© 2016 Elsevier B.V. All rights reserved.García Gallegos, JaimeÁvila, SusanaBenyon Puig, RobertMcKeogh, G.Stokes, Andrew2025-12-182025-12-182016-03-03Journal of Natural Gas Science and Engineering 31: 293-3041875-5100https://www.sciencedirect.com/science/article/abs/pii/S1875510016301111https://hdl.handle.net/20.500.12666/1605Highlights Continuation of comparison performed in laboratory conditions, showing the good performance of the absorption spectroscopy. Behavior of this technique is checked together with the Al2O3 capacitive sensor but in underground gas storage facility. New sampling system was designed to adapt all instrumentation requirements and ensure an optimum metrological analysis. Performance of sensors is reported for all production stages and compared with those obtained under laboratory conditions. Study ranges covered: water vapor fraction (4; 350) ppmv, line pressure (3.4; 7) MPa and ambient temperature (−15; 40) °C.The work reported is the continuation of the extensive comparison performed in controlled laboratory conditions using natural gas from the Spanish grid, as part of the European Metrology Research Project (EMRP) “Characterisation of Energy Gases” (ENG01-Gas, 2009). One of the outcomes of the project was the good performance of a laser absorption spectrometer with respect to other measurement technologies, in particular the absence of appreciable drift effects, exhibited by aluminium oxide (Al2O3) sensors that are traditionally used in the natural gas industry. The investigation was performed over a wide range of humidity content (13 ppmv to 250 ppmv) in ambient conditions of 23 °C ± 3 °C, at Enagás central laboratory in Zaragoza, Spain (Gallegos et al., 2015). We report the subsequent comparison of two laser absorption analyzers, from different manufacturers, and a conventional Al2O3 installed on site in real industrial conditions, at an underground gas storage (UGS) and drying plant of Enagás in Serrablo, Spain. The performance of sensors is reported and discussed for all production stages of the plant (extraction, injection and shutdown), during which extreme ambient temperature values took place (from −15 °C up to 40 °C) and at line pressures up to 6.7 MPa. A purpose built sampling system was designed and constructed to accommodate the different instrumentation requirements and ensure an optimum metrological analysis. The new results are compared with those previously obtained under more ideal laboratory conditions in the context assuring compliance with the contractual specifications that are to be met in Europe (EASEE-gas, 2005).engHumidity analyzersNatural gasinfo:eu-repo/semantics/article10.1016/j.jngse.2016.03.005info:eu-repo/semantics/restrictedAccess