Innovations in Air Quality Monitoring
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A presentation recently given to the Wesh Air Quality Forum by Duncan Mounsor at Enviro Technology Services Plc
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Innovations in Air Quality Monitoring
- 1. A Selection of Innovations & Developments in Air Quality Monitoring TechnologyDuncan Mounsor – ET Sales & Marketing Director
- 3. Indicative AQ Monitoring – ET TrafficBOx.
- 4. Dare To Be Different! - Opsis System.
- 6. “Chemi” NOxanalysers are all relatively large, bulky, highly sensitive and precision instruments.
- 7. They need a large enough enclosure to house all the necessary kit (analysers, pump, cylinders, comms, air-conditioners etc.)
- 11. Small footprint.
- 12. Easier to site.
- 13. Secure.
- 15. An “indicative” Air Quality screening tool.
- 16. Dimensions: H=700mm, W=400mm, D=200mm
- 18. Wall or lamp-post mounted.
- 19. Multi-parameter monitoring. Modules for NO2, PM10, O3, CO, NH3, Noise etc.
- 20. Fast response, 1,5, 10, 15, 30, 60 min averages.
- 21. Good correlation with reference methods.
- 22. Metal-oxide semiconductor sensors (NOT electrochemical).
- 26. Need frequent LSO visits (2-4 weeks)
- 27. Need frequent calibration visits (4 weeks)
- 28. Need service and maintenance contracts.
- 29. Take up a lot of operator time.There is an alternative!
- 30. Dare To Be Different – Opsis open-path AQM
- 31. Dare To Be Different – Opsis open-path AQMAll of this…
- 32. Dare To Be Different – Opsis open-path AQM Can be replaced by just this...... Measures NO2, SO2, O3, BTEX and many others!
- 33. Dare To Be Different – Opsis open-path AQMSt. Thomas Opsis AQM Site – Swansea.
- 35. Path averaged measurement, very representative of overall air quality in an area, not just at one point.
- 36. Multi-gas monitoring. NO NO2 SO2 CO O3 BTEX NH3 etc.
- 37. Other gases i.e. Formaldehyde, Styrene can be added.
- 38. No LSO visits.
- 39. Calibration only every 6 months.
- 43. Simple, robust, rugged design – time proved principle.
- 44. Measures PMas hourly averages (+ option RTM).
- 45. PM10 or PM2.5 measurement,
- 46. Filter tape lasts for 2 months, no site visit required in-between.
- 47. Substantially lower purchase and operational costs.
- 48. Very simple to install, set-up and operate.
- 50. ETTrafficBOx – Flexible indicative AQM screening tool.
- 51. Opsis open-path – The future of AQM???
- 53. www.et.co.uk
Notes de l'éditeur
- Compared to other technology sectors (for instance IT), air quality monitoring is a very “conservative” market, and the take-up of new technology often very slow, even if there are clear cost-benefit advantages for doing things differently.
- This presentation will look at just a few innovative ideas and alternative technologies and I hope it will provide a greater insight for you.
- ChemiluminescentNOx analysers have been around for 30+ years. Although the electronics have changed (there were no microprocessors in analysers just 20 years ago), the actual measurement and detection systems within them have hardly changed at all. Reaction cell, ozone generator, moly-con etc.Chemiluminescence is still regarded as the “Gold Standard” for ambient NOx monitoring world-wide and is in fact an ISO reference method.They will be with us for a long time to come although there are other thoroughly proven and well established techniques like DOAS which we will come back to.In the 20 years I have been at ET, I’m yet to see any manufacturer in the world manage to make a NOx analyser much smaller. Lift the lid on one and you will see why. They are jam packed with modules, all of which necessary for the chemiluninecence reaction to take place.
- Although at first glance this may not look any different than other roadside enclosures, look again. It is very “skinny”. Only 300mm deep in fact. This makes for a very small, unobtrusive footprint. They can be far easier to site than more common enclosures.
- How do we do it? Simple, just mount the analyser vertically rather the typical horizontal approach. The analyser performs just as well and means we can save lots of space! We leave enough in there though for gas cylinders, regulators, pumps, modems, etc. Just a bit of clever packaging really!
