Štefan Ošlaj August 2020 Aethalometer AE33 Training outline
1. Basics about Aethalometer
2. Applications example
3. AethNET
4. Installation
5. User interface & data
structure
6. Quality control
7. Open discussion 1. Aethalometer basics Black carbon (BC)
• produced by incomplete combustion of carbonaceous fuels ➢good indicator of primary emissions Aerosol Sources Effect characteristics
Ferrero et al, EST, 2018 Black Carbon : Formation during combustion Emissions of Black Carbon
• BC / (kilogram fuel) is unpredictable * 10³
• Quantity of fuel → CO2 • Quality of combustion → BC Double role of Black Carbon Air quality Climate effect
Top of the atmosphere W/m2
V. Ramanathan, G. Charmichael, Nature Geosci (2008) 221 Total BC forcing: direct + indirect 2 1,1 W/m (Bond et al 2013) Emissions of Black Carbon must be measured
Lord Kelvin, 1824-1907 “If you can not measure it, you can not improve it.” “To measure is to know.”
BC must be measured
8 The Aethalometer™ - since 1979
• Draw air sample continuously through filter, collect aerosol. • Illuminate, measure rate of decrease of optical transmission. • Calculate rate of increase of ‘Attenuation’ (‘ATN’) • ATN is proportional to loading of Black Carbon • Calculate concentration of BC in air stream.
9 Basic calculations
Reference I0
ATN = ln (I0 / I) BC Sensing I
Light Source Light Detectors
Filter with Sample babs ~ ATN
• Collect sample continuously (Filter Gradually becomes darker and darker) • Optical absorption ~ change in ATN. • Measure optical absorption continuously : λ = 370 to 950 nm. • Convert optical absorption to concentration of BC: BC (t) = b(t) / • Real-time data: 1 s -1 min Basic equations
푺 × ∆풂풕풏 Basic equation 푩푪 = 푭 × ∆풕 × 흈풂풊풓
Sigma & multiple 흈풇풊풍풕풆풓 = 흈풂풊풓 × 푪 (Weingartner et al., 2003) scattering parameter 퐶 = 1.39 (Teflon, M8060)
Loading effect 푩푪 = 푩푪Τ ퟏ − 풌 × 푨푻푵 compensation 풄풐풎풑
푭풊풏 = 푭풐풖풕 × ퟏ − 휻 Measured leakage Leakage factor 휁 = 0.01 (Teflon, M8060)
푺 × 횫풂풕풏ퟏ Final equation 푩푪 = 푭ퟏ ퟏ − 휻 × 흈풂풊풓 × 푪풕풆풇풍풐풏 × ퟏ − 풌 × 푨푻푵ퟏ × 휟풕 Basic equations
Final equation 푺 × 횫풂풕풏 푩푪 = ퟏ 푭ퟏ ퟏ − 휻 × 흈풂풊풓 × 푪풕풆풇풍풐풏 × ퟏ − 풌 × 푨푻푵ퟏ × 휟풕 S 푩푪
휟풕
횫〖풂풕풏〗_ퟏ 풌 F
흈_풂풊풓 휻 푪_풕풆풇풍풐풏 Flow diagram Wide Dynamic Range of actual measurements
Clean air from ocean: BC < 50 ng/m³
Clean air : Berkeley, California 1,400 370 470 520 590 660 880 950 Highly Polluted Air : BC >100 µg/m³
1,200 Polluted Air : Kolkata, India 1,000 140,000 880 800 120,000 Maximum :
600 100,000 >100 μg/m³ BC, ng/m3 400 Minimum : 80,000 0.03 μg/m³ 200 ng/m3 60,000
0 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 BC, 40,000 17 ~ 18 July 2011 20,000
0 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 16 Dec 2009
14 Aethalometer® Real time measurements
Time series from roadside location in London : 3 months of data on 5-minute time-base Problem: Derive meaningful conclusion from 19,125 data points.
