AIR & WATER

MONITORING NEWSLETTER  

March 2013
No. 401

Ultrasonic Flow Meters Now More Popular in Oil and Gas

Many companies are changing from DP and turbine meters to ultrasonic meters because of their marked advantages. Jesse Yoder, of Flow Research, Inc., writing in Pipeline & Gas Journal, points out that ultrasonic meters are nonintrusive, cause virtually no pressure drop, do not have moving parts, are highly reliable and are very accurate. Leading suppliers of ultrasonic flowmeters for custody transfer of natural gas are Emerson Daniel, Elster and SICK. KROHNE has also entered this field. These meters are widely used for pipeline measurement of natural gas.

Like turbine meters, they can accommodate the large sizes of gas pipelines, but they can more easily handle particles and impurities in the flowstream than turbine meters. The market for custody transfer of natural gas has become the fastest growing niche in flowmeters, with the possible exception of the market for multiphase meters.

One issue that has remained unresolved is how often ultrasonic flowmeters need to be recalibrated. Some companies look for a period of years, such as five years or seven years, as a guide. So far none of the standards bodies, such as AGA, the American Petroleum Institute (API), or the International Organization for Standardization (ISO) have adopted such a standard. While the number of years would be a convenient guide, there are also diagnostic tests that can be run that may provide a better guide to the need for recalibration of an ultrasonic flowmeter than a standard that is stated in terms of a number of years.

Coriollis flowmeters are the most accurate type of flowmeter made. However, they have an easier time measuring liquid flows than gas flows.

In the past few years, several Coriolis suppliers have begun making Coriolis meters for line sizes above six inches. These include Endress+Hauser, Micro Motion and KROHNE. In the meantime, GE Sensing has acquired Rheonik and is continuing to make large-size Coriolis meters. Currently, the largest Coriolis meters are made for 16-inch lines.

Because of their accuracy and reliability, these large-line size meters may begin to penetrate the market for measuring petroleum liquids. Most of them are designed for custody transfer applications. Coriolis meters are already displacing positive displacement meters for liquid petroleum applications involving downstream delivery of petroleum to tankers, ships, trains, planes and trucks. It remains to be seen though, how widely they will be used for upstream oil applications in the oil fields.

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