John Carney Mark Phelps Andrew Tolley American Ecotech Roadside Monitoring Nephelometers 101 Light trap Sample outlet Sample inlet Temp RH sensor Measurement bench Reference shutter motor ID: 741985
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Slide1
Utilizing Nephelometers for Near RoadsideJohn CarneyMark PhelpsAndrew TolleyAmerican EcotechSlide2
Roadside MonitoringSlide3
Nephelometers 101
Light trap
Sample outlet
Sample inlet
Temp RH sensor
Measurement bench
Reference shutter motor
PMT,HV supply,
pre amp
PMT signal
LED module
Pressure sensorSlide4
Nephelometer ReadingsSlide5
Total light extinction = light scattering + light absorption • Light scattering by particles (bsp) - Urban visibility field studies
indicated that particles ≤ to 2.5 microns in aerodynamic diameter (PM2.5) cause the vast majority of light scattering.• Atmospheric, or Rayleigh scattering (bRayleigh)
is natural scattering not related to air
particulate.
•
Light absorption
-
due
to particles and gases, and is determined by analysis of elemental carbon
.
A
nephelometer
measures the light scattering component of light extinction.Nephelometers 101Slide6
Inverse Megameter (Mm-1) is the direct measurement unit for visibility impairment data. It is the amount of light scattered and absorbed as it travels over a distance of one million meters.Visual range (VR)
- Visual range is an expression of visibility impairment defined as the distance in miles or kilometers at which a large, black object just disappears from view. Visual range values are calculated from direct measurement data, or are estimated directly by observers. Visual range can be calculated from extinction data as follows: Visual Range (km) = 3912 / bext(Mm-1)
Mass Concentration (mg/m
3
µg/m
3
)
Nephelometer UnitsSlide7
The first generation in LED Light Source introduced in 2002
Evolution of LED Light Source
Three WavelengthSlide8
Next Generation of LED Lightsource
Evolution of LED Light SourceSlide9
AdvantagesStable light intensity Stable light wavelength generationBandpass filters not requiredNegligible thermal interference during measurementMinimal mthly maint. (<10
minutes per month!)
Evolution of LED Light SourceSlide10
Disadvantage – Geometry of light source and diffusion lens led to an uneven light distribution within measurement cell
Evolution of LED Light Source
Result – Over estimation of scattering coefficients (by up to 10%)Slide11
Opal Diffuser in front of LED array
Evolution of LED Light Source
Result – Light intensity approaching Lambertian distribution resulting in negligible error.Slide12
New Generation of LED LightsourceFewer LEDs – Three lamps per wavelengthCompact Light SourceFurther reduction in measurement bench heating (between sample and ambient temperature)User adjustable intensity pots (extend lifetime of light source)Fully field serviceableBackwards compatible with older units.
Evolution of LED Light SourceSlide13
Near Roadside MonitoringDust MonitoringForest Fire/Smoke MonitoringPM Correlation MonitoringSolar Energy Site Assessment and Operation
Field ApplicationsSlide14
Near Roadside
I-40 Station – Raleigh
Gas Analyzers (NOx, Ozone)
Particulate Monitors (BAM,
Aethalometer
, Ultrafine)
Samplers (passive, TSP)Slide15
InstallationSlide16
InstallationSlide17
Preliminary DataSlide18
Preliminary DataSlide19
