Analysing the effectiveness of the DB Gold cylinder passivation treatment using ultra-low amount fraction gas stability studies

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In gas analysis, two important areas that affect measurement accuracy are reference materials and sampling. Both reference materials and samples are stored in high pressure vessels, normally aluminium. However, the aluminium surface structure can lead to reaction or adsorption of certain species in a gas mixture. In particular, reactive and "sticky" species will decay in an untreated cylinder. This can alter the amount of the component in the cylinder so when it comes to measuring the gas, the result will be different from what is expected. When measuring impurities in a sample, this may result in a false positive reading.Passivation is the process of treating or coating a surface to reduce the chemical reactivity. EffecTech has developed a passivation technique (DB Gold) which coats the internal surface of aluminium cylinders in order to reduce chemical reactions and surface adsorption. These cylinders could be used in a variety of gas analysis applications, including purity analysis of hydrogen for fuel cells vehicles and atmospheric monitoring of CO2\. However, the cylinders should be evaluated using representative mixtures and the stability of the mixtures over time needs to be measured. EffecTech does not have the capability to prepare these gas mixtures nor the analytical instrumentation to measure the composition.NPL are the national metrology institute for the UK. They have world leading facilities for the preparation of challenging gas mixtures and analysis using state of the art instrumentation. In this project we will collaborate with NPL by testing stability of a variety of challenging gas mixtures in the passivated cylinders. The results will allow EffecTech to grow the passivated cylinder sales and enter new markets. Additionally, NPL can use the data to make improvements to their own standards. End users of passivated cylinders, such as analytical laboratories, will benefit from more stable mixtures in the way of increased shelf life, greater measurement precision and lower uncertainties.This A4I project aligns well with government policy to be carbon neutral by 2050, facilitating the transition of the UK energy and transport sector towards decarbonisation and a hydrogen economy. Additionally, compared to other passivations, DB Gold does not require harmful chemicals during treatment and is therefore more sustainable and environmentally friendly.