The extended shelf-life of analytical gases is particularly useful in emissions testing and monitoring applications because such applications typically use small quantities of gas for each calibration. Analysts also benefit from increased peace of mind when purchasing calibration mixtures that stay stable for considerably longer.
As well as increasing the shelf-life of gas mixtures, the specialty gas industry has expanded its range of top grade calibration mixtures. These mixtures provide an assurance of accuracy in even the most demanding analytical applications and come with ISO 17025 certification, fulfilling UKAS and other equivalent European standards.
The extended range includes mixtures with components commonly used in emissions monitoring applications, such as nitrogen oxides, sulphur oxides or carbon monoxides, at ultra low concentrations, down to low ppb levels, in air or in nitrogen, in order to achieve the most accurate calibration possible.
Making the right choice Choosing the right gas mixture for each analytical calibration can sometimes be difficult. Gas analysts need to ensure that the components that make up the mixture are high quality, as this will minimise uncertainties and ensure that the measurements taken are of the highest accuracy. With this in mind, an easy-to-use online tool has been developed, which enables the user to select bespoke mixtures comprising only the highest quality gases, which come with quality certificates and are fully traceable.
All the analyst needs to do is specify some simple data including the preferred cylinder size, mixture type and composition. This kind of tool is increasingly vital in the fast-moving world of emissions monitoring and control, where fast and accurate analysis across a range of emissions is required.
Today’s emissions monitoring systems are capable of making accurate analyses for all emissions regardless of their reactivity or their concentrations. Their improved accuracy is in part due to improved access to top grade calibration gas mixtures that stay stable for longer. In the field of emissions monitoring, it is now possible to achieve precise analyses for reactive gases such as HCl emissions, against average daily values of 10mg/m3, as specified in Annex V of the Waste Emissions Directive.
Selecting the right equipment In the drive to improve accuracy in the field of gas analysis, there is always room for further improvement. For example, care is needed when selecting the right equipment. While expert advice is sometimes needed to make the right choice, analysts can now use an online tool to browse and select the equipment they need. By completing the online criteria - requesting details of a variety of variables about the specific application - the analyst can select the right equipment and eliminate any possibility of error.
For example, it may be necessary to maintain a precise outlet pressure throughout the use of the cylinder, even when inlet pressure varies. Taking account of such criteria is vital and can have a significant effect on the accuracy of the calibration and therefore of the measurements given. The right choice of material can also be crucial; for safety, purity or compatibility reasons. When using corrosive gases, for example, only stainless steel equipment should be used and when oxygen or oxidizing gas mixtures are being used, brass equipment is preferred.
Of course, it can be easy to overlook one or more of the
variables involved in equipment selection. Among the most
common errors made when choosing equipment is failing to recognise that a double-stage
regulator is needed or specifying equipment which will provide the wrong outlet pressure. Using the new online
equipment selector, all the thinking is done in
advance, so all the user needs to do is answer a simple set of questions and a recommendation for the best equipment model is made.
Such smart solutions are performing an increasingly important role in improving the accuracy and reliability of gas analysis and they will continue to do so in the future.
For more information about Air Products’ Experis® range of gases and gas handling equipment, ring 0845 777 8800 or email
getgas@airproducts.com. For expert advice on the selection of gases and the equipment, the online equipment selector can be viewed at www.
airproducts.co.uk/equipmentselector and the online mixture selector can be viewed at
www.airproducts.
co.uk/experismixtureselector.
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