|David W. Spitzer, P.E.|
Where is the line between hype and reality? How should we determine what is new technology and what is simply a different incarnation of previous technology? These questions may seem philosophical, but their answers may hold the key to specifying, purchasing, and installing superior flow measurement systems. This is because different incarnations of previous technology usually contain advantages and disadvantages that have been previously identified and may have been quantified. Treating each improvement as a new technology can result in wasted time and inappropriate flowmeter selection.
Finding “new technology” is usually not a problem because practically every supplier will bring it to your doorstep. If you don’t believe this, just pick up a technical magazine and read the articles and advertisements. Few instrumentation suppliers are screaming about products they were selling 50 years ago. Yet, if a 50-year-old product was re-released with an exotic metal construction, you better believe suppliers would be jumping over backwards to tout the merit of this “new technology.” This is not to say the introduction of the product is not noteworthy. It is also not to say the product is not useful. It is merely saying the product is not new flowmeter technology.
In my mind, new flowmeter technology is just what it says — “new flowmeter technology.” The following table lists some examples of new flowmeter technology and when they were new (The list is not intended to be exhaustive.):
• 1920s — Orifice-Plate
• 1950s — Magnetic
• 1970s — Doppler Ultrasonic; Vortex-Shedding
• 1980s — Coriolis
• 1990s — Transit-Time Ultrasonic
• 2000s — Sonar Correlation
After introduction and market acceptance, improvements and refinements were made to each technology. For example, transmitters migrated from using pneumatic force-balance to analog components to microprocessor electronics. Similarly, signal transmission migrated from pneumatic pressure (3-15 psig) to current (4-20 mA) to digital communications (fieldbus). From a flow measurement perspective, these are not new flowmeter technologies — they represent improvements and refinements to existing flow measurement technologies.
For example, currently available differential pressure transmitters are different and vastly superior to those installed in the 1940s. However, the orifice-plate installed in the 1940s varies little from the orifice-plate of today.
Similarly, a gas flow measurement system of the 1940s might have been comprised of an orifice plate, differential pressure transmitter, pressure transmitter, temperature transmitter, multiplier/divider, and square-root extractor, while a current gas flow measurement system may contain a multivariable differential pressure transmitter (with flow computer) and temperature sensor that can perform the same (and more sophisticated) functions. In this sense, multivariable differential pressure transmitters are not a new flowmeter technology, but rather an improvement and refinement of orifice-plate technology that allows consolidation of functionality in fewer devices.
Now, these improvements and refinements can be quite important. Consider the difference in performance between AC and DC excitation of magnetic flowmeters. The performance of a magnetic flowmeter using AC excitation is expressed as a percentage of full scale, whereas the performance of a magnetic flowmeter using DC excitation is expressed as a percentage of rate. The use of DC excitation resolves a number of problems associated with AC excitation, but it is not a new flow measurement technology per se.
From a scientific perspective, what something does is more important than what anyone calls it. However, what we call something can shape the way people think about it. Shaping the way people think about something can cloud the line between hype and reality.
About the Author
David W. Spitzer, P.E., is a regular contributor to Flow Control. He has more than 25 years of experience in specifying, building, installing, start-up, and troubleshooting process control instrumentation. He has developed and taught seminars for almost 20 years and is a member of ISA and belongs to ASME MFC and ISO TC30 committees. Mr. Spitzer has published a number of books concerning the application and use of fluid handling technology, including the popular The Consumer Guide to… series, which compares flowmeters by supplier. Mr. Spitzer is currently a principal in Spitzer and Boyes LLC, offering engineering, product development, marketing, and distribution consulting for manufacturing and automation companies. He can be reached at 845 623-1830.
For More Information: www.spitzerandboyes.com