This will decrease the customization necessary to design flowmeter interfaces.
The number of flow measurement companies continues to remain relatively large. There are approximately 22, 63, 70, and 53 suppliers of Coriolis, magnetic, ultrasonic, and vortex flowmeters respectively. Many of these 200-plus suppliers have multiple product offerings within their respective technologies. New companies continue to appear and some of these companies offer novel technology. However, most offer improvements of existing technology.
As labor and material costs increase in North America, Western Europe, and Japan, there has been a gradual move to manufacture flowmeters in other locations. Flowmeters have been made for years in relatively closed markets, such as Eastern Europe, India, and China. With improving standardization, communication, and transportation infrastructures, new designs of these flowmeters will become more available on the international market. This is occurring directly though the vendors and indirectly through private-label agreements. In addition, major North American, Western European, and Japanese companies have started manufacturing flowmeters in many of these locations.
Meanwhile, some things just never seem to change, as Flowmeters continue to suffer from poor selection and installation practices, especially when people with other training are asked to do more with less and take on the purchase and installation of a flowmeter or two. This activity can create many problems when the person has little prior experience or guidance.
Suppliers have attempted to reduce these problems by making their flowmeters more immune to poor installation practices. However, it is difficult to get around such fundamentals as not accumulating gas in a liquid pipe, or using a plastic flowmeter on a 500 C pipe. It is likely that this situation is not going to improve.
David W. Spitzer is a regular contributor to Flow Control with more than 35 years of experience in specifying, building, installing, startup, troubleshooting and teaching process control instrumentation. Mr. Spitzer has written over 10 books and 150 technical articles about instrumentation and process control, including the popular “Consumer Guide” series that compares flowmeters by supplier. Mr. Spitzer is a principal in Spitzer and Boyes LLC, offering engineering, expert witness, development, marketing, and distribution consulting for manufacturing and automation companies. He can be reached at 845 623-1830.