The American Gas Association published Report No. 9, Measurement of Gas by Multipath Ultrasonic Meters 2
nd Edition
[Ref 1] in April 2007. Report 9 details recommended practice for using multipath gas ultrasonic meters (USMs) in fiscal
(custody) measurement applications. This paper reviews some of the history behind the development of AGA Report No. 9
(often referred to as AGA 9), key Report contents, which includes information on meter performance requirements, design
features, testing procedures, and installation criteria. This paper also discusses changes that were incorporated in the latest
revision. Rev3 of AGA TMC Report 9 was published in July of 2017. A subsequent appended version was approved and
released in Oct of 2021.