D. Mari, S. Pasqualin, M. Zucco
Experimental determination of molar polarizability of nitrogen by a multi-reflection inteferometric technique

A novel optical pressure standard, based on a multi-reflection interferometric technique, has been recently developed. It is based on the measurement of the refractive index of a gas through an unbalanced homodyne interferometer (UINT) and is able to measure pressure with a relative standard uncertainty of 10 ppm at 100 kPa [1]. In this work, the interferometer was used to measure the molar polarizability of nitrogen, which resulted in agreement with recent previous determinations, paving the way for using photonic pressure standards as accurate and fast transfer standards of the pascal.

Tim Sparkes, Stefan Berdej, Christopher Roberts, Neculai Moisoi
Negative gauge pressure calibration methods using a PACE CM3 pressure controller

The development of pressure controllers has seen a great focus and their technical characteristics have improved over the last few decades, specifically in terms of their metrological capabilities. This advancement now makes them a suitable candidate to measure negative gauge pressure, either directly or in conjunction with other devices such as pressure balances. The Druck PACE in conjunction with CM3 (control module) has demonstrated performance characteristics in line with those required to complete negative gauge pressure calibrations. Three different calibration methods were developed within the Druck Ltd laboratory, from which two of them used a 200 kPa absolute pressure CM3, containing TERPS© (Trench Etched Resonant Pressure Sensor). The unit under test was a PACE1000 indicator built with a piezoresistive sensors with a pressure range from -100 to 100 kPa. The expanded uncertainty was evaluated for each method, as well as identifying the advantages and shortcomings of each method. As the calibrations were performed for gauge mode (not differential), the calibration range was -950 to -50 hPa.

Najji H. AlYami, Abdullah S. AlOwaysi, Khaled M. Ahmed
Traceable in-house preparation of RM CO2/N2 gas mixture using gravimetric standardized method

The necessity for national and international programs to monitor the levels of carbon dioxide emissions in the atmosphere has arisen as a result of the recent large greenhouse gas emissions that cause a rise in the Earth's temperature and climate changes with severe impacts. In order to give confidence in the monitoring results and enable the proper decisions to be made regarding the supply of environmental treatment and air quality through the limiting and monitoring of emission, it is required to maintain the traceability of the measurement data to SI units. Gas measurements laboratory at SASO-NMCC uses the gravimetric method to prepare reference gas mixtures of CO2 in N2 as primary standard mixtures (PSMs) cylinders based on universal gas law. The produced PSMs used as working standards to transfer the traceability from CRMs to customers’ artefacts. The used method fully complies with ISO 6142. Description of the steps of the production process and its method verification as well as equipment used and associated uncertainty are presented in this work. In accordance with the requirements of ISO 6143, a validated gas chromatography thermal conductivity detector (GC-TCD) method was selected to verify the mole fraction of the gravimetrically prepared gas mixtures. Reproducibility of the produced concentrations is demonstrated through mid-term and long-term evaluations. Eight certified reference materials (CRMs) of different concentrations were used for the GC calibration to provide metrological traceability of the measurement results to SI units. Associated uncertainty budget, with brief description of different components and error sources, is presented

Florbela A. Dias, Cristina Palma, Carlos J. Costa
Preparation of multicomponent mixtures to support carbon metrology

The Reference Gas Laboratory (LGR) of IPQ is participating in the project MetCCUS - Metrology for Carbon Capture Utilization and Storage under the new EPM (European Partnership on Metrology) Program. The goal of this project is to develop a metrological infrastructure that enables monitoring and detection of carbon dioxide leaks in energy and industrial processes, in transport networks and also allow the support of a better understanding of the life cycle of carbon dioxide. The contribution of LGR involves the preparation of certified reference materials (CRM) to allow the metrological traceability, providing support for the calibration and validation of instrumentation used in carbon capture processes.

Valnei Smarçaro da Cunha, Romeu José Daroda, Júlio Dutra Brionizio, Marcos Paulo Vicentim, Fernanda Figueiredo Nunes, Graziele Mozzer Pereira, Thais Fagundes da Silva
Assessment of moisture absorption by anhydrous ethanol under different environmental conditions

The main use of bioethanol in the world is as a fuel by adding it to gasoline. The addition of ethanol has many purposes, such as increasing gasoline octane number, reducing carbon dioxide emissions by fossil fuels, energy security and environmental sustainability. The suitable bioethanol for mixing in gasoline is the anhydrous one, which must contain up to a maximum of 1% (w/w) of water, according to ASTM D5798-21 [1]. Although it is well known that ethanol is a hygroscopic substance, a complete study addressing the rates of moisture absorption by the ethanol and its evaporation, or showing the influence of the environmental conditions on these factors cannot be found in literature. The assessment of these behaviours is fundamentally relevant for all the ethanol production and distribution chain in order to estimate how long an ethanol batch can be handled keeping the water content, or even to avoid significant loss of ethanol by evaporation, resulting in environmental problems and financial losses. In order to evaluate the ethanol behaviour under different environmental conditions, in this work, as a preliminary study, several environments with different relative humidities and temperatures were simulated in a climatic chamber, and their impact on the moisture absorption rate and/or on the ethanol evaporation were analysed in some anhydrous ethanol samples. It was also evaluated if moisture absorption or ethanol evaporation is the preferential process.