Calibration Gases for Ambient Air Monitoring
The measurement of air quality in the UK is subject to increasing legislation and public scrutiny, and it is therefore increasingly important that monitoring equipment is properly calibrated.
The UK government's guidance on automatic air pollution monitoring for Local Authority review and assessment of air pollution specifies that calibration gases must be certified to ISO17025. This is to ensure data is traceable to national metrology standards and that the overall uncertainties for pollution data are within specified limits.
This standard is an internationally recognised standard for demonstrating the competence of calibration and testing laboratories, and significantly exceeds the requirements of the more common ISO9000 standard. The ISO17025 standard defines what is required of an organisation in terms of technical competence, staff and resources in order to produce acceptable quality of results for a defined set of processes.
AEA Energy & Environment and Air Liquide (UK) Ltd have combined their capabilities to offer traceable calibration gas mixtures directly to organisations undertaking air pollution measurements. Gases produced by Air Liquide are calibrated by AEA and are supplied, often from stock, complete with an ISO17025 certificate of calibration.
ISO17025 Certified Gases
Currently, mixtures are available with certification for the following gas mixtures:
| Mixture | Range | Expected Uncertainity |
| Carbon monoxide in air | 5-550ppm | ±2% |
| Nitric oxide in nitrogen | 100-200ppb | ±4% |
| 200-1000ppb | ±3.5% | |
| Nitrogen dioxide in air | 100-200ppb | ±4.5% |
| 200-1000ppb | ±4% | |
| Sulphur dioxide in air | 100-200ppb | ±3% |
| 200-10000ppb | ±2.5% |
Cylinders are available in both L10 (10 litre) and L40 (40 litre) sizes and can be delivered directly to air monitoring stations, subject to suitable access.
ISO17025 Certified Gases
| Binary Gas Mixtures | ||||
Gas |
Matrix |
Concentration Range |
||
Carbon Monoxide | Air |
20 & 40ppm |
||
Sulphur Dioxide | Air |
150 & 450ppb vol |
||
Nitrogen Dioxide | Air |
200 & 450ppb vol |
||
Nitric Oxide | Nitrogen |
200 & 450ppb vol |
||
10ltr and 40ltr aluminium cylinders
Available with recertification by AEA Technology to EN ISO 17025 accreditation standard
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