Air Monitoring
the organisation under which the gas mixture is supplied. It is also a good idea to keep on fi le a copy of the laboratory accreditation certifi cate so that it can be made available to auditors. Be suspicious of a certifi cate of analysis which makes reference to ISO 17025 but does not feature the mark of a national accreditation body.
There are two main ways that commercial gas companies assign a certifi ed value to a mixture of gas. One is by measuring the weight of gases added to the cylinder during the fi lling process. Traceability by weight involves comparing the weight of gas in the cylinder, via the aforementioned unbroken chain, to a weight that has been compared to the standard SI mass. If the manner in which these comparisons are made is documented and subject to audit, then, depending on the type of gas mixture, this can be an acceptable way to obtain traceability of the measurements taken to produce the gas mixture.
A second method is by analysing the contents of the cylinder after it has been prepared. Traceability is derived via a series of comparisons between gas samples from the fi lled cylinder, with gas sampled from a primary reference mixture (PRM) prepared by a national standards institute. Primary standard mixtures (PSMs) are maintained within the institution that made them and are used to produce the PRMs used by commercial gas companies as a comparison to certify their gas mixtures by analysis. National standards institutes all prepare primary reference materials by weight, thus forming the link with the SI unit of mass under tightly controlled and measured conditions of temperature, humidity and pressure.
When these comparisons are undertaken by a laboratory within the scope of its ISO 17025 accreditation awarded by a national accreditation body, it is considered traceable in accordance with the ILAC (International Laboratory Accreditation Cooperation) policy.
Regulatory Compliance
Having looked at the main routes of traceability for calibration gas mixtures, we can now link these to requirements set out in the EN 14181 standard.
For quality assurance levels QAL1, QAL2, and the annual surveillance tests (AST), the EN 14181 standard is clear in its prescription of calibration gas standards. For these aspects of compliance it is necessary to select a gas mixture which has been certifi ed within the scope of an ISO 17025 accredited laboratory. That means that the gas mixture must have been certifi ed analytically by comparison to a primary reference material.
When selecting gas mixtures for these applications, look for the following sign that it has been certifi ed within the scope of an ISO 17025 accredited laboratory. Look for the mark of the national accreditation body awarding the accreditation to the laboratory, and the number of the certifi cate awarded to
The calibration of analysers using binary mixtures can often lead to errors in the analysis of stack gases due to cross-sensitivity effects occurring within analysers, hence the value of these products in all aspects of EN 14181 compliance. Calibration using binary mixtures often requires a large number of calibration cylinders and often do not take into account cross
ISO 17025 accredited stack teams must calibrate instruments used for MCERTS testing or for carrying out EN 14181 – QAL2 or AST parallel measurements using gases that are traceable according to the policy of ILAC. If a multi-point gas divider is used to reduce the number of calibration gases required to make a calibration curve, the gas divider must also be calibrated by an ISO 17025 accredited laboratory that has this function within the scope of its accreditation.
ISO 17025 accredited stack teams must also check the span of instruments whilst undertaking QAL2 monitoring work. Working span gases that have traceability not according to ILAC policy are allowed since the purpose is to verify that the traceable calibration is still valid.
For operators needing to comply with the QAL3 element of EN 14181, traceability according to the ILAC policy is not strictly necessary, as stability of the gases is the primary requirement. Gases are used only as control gases and not used to calibrate the instrument. However, it is prudent that these control gases are of suitable quality to give consistent measurements that validate the instrument remains within the Shewart or Cusum control limits, and also produce concurrent results with the QAL2 or AST parallel measurements. Gas mixtures certifi ed outside an ISO 17025 scope are deemed acceptable for QAL3 work.
As suppliers of calibration gas mixtures continue their efforts to serve customers in the fi eld of emissions monitoring, and facilitate compliance with legislative requirements, it’s inevitable that new product offerings and new solutions will come on line.
The last few years have already seen the availability of multi- component mixtures for emissions monitoring certifi ed within an ISO 17025 accreditation scope. For example, mixtures with all of the components CO, SO2
, NO and CO2 in the same cylinder.
