There are a multitude of different methods used to passivate the internal surface of aluminium cylinders by specialty gas manufacturers. However, as most of these technologies remain proprietary information not a great deal of details are known about these technologies. However, some details are known about existing methods which fit into one or more of the following categories:
Interestingly all aluminium surfaces, that have been in contact with air, are fairly well passivated by a quickly developing oxide layer. The most popular industrial passivation technology for aluminium is simply to increase the thickness of this oxide layer. The long pores in these increased thickness oxide layers are used widely in nanotechnology to build nano-fibres in them. Unfortunately, this technology cannot be used for passivating cylinders because of the very adsorptive structure of the developed layer. Aluminium oxide has an inherent, honeycomb like structure, even on a mirror polished surface. These are small cavities in the nanometre (nm) range. Most of the reactions that take place on the internal surface of an aluminium cylinder are not direct reactions with the aluminium (oxide) surface; they are cavity enhanced reactions catalysed by the aluminium oxide structure. Recently EffecTech has developed a completely new method of surface treatment that can inhibit this surface activity by “filling up” these small nano-structures. This new technology, known as the Performax® treatment, not only decreases surface adsorption dramatically, but seems to prevent even the most sensitive cavity enhanced reactions taking place. This lecture will present details of important surface structure and chemistry that takes place in aluminium cylinders and how different cylinder treatments attempt to overcome the problems such chemistry creates.
Dr Gavin Squire
Chief Executive, EffecTech Group of Companies
Qualifications BSc (Hons) in Chemistry with Mathematics
PhD in Chemistry
Professional Qualifications Fellow of the Royal Society of Chemistry (FRSC)
Chartered Chemist (CChem)
Memberships Principal UK Expert (ISO/TC158/WG4) – Gas Analysis – Comparison Methods
Member of ISO/TC158 – Gas Analysis
Member of ISO/TC193 – Natural Gas
Gavin has worked in the gas business for over 20 years covering a range of gas measurement disciplines from basic research to top level executive management with EffecTech. He is a gas metrologist with expert knowledge of the analysis of gases/natural gas composition and properties in both a laboratory and process environment.
His specific areas of expertise include
• Fundamentals of traceability and estimation of uncertainty in the measurement of gas content and properties.
• Development of analytical methods and uncertainty budgets for presentation to third parties as a basis for accreditation
• Liaison with national accreditation bodies and presentation of defendable validation data to fulfil the requirements of ISO17025 accreditation for calibration & testing laboratories
• Independent assessor of third party analytical laboratories fulfilling routine gas analysis
• Implementation, use and development of methods and International Standards for analysis of gases and for the performance benchmarking of natural gas measurement
• Liaison and negotiation with world experts in gas analysis on International Standards drafting.
• Principal author of ISO 10723:2012 – Natural Gas – Performance evaluation for analytical systems
• Design and fulfilment of proficiency testing schemes and dissemination of results for the assessment of third party laboratory performance in the analysis of gases and natural gas.
• Independent assessment and resolution of gas quality measurement discrepancies across custody transfer metering points through audit, inspection and performance evaluation
• Inspection and audit of the gas quality measurement chain from sampling through calibration, analysis, quality control, data reduction and report production
• Validation of gas measurement packages to meet business critical fiscal metering standards, sales gas agreements, health and safety legislation and European/International laws that may be applicable
• Liaison between national gas transporters and government regulators in the agreement of methods and presentation of performance data for compliance with prevailing statutory instruments.
• Publication and presentation of basic research and novel developments in natural gas and gas analysis at prestigious international conferences, symposia and distinguished journals