The linked reference indicates that: "An instrument commonly used to measure leaks in natural gas infrastructure has a critical sensor transition failure issue that results in underestimation of leaks, with implications for greenhouse gas emissions estimates as well as safety."
Touché Howard, Thomas W. Ferrara & Amy Townsend-Small (2015), "Sensor transition failure in the high flow sampler: Implications for methane emission inventories of natural gas infrastructure", Journal of the Air & Waste Management Association; DOI:10.1080/10962247.2015.1025925http://www.tandfonline.com/doi/abs/10.1080/10962247.2015.1025925
Abstract: "Quantification of leaks from natural gas (NG) infrastructure is a key step in reducing emissions of the greenhouse gas methane (CH4), particularly as NG becomes a larger component of domestic energy supply. The United States Environmental Protection Agency (USEPA) requires measurement and reporting of emissions of CH4 from NG transmission, storage, and processing facilities, and the high flow sampler (or high volume sampler) is one of the tools approved for this by the USEPA. The Bacharach Hi-Flow® Sampler (BHFS) is the only commercially available high flow instrument, and it is also used throughout the NG supply chain for directed inspection and maintenance, emission factor development, and greenhouse gas reduction programs. Here we document failure of the BHFS to transition from a catalytic oxidation sensor used to measure low NG (~5% or less) concentrations to a thermal conductivity sensor for higher concentrations (from ~5% to 100%), resulting in underestimation of NG emission rates. Our analysis includes both our own field testing as well as analysis of data from two other studies (Modrak et al., 2012; City of Ft Worth, 2011). Although this failure is not completely understood, and although we do not know if all BHFS models are similarly affected, sensor transition failure has been observed under one or more of these conditions: 1), calibration is more than ~2 weeks old; 2), firmware is out of date; or 3), the composition of the NG source is less than ~91% CH4. The extent to which this issue has affected recent emission studies is uncertain, but the analysis presented here suggests that the problem could be widespread. Furthermore, it is critical that this problem be resolved before the onset of regulations on CH4 emissions from the oil and gas industry, as the BHFS is a popular instrument for these measurements."
Extract: "A popular scientific instrument used to measure methane leaks from oil and gas operations severely underestimates emissions under certain conditions, a preliminary study found. The results could have major implications for federal policies as the Obama administration moves to regulate methane from the natural gas industry."