Preparation of high-accuracy reference gas samples for proficiency testing

Abstract

Participation in proficiency testing is a mandatory requirement for laboratories that are accredited to ISO 17025, as the process of proficiency testing allows quality issues and biases that would lead to wrong measurement results to be identified and corrected. Since 2005 the Australian Government National Measurement Institute has delivered proficiency testing for various forms of natural gas that are produced in Australia, including pipeline natural gas from central and Western Australia, raw natural gas, coal seam gas, coal mine gas, LNG, and feed gas for LNG plants. The gas samples for proficiency testing are manufactured and verified by the National Measurement Institute according to international standards to have the highest levels of accuracy plus international comparability. Participants in natural gas proficiency testing include specialty gas companies, refineries, pipeline operators, gas producers, LNG plants, and independent gas testing laboratories. Many companies have a long history of participation that demonstrates continual improvement in the accuracy of their measurement results. This extended abstract gives an insight into the present state of the measurements of composition and calorific value of natural gas, and whether the measurements meet the international benchmarks for accuracy for LNG export. In addition, the extended abstract details the manufacture of the gas samples, and how proficiency testing studies operate, as well as examples where companies have improved their measurement performance across time.