The Coriolis and ultrasonic markets are the two fastest growing flowmeter markets. Both flowmeter types are in demand from end-users. Both are versatile and widely used in the process industries. Yet, how do they compare to each other in history, industries and applications?
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Ultrasonic flowmeters
Tokyo Keiki first introduced ultrasonic clamp-on flowmeters to commercial markets in Japan in 1963. In 1971, Badger Meter brought clamp-on ultrasonic flowmeters to the U.S. by reselling Tokyo Keiki’s meters. In 1972, Controlotron began manufacturing its clamp-on ultrasonic flowmeters on Long Island, N.Y. In the late 1970s and early 1980s, Doppler flowmeters began to be used. Because they weren't well understood, ultrasonic flowmeters were often misapplied. As a result, many users got a bad impression of them. In the 1990s, transit-time emerged as the leading ultrasonic technology, and ultrasonic meters began growing significantly in popularity and capabilities.
In the early 1980s, both Panametrics and Ultraflux experimented with ultrasonic meters for gas flow measurement. In the mid-1990s, a group called Group Europeen de Recherches Gaziers (GERG) published a technical monograph on using ultrasonic flowmeters for gas flow measurement. A monograph out of GERG led to increased European ultrasonic flowmeter use during 1996-99.
The GERG monograph laid the groundwork for the publication of AGA-9 by the American Gas Association. AGA-9 lays out criteria for using ultrasonic flowmeters for custody-transfer applications. Since its publication in June 1998, ultrasonic flowmeters have become widely used for custody transfer of natural gas. They're especially suited for measuring gas flow in large pipelines, easily handling flow in those above 20 inches in diameter, as well as smaller pipelines. Its main competitors for custody transfer of natural gas are differential-pressure (DP) orifice meters and turbine flowmeters.
The history of ultrasonic flowmeters since 2001 can be viewed from multiple perspectives. One way is to look at the product development that occurred during this time. There have been several advances in custody transfer meters, developing multipath meters, gas flow measurement, developing diagnostic capabilities, and calibrating ultrasonic meters.
Coriolis flowmeters
Coriolis flowmeters get their name from a French mathematician named Gaspard Gustave de Coriolis. In 1835, he wrote a paper describing how objects behave in a rotating frame of reference. Coriolis studied the transfer of energy in rotating systems like water wheels. When some people talk about how the Coriolis principle works, they give examples of the Coriolis effect. The Coriolis effect isn't the result of a force acting directly on an object, but rather the perceived motion of a body moving in a straight line over a rotating body or frame of reference.
It's not completely clear how we got from Gustave Coriolis’ analysis of the rotation of water wheels to Coriolis flowmeters. There seems to be some confusion between Coriolis force and Coriolis effect. Some people, who attempt to explain how Coriolis flowmeters work, appeal to the Coriolis effect as an analogy. Yet, there seems to be little relation between the Coriolis effect, which is acknowledged to be “fictitious,” and the operating principle of Coriolis flowmeters.
One possible explanation is that early inventors designed instruments that rotated the fluid, and so they called them Coriolis flowmeters. This makes a connection between rotational motion and the workings of Coriolis meters. Later, inventors abandoned the idea of rotating the fluid in favor of oscillating tubes. However, because their patents cited the earlier patents that appealed to fluid rotation, they kept the name “Coriolis” to describe their meters.
In August 1972, James E. Smith patented a “Balanced mass-moment balance beam with electrically conductive pivots.” In August 1978, James (Jim) Smith began patenting a series of devices that became the basis for the flowmeters produced by Micro Motion. The patent was filed in June 1975 and explicitly evoked the Coriolis force. Smith founded Micro Motion in his garage in 1977. In 1981, Micro Motion introduced its first single bent-tube Coriolis flowmeter, although the company introduced its first Coriolis meter designed for laboratory use in 1977. In 1983, Emerson brought out its first dual-tube Coriolis meter.
In 1984, Emerson changed the course of flowmeter history forever, when it acquired Micro Motion. It allowed the company to expand globally and continue to innovate. Emerson has never lost its grip on the Coriolis market that it obtained when it acquired Micro Motion.
Endress+Hauser introduced the first straight-tube Coriolis meter in 1987. This meter had dual tubes and later evolved into the ProMass. Up until 1994, nearly all Coriolis meters were bent-tube meters. While bent-tube Coriolis meters have advantages over many conventional meters, they do introduce pressure drop into the system.
Schlumberger was next to introduce a straight-tube flowmeter in 1993, but withdrew this product after several months. Krohne introduced the first commercially successful single straight-tube Coriolis meter in 1994. Since that time, this type has become increasingly popular with Coriolis users. Straight-tube meters address the problem of pressure drop because the fluid doesn't have to travel around a bend, making them better able to handle high-viscosity fluids.
Straight-tube meters can be drained more easily, which is important for sanitary applications. Liquids don't have to negotiate a bend or curve that residue can be left on. Straight-tube meters are popular in food processing and pharmaceutical applications.
Industries and applications
Both ultrasonic and Coriolis flowmeters are sold to the process industries. However, ultrasonic flowmeters are stronger in the oil and gas industry than Coriolis meters in terms of revenue. The oil and gas industry, including refining, accounts for more than 50% of ultrasonic flowmeter revenues, while oil and gas with refining makes up less than 40% of Coriolis sales worldwide, according to data from Flow Research’s "Volume X: the world market for flowmeters".
There are several reasons why ultrasonic meters do better in oil and gas than Coriolis meters. One is line sizes. Coriolis meters are expensive and unwieldy in line sizes above four inches. Even though Coriolis meters are manufactured in line sizes up to 16 inches, those above six inches in line size account for less than 10% of Coriolis revenues. Ultrasonic meters, by contrast, do especially well in line sizes 12 inches and up because it gives them more distance to send a signal across the pipe. Ultrasonic meters are widely used for custody transfer of natural gas, and many of these pipes have diameters above 12 inches. Ultrasonic meters excel in pipes with 20- to 42-inch diameters.
There are many types of pipelines used in oilfields. Gathering pipelines are typically under 18 inches, though some can be as small as 2-4 inches. Transmission pipelines are used to carry crude oil, natural gas and refined products long distances. They typically vary between 12-42 inches in diameter. Distribution pipelines carry natural gas to homes and businesses. Their diameters range from 2-24 inches.
While Coriolis meters are ruled out of many oil and gas applications, where they shine is in the sanitary industries that need flow measurement in smaller line sizes. Coriolis meters do extremely well in the chemical, food and beverage, and pharmaceutical industries. They far outpace ultrasonic flowmeters in these industries in terms of revenues. In percentage terms, they also exceed magnetic flowmeters in the chemical and pharmaceutical industries, and come close to magnetic flowmeters in food and beverage.