Preliminary DataSlide20
Preliminary DataSlide21
Dust Monitoring
Sydney Dust Storm – September 2009Slide22
New South Wales EPA Air Monitoring NetworkSlide23
Field ApplicationsSlide24
Field ApplicationsSlide25
Field Applications
Victoria EPA Forest Fire alert categories based on PM10 and visibilitySlide26
Smoke Monitoring
Pollutants
Ozone
O3
Ozone
O3
Nitrogen
dioxide
NO2
Visibility
NEPH
Carbon
monoxide
CO
Sulfur
dioxide
SO2
Particles
PM10
Particles
PM2.5Averaging Periods1-houraverage
4-hour
rollingaverage1-houraverage1-houraverage
8-hour
rollingaverage1-houraverage
24-hourrolling
average24-hourrollingaverageSydney East
Randwick
2.51.40.4
0.37
0.4
24
Rozelle
2.4
1.3
0.5
0.46
0.3
24.9
Lindfield
2.2
1.2
0.5
0.35
0.1
19.8
Chullora
2.5
1.1
0.9
0.39
0.4
0.1
23.4
12.2
Earlwood
2.8
1
0.8
0.43
25
11.6
Sydney North-west
Richmond
2.9
1.4
0.4
1
0
28
17.4
St Marys
4.1
1.8
0.7
5.43
34.7
Vineyard
2.7
1.3
0.3
0.52
0
24.6
Prospect
2.9
1.4
0.6
0.74
0.2
0.1
27.5
Sydney South-west
Bargo
3.7
1.7
0.7
13.12
0.2
Bringelly
3.1
1.5
0.3
2.16
0.1
31.9
Camden
3.1
1.5
0.4
3.17
0.3
37.4
24.7
Campbelltown West
3.2
1.5
0.6
2.2
0.6
0.1
26.4
Liverpool
2.9
1.3
0.6
0.68
0.5
29.1
19.4
Oakdale
4.6
2.9
0.6
11.16
72.3 IllawarraWollongong3.42.60.31.360.50.131.628.7Kembla Grange420.45.02 66.9 Albion Park Sth4.42.40.66.23 0.162.6 Lower HunterWallsend2.31.40.40.51 0.122.313.1Newcastle2.31.80.50.390.10.927.1 Beresfield1.70.90.70.78 035.5 Central CoastWyong2.9 0.20.50.20.122.214.5Central TablelandsBathurst 63.7 North-west SlopesTamworth 12.7 South-west SlopesAlbury 27.9 Wagga Wagga Nth 72.645.1Upper Hunter - MuswellbrookMuswellbrook 0.5 0.132.313Upper Hunter - SingletonSingleton 1.1 0.128.910.8 Air Quality Index VERY GOODGOODFAIRPOORVERY POORHAZARDOUS
New South Wales Air Quality October 20, 2013 8:00 – 9:00 AEST Brush Fire EventNephelometer – hourly average based on 1 or 5 minute (high frequency) data, capturing smoke event as it occursSlide27
Smoke MonitoringSlide28
Portable FunctionalitySlide29
Correlation of Nephelometers
Correlation of PM2.5 measurements and scattering coefficients
Puget Sound Clean Air Agency Study – Residential Area
Collocated Instruments:
American Ecotech Nephelometer
Radiance Research (RR) Nephelometer
Partisol (FRM) for PM
2.5
TEOM with PM
2.5
head
TEOM (FDMS-TEOM) PM
2.5
head
BAM 1020 PM
2.5Slide30
FRM vs. Nephelometer
Particulate MonitorsSlide31
FDMS TEOM vs. Nephelometer
Particulate MonitorsSlide32
BAM vs. Nephelometer
Particulate MonitorsSlide33
ResultsNephelometer correlates well(r2 > 0.94) with:The US Federal Reference MethodFDMS-TEOMFEM Beta Attenuation Monitor
Particulate MonitorsSlide34
Continuous Correlation – Aurora Neph and BAM-1020
Particulate MonitorsSlide35
Renewable Energy Field
Courtesy of yesRenewablesSlide36
Site Evaluation involves up to a year long study of site conditions. Parameters to measure include:Solar IntensityLight DurationCloud CoverLight Scattering
Solar Site EvaluationSlide37
Solar Tower
Courtesy AMBLSlide38
Evaluate degree of light scattering of both incoming light and reflected light.Need to evaluate scattering at several levels covering the height of the planned tower
Solar Site EvaluationSlide39
Sue Kimbrough and Richard Snow – USEPA Office of Research and Development
Acknowledgments Slide40
Email: jcarney@americanecotech.comWeb: www.AmericanEcotech.com
Contact information