5
sensitivity effects. Such errors due to cross sensitivity can also prove expensive during any emissions trading process.
Another positive change is the advancement in cylinder preparation and treatment technology, resulting in shelf lives up to 10 years for some mixture types. Frequent gas cylinder changeovers are burdensome for any organisation, not least because of the cost of gas mixtures, the amount of site work involved, and administrative implications. Also, when working with any type of control chart, cylinder changes bring another added complexity, so it is easy to see the value of these developments to all parties involved in compliance work.
References:
Source Testing Association (STA) Quality Guidance Note QGE- 005-2013 - Traceability in Calibration Gases
The Source Testing Association
The Source Testing Association (STA) was established in 1995 the membership comprises representation from process operators, regulators, equipment suppliers and test laboratories. The STA is a non-profi t making organisation.
The STA is committed to the advancement of the science and practice of emission monitoring and to develop and maintain a high quality of service to customers.
Its aims and objectives are to:
(i) contribute to the development of industry standards, codes, safety procedures and operating principles;
(ii) encourage the personal and professional development of practicing source testers and students;
(iii) maintain a body of current sampling knowledge; (iv) assist in maintenance of a high level of ethical conduct;
(v) seek co-operative endeavours with other professional organisations, institutions and regulatory bodies, nationally and internationally, that are engaged in source emissions testing.
The Associations headquarters are based in Hitchin, Hertfordshire with meeting rooms, library and administration offi ces.
The Association offers a package of benefi ts to its members which include: •Technical advice relating to emission monitoring •Conference and exhibition opportunities •Seminars and training on a variety of related activities •Representation on National, European and International standards organisations •Training in relation to many aspects of emission monitoring •Liaison with regulators, UK and International, many of whom are members.
Stack VOC Determination using a Portable, Cutting Edge Analyser
The problem - Emissions of Volatile Organic Compounds (VOCs) from industrial chimneys are becoming an issue of global importance, and to posess accurate knowledge about how to test VOC is a wise strategy. VOC emissions are quantifi ed and monitored according to standard EN 12619, using an FID analyser which uses hydrogen and other reference gases in pressurised cylinder. Operators must then approach the sampling point, often placed several meters from the ground, climbing chimneys of industrial settlements with instruments and cylinders. Is it possible to make this job easier and safer?
Using the Polaris FID analyser, from Pollution Srl (Italy), it is possible to carry out VOC monitoring according to EN 12619 without lifting accessories and heavy weights typically involved with FID analysers.
So far, the portability of such analysers was a feature of FID designed for fugitive emissions from valves, fl anges, gaskets, pumps or compressors monitoring. Moreover, when
VOCs are measured in chimneys according to EN 12619, the analyser must be much more robust and fully heated to 180°C, leading to increase in size and weight. Polaris’ FID analyser complies with this standard regulation, but the real breakthrough is the unmatched portability and the next generation technology.
Polaris FID is a new concept and incorporates these important features: two rechargeable batteries that last more than three hours; a zero air cylinder for 10 hours of continuous measurement; a span gas cylinder useful for tens calibrations and, last but not least, an advanced metal hydrides cartridge for hydrogen storage to fuel the fl ame detector. However, the hydrogen source is not the usual pressurised cylinder, but a small steel cartridge that weighs only 500 grams, and which stores hydrogen for 30 hours of continuous measurements. Furthermore, as hydrogen is chemically bonded to a special metal alloy inside the cartridge, there is no risk of leakage and explosion: hydrogen cylinder will not be a concern anymore.
In conclusion, the Polaris FID incorporates everything needed for a measuring campaign in just 13 kg and a compact body, making it the best choice for the operators who have to climb on the chimneys of industrial settlements easily and safely.
For More Info, email: email:
For More Info, email:
30694pr@reply-direct.com
www.envirotech-online.com IET Annual Buyers’ Guide 2014/15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148