Data courtesy of P. Quincey, NPL, UK Gather into overlays : 12 weekly cycles of 5-minute data Loading effect compensation Tape advance New tape advance
As the loading of particles on the filter Linear reduction of the instrumental increases, the existing particles may response due to loading of the filter “shadow” the freshly-collected ones. fiber. Jump at the tape advance (Virkkula 2007) 8000
jump @ filter-tape Smoothed data advance 20000 7000 Linear fit BC measured at 370 nm 18000 non-compensated jump @ filter-tape 6000 compensated advance BC 16000 0 5000
14000
) 3 12000
) 4000 3
10000 (ng/m
3000 (ng/m
8000 BC dBC/dATN = slope of the fitting line BC 6000 2000
4000 1000 2000 Fitting range 0 0 4800 4850 4900 4950 5000 5050 5100 5150 5200 0 10 20 30 40 50 60 70 80 90 100 t (min) ATN BC (reported) = BC (zero loading) · { 1 - k · ATN } . • ambient data – no dependence of BC on ATN • slope k variable: site, source, aerosol age, composition • need to determine it dynamically – do not assume, reather measure Loading effect compensation
1. Determination of compensation parameter k(λ) 2. Calculation of compensated BC:
퐵퐶 = 퐵퐶1/(1 − 푘 × 퐴푇푁1)
5000
4000 Slope dBC/dATN
) 3
3000 (ng/m
BC 2000
1000 non-compensated data compensated data 0 0 10 20 30 40 ATN Loading effect compensation DualSpot method
TM IR, 1 second the DualSpot method raw BC1 raw BC2
80000 compensated BC
) 3 60000
40000
20000 BCconcentration (ng/m
0 2000 3000 4000 time (sec) Two parallel spots with different flow, therefore different loading and attenuation.
Calculate loading compensated BC and k! Loading effect compensation – DualSpot method
Filter with Sample Reference I0 ATN = ln (I / I ) BC Sensing I1 1 0 1 ATN2 = ln (I0 / I2) Sensing I2 Light Source Light Detectors
Two parallel spots with different flow, therefore -> different loading and attenuation. Tape advance New tape advance time max ATN reached
ATN ATN ATN
babs babs babs
BC BC BC Loading effect depends on the mixing state
0,006 Spectral fingerprint of parameter k 0.008 0,005 Fresh aerosols - Klagenfurt (Austria) March 2012 0.007 Aged aerosols - Payerne (Swiss) June-July 2012 0,004 0.006
0,003 0.005 Winter 2012 campaign Roadside site: 0,002 0.004 Klagenfurt, Austria
370 nm k 0.003 0,001 470 nm 520 nm 0.002 EMEP 2012 campaign 0,000 590 nm 660 nm 0.001 Background site: 880 nm Compensation parameter k parameter Compensation -0,001 Payerne, Switzerland 950 nm 0.000 -0,002 -0.001 18.6.2012 23.6.2012 28.6.2012 3.7.2012 8.7.2012 300 400 500 600 700 800 900 1000 time (nm)
Drinovec, L., Gregorič, A., Zotter, P., Wolf, R., Bruns, E. A., Prévôt, A. S. H., Petit, J. E., Favez, O., Sciare, J., Arnold, I. J., Chakrabarty, R. K., Moosmüller, H., Filep, A., and Močnik, G.: The filter-loading effect by ambient aerosols in filter absorption photometers depends on the coating of the sampled particles, Atmos. Meas. Tech., 10, 1043-1059, 2017. Compensation depends on the aerosol type
0.003 AE33 compensation EMEP summer campaign 0.002 parameter 2012 0.001 0.000
-0.001 Paris, Gif sur Yvette
880 nm 880 k site operated by LSCE, CNRS/CEA/UVSQ - -0.002 -0.003 -0.004 Compensation parameter -0.005 and sum of anorganic 30 secondary aerosol + organic aerosol correlate 25 ACSM (Aerosol Chemical well. Speciation Monitor) 20
15 We can discriminate
+ ORG) / BC 4 between fresh & old: 10
+ NH local & regional.