- When you would like to measure NOx and maybe one or two other pollutants, but don’t need the precision and overall accuracy of “reference method analysers” such as chemiluminescentNOx, then the TrafficBOx could be of interest?There have been tremendous improvements in gas sensor technology over the last decade and sensors such as metal-oxide semiconductors can now measure compounds such as NO2 down to roughly the same levels of detection as chemiluminescence (around 1 ppb). With a range of up to 500 ppb they lend themselves well to air quality monitoring. True the sensors need replacing every couple of years and don’t offer the repeatability and precision compared to say chemiluminescence, but they are excellent for “indicative” monitoring and far more useful than diffusion tubes as you can see what is happening minute by minute, rather than waiting a month or two for lab analysis and then just monthly mean.We can add PM10 with an optical laser backscatter system. Again, not perfect, but useful for indicative purposes.Other sensors can be added for gases such as O3, CO and NHS.All wrapped up in a neat package with data logging, communications and software for analysis/data export.
- When you would like to measure NOx and maybe one or two other pollutants, but don’t need the precision and overall accuracy of “reference method analysers” such as chemiluminescentNOx, then the TrafficBOx could be of interest?There have been tremendous improvements in gas sensor technology over the last decade and sensors such as metal-oxide semiconductors can now measure compounds such as NO2 down to roughly the same levels of detection as chemiluminescence (around 1 ppb). With a range of up to 500 ppb they lend themselves well to air quality monitoring. True the sensors need replacing every couple of years and don’t offer the repeatability and precision compared to say chemiluminescence, but they are excellent for “indicative” monitoring and far more useful than diffusion tubes as you can see what is happening minute by minute, rather than waiting a month or two for lab analysis and then just monthly mean.We can add PM10 with an optical laser backscatter system. Again, not perfect, but useful for indicative purposes.Other sensors can be added for gases such as O3, CO and NHS.All wrapped up in a neat package with data logging, communications and software for analysis/data export.
- Measure up to 6 x gases + dust, or customise choosing whichever sensors you need. PM10 and NO2 an obvious favourite!Housed in a weatherproof case which can be mounted on a wall or lamppost etc.
- Opsis is an open-path, non-contact, optical gas monitoring technology based on differential optical absorption spectroscopy.Three main parts of the system, an emitter (light source), a receiver and a computerised multi-gas spectrometer.No pumps, sample lines, pneumatics, filters and it requires little or no LSO involvement and calibration only once every 6 months. Perfect!
- One of Swansea City Council’s large Groundhog AURN type stations.
- Picture shows DOAS analyser, and emitter/receiver set.
- System in operation in Swansea measuring NO NO2 O3 BTEX over a 600m open-path alongside main arterial road.
- OPSIS is MCERTS approved for NO2 SO2 O3 and Benzene. UK users include Swansea City, Sandwell MBC, Walsall MBC, Corus and several industrial plants.
- Although the TEOM and TEOM/FDMS is very widely used in the UK, there ARE alternatives!We all know now that the original TEOM unit did not meet the EU equivalency testing criteria and the FDMS was introduced partly to overcome these original under-reading measurement problems.Take a look at the BAM1020.BAM stands for beta-attenuation mass monitoring. BAM’s or beta-gauges, have been around for 25+ years.Well before the TEOM, and now, well after it!Well proven technology, well tested (US-EPA, TUV, CARB etc) and more importantly “shown to meet equivalence criteria set out in the UK equivalence programme for monitoring of particulate matter” for PM10. Just like the TEOM/FDMS.The BAM1020 PM2.5 system has also been tested by BV/TUV for CEN equivalence and will be certified during summer 2010.
- Due to the design of the beta-attenuation measurement principle, the BAM has a base resolution of 60 minutes. In other words, it records hourly averages of PM10 or PM2.5. For many urban applications this is fine as the UK/EU reporting frequency for PM10 is a 24 hour average.For those wanting a faster resolution, there is a real-time module (RTM) which is a simple bolt on to the BAM inlet. This is a laser back-scatter unit and enables 1, 5, 15, 30 minute measurement resolution as well as the standard BAM hourly average.
- Due to the design of the beta-attenuation measurement principle, the BAM has a base resolution of 60 minutes. In other words, it records hourly averages of PM10 or PM2.5. For many urban applications this is fine as the UK/EU reporting frequency for PM10 is a 24 hour average.For those wanting a faster resolution, there is a real-time module (RTM) which is a simple bolt on to the BAM inlet. This is a laser back-scatter unit and enables 1, 5, 15, 30 minute measurement resolution as well as the standard BAM hourly average.