Flow Research released Module C of The World Market for Gas Flow Measurement, 2nd Edition, with a focus on custody transfer measurement of natural gas. The module compares different natural gas flow measurement technologies and projects market growth for each technology type through 2019.

According to Flow Research, much of the new technological development in ultrasonic and Coriolis flowmeters is aimed at developing technologies that excel at custody transfer. However, the flowmeter types that dominate the market for custody transfer of natural gas are differential pressure (DP), turbine and ultrasonic. Flow Research says this has a lot to do with history.

The American Gas Association (AGA) has studied custody transfer measurement and has issued a series of reports specifying how this measurement is to be done with different types of flowmeters. The earliest report by the AGA on custody transfer measurement came in 1930 when it issued AGA-1, a report on the use of DP flowmeters with orifice plates for custody transfer of gas. In 1981, the AGA issued AGA-7, a report that laid out standards for using turbine flowmeters for custody transfer applications. The report was entitled Measurement of Fuel Gas by Turbine Meters. In 2006, the AGA released a new version of AGA-7, called Measurement of Natural Gas by Turbine Meters.

The effect of these early approvals of differential pressure and turbine meters for custody transfer purposes resulted in a large installed base of DP and turbine meters used for custody transfer of natural gas. It was not until 1998 that the AGA issued AGA-9, a report detailing the use of ultrasonic flowmeters for custody transfer applications.

Flow Research says ultrasonic flowmeters do have a number of advantages over turbine and DP meters. They cause less pressure drop, require less maintenance, and do not have moving parts. While orifice meters also do not have moving parts, orifice plates are subject to wear, and need to be checked periodically to make sure they are still installed properly. Ultrasonic meters do require periodic recalibration, although there is no consensus on how often this needs to be done. Many companies choose to recalibrate their ultrasonic flowmeters as often as every three years or as infrequently as every seven years. There are also diagnostic methods that can be used to check whether an ultrasonic meter is reading correctly or needs recalibration.

Flow Research’s Module C study covers five flow measurement technologies: Coriolis, Ultrasonic, Differential Pressure (DP) flow transmitters, Primary Elements (used with DP flow transmitters), and Turbine.

For more information on Module C of The World Market for Gas Flow Measurement, 2nd Edition, visit www.gasflows.com.