4 5 (SO 0
13.6.2012 20.6.2012 27.6.2012 4.7.2012 11.7.2012 Loading effect compensation
• Algorithm sensitivity ‣ Temperature → warming up instrument to room temperature ‣ Humidity → no fast humidity & T changes ‣ Input pressure → constant pressure
• Setting kmin & kmax values: ‣ Default settings: -0.005 < k < 0.015 0,006
‣ Expected values: 0 < k < 0.010,005
0,004
0,003
0,002 370 nm 0,001 470 nm 520 nm 0,000 590 nm 660 nm 880 nm Compensation parameter k parameter Compensation -0,001 950 nm -0,002 18.6.2012 23.6.2012 28.6.2012 3.7.2012 8.7.2012 time Source apportionment: Biomass smoke vs. diesel
• measure attenuation with the Aethalometer
• absorption coefficient - babs
• for pure black carbon: babs ~1/λ • generalize Angstrom exponent: 휶 풃풂풃풔~ퟏ/흀
diesel: α ≈ 1 biomass-smoke: α ≈ 2 and higher
• Sandradewi et al., A study of wood burning and traffic aerosols in an Alpine valley using a multi-wavelength Aethalometer, Atmospheric Environment, 101–112, 2008. • Zotter et al.: Evaluation of the absorption Ångström exponents for traffic and wood burning in the Aethalometer- based source apportionment using radiocarbon measurements of ambient aerosol, Atmos. Chem. Phys., 17, 4229- 4249, 2017. Source apportionment – “Aethalometer” model
Reported in data file
Jereb et al.: Exposure to Black Carbon during Bicycle Commuting–Alternative Route Selection, Atmosphere, 9, 2018. Introduction to Aethalometer AE33
• Multiple wavelengths: absorption: UV-IR, quantitative source apportionment: fossil fuel vs. wood-smoke – BC and CM. • Dynamic loading compensation dual spot compensation algorithm eliminates filter loading artifacts. • Automated QA/QC with zero, optical span checks and flow calibration. • Improved performance: low noise, fast time resolution. • Easily integrates into networks: ease of communication
and maintenance. Drinovec, L., Močnik, G., Zotter, P., Prévôt, A. S. H., Ruckstuhl, C., Coz, E., Rupakheti, M., Sciare, J., Müller, T., Wiedensohler, A., and Hansen, A. D. A.: The "dual-spot" Aethalometer: an improved measurement of aerosol black carbon with real-time loading compensation, Atmos. Meas. Tech., 8, 1965- 1979, 2015. 2. Application examples Applications
Aethalometer® AE33 •BC is a primary product of incomplete combustion
•BC not automatically related to CO2 emission
dpp=20 nm
Application Customer Source apportionment (BCff/BCbb) National AQ networks
Evaluating transport abatement measures Local authorities + national (LEZ) + pollution forcasting due to traffic met authority
Local/Regional transport of air pollution Academic users
Emission studdies Industry (minning, ship emissions..) National AQ networks UNITED KINGDOM
Black Carbon network in UK
(NPL, King‘s College, DEFRA)
• 20 stations in total equiped with Aethalometer • mostly legacy Aethalometer models, that will be completelly exchanged with the new model (AE33) during next few years
Main scope: source apportionment, shipping emissions, trafic restrictions, regional impact, National AQ networks INDIA
ARFI (Aerosol Radiative Forcing over India) NETWORK (implemented by SPACE PHYSICS LABORATORY Vikram Sarabhai Space Centre)
• Approx 42 stations all over India • Around 35 Aethalometers deployed • Discusion for TRADE IN started in January
Main scope: regional aerosol characterization, incorporating the heterogeneities in space, time and spectral domains for periodical and accurate estimates of Aerosol Radiative Forcing over India and to assess the impacts on regional and global climate National AQ networks INDIA
NATIONAL BLACK CARBON NETWORK (Indian Meteorological Dept, Ministry of Earth Sciences)
• 16 stations all over India – turn key solution • Expansion in progress • All stations equiped with AE33, met station, ultra high capacity UPS and Personal Computer • All stations stream data to central server in New Delhi • Phase 2 - MetOne – open issues • Phase 3 – AE - planed
Main scope: Source apportionment, BC impact on local/regional scale, impact on climate change National AQ networks
National AQ networks that already implemented BC analyzers
-USA -CHINA -INDIA -SLOVENIA -CROATIA -FRANCE -UK -GERMANY -BELGIUM, -NETHERLANDS -SWITZERLAND -ITALY -COLOMBIA -ISRAEL -IRAN . . . Local authorities + national met authority
AIRPARIF is an non-profit organization, Biomass smoke over Paris accredited by the Ministry of Environment that runs the air quality network in Paris.
• more than 60 stations (~50 automated) • around 10 mobile stations “Ambient measurements of light absorption by • approx 8 Aethalometers installed agricultural waste burning organic aerosols”
O. Favez et al., J. Aerosol Science 40, 613 (2009) Main scope: Source apportionment, BC concentrations from traffic, impact from local/regional region Local authorities + national met authority
Monitoring air pollution abatement measures Teheran, London,…. Low emission zone
Main scope: impact of the transport to the air pollution in cities, reduction of BC levels to sustainable levels, green cities.. Evaluating transport abatement measures
Ljubljana Low emission zone Local authorities + national met authority
EMISSION FACTOR MEASUREMENTS
퐵퐶 퐸퐹~ 퐶푂2
To estimate a contribution of vehicle type, age, fuel etc…to total PM, using
stationary/mobile method 7-wavelength Aethalometer data - biomass burning plume impact at remote site. Data as recorded
370 430 470 520 590 700 950 Best-fit Baseline 25000
20000
15000
10000 Equivalent ng/m3 Equivalent
5000
0 0:00 6:00 12:00 18:00 0:00
27 June 2008 Local authorities + national met authority MECEDES car chasing project – identification of super emitters Local authorities + national met authority SBC-SL Smart Black Carbon Street Light
DUN
AER VOJ
GOS ZAL
POS
GOL
Background Traffic site Local authorities + national met authority SBC-SL Smart Black Carbon Street Light Live maps (and forecast*)
* Forecasting based on machine learning Local authorities + national met authority Local authorities + national met authority Academic users AMAZONIAN TALL TOWER OBSERVATORY – The German-Brazilian joint project (Max Planck Institute, Instituto Nacional de Pesquisas da Amazônia) • 325m tall tower • In the middle of the rain forrest • 3 x AE33 instruments on site, several Sample Stream Dryers • Nobelov nagrejenec Main scope: Climate change effects, aerosol formations, transport processes of air masses, development of complement traditional climate models Academic users High altitude installations Austria, Switzerland, Nepal, China…
Main scope: impact by regional transport (wild fires, desert storms..) of air pollution, Climate change, Academic users AVIATION FOR SCIENCE (Aerosol, Matevž Lenarčič (pilot)) • An Ultra light plane equiped with modified AE33 • Flights around the globe (2012, 2013, 2016, 2017, 2018, 2019, 2020/21) Main scope: Source apportionment, BC impact on local/regional/global scale, impact on climate change, BC inventory, Industry
“Ventilation On Demand”
“As energy consumption from ventilation fans within an underground mine can account for up to 50 per cent of the mine’s electricity costs, this represents a significant cost savings and minimizes the impact on the environment” Aethalometer – applications web page https://mageesci.com/applications/ 3. AethNET Remote management of single/multiple instruments Example of National Black Carbon network Example of National Black Carbon network
Customizable reports include: server, measurement and data transfer status, plus all BC measurement charts.
49 Remote access
Complete remote management Identical user interface as on the instrument CMD line for poor internet connections
50 Real-time notifications
Real-time alert Daily report. No BC data, no data storage, no remote control Only requirement: instrument and internet access Real-time notifications
Real-time alert Daily report. No BC data, no data storage, no remote control Only requirement: instrument and internet access 4. Installation Installation Installation – NO BUG SCREEN INSTALLED Drying the sample
PERFORMANCE • Sample air flow: up to 5 LPM optimal (16,7 LPM max flow tested) • Drying efficiency: 14 °C reduction of dew
point @ input TD = 22 °C @ 5 LPM • Particle loss: < 4 % • Temperature display accuracy: 0.2 °C • Relative humidity display accuracy: 2%
APPLICATIONS • Operation on aircraft, balloons, research towers • Mobile operation on vehicles • Off-grid and portable operations Possible External devices
CO2
T, RH, P
Various inlets PM1-PM10 Additional GPS measured parameters Sample drying efficiency
wind
Neph
5. User Interface and data strucure User interface
• 8.4'' color touch-screen with status indicator LED's • Status de-convolution on home screen • live data access on data screen • Access to log records from last start of the instrument….. User interface / home screen User interface / operation screen User interface / data screen User interface / settings Flow reporting standard
Sample flow is measured by a mass flow sensor.
푻 Mass flow 푉 = 푛푅 × Volumetric flow 풑
Volumetric flow depends on the reporting pressure & temperature. Different flowmeters and instruments use different flow reporting standards. It is always possible to recalculate to other flow reporting standard: 푇2 푝1 퐹2 = 퐹1 Temperature must be reported in degrees K! 푇1 푝2 User interface / settings Flow reporting standard
Volumetric flow recalculation:
푇2 푝1 퐹2 = 퐹1 푇1 푝2 User interface / setup file
Setup file - Changes, saving - Export - Setup file restore
Most important parameters: - Sigma values - Leakage parameter ζ - Max, min k - Flowmeter calibration values - Tape sensor calibration values - Selected flow reporting standard - Auto Clean air test settings 6. User interface / data file
Data file structure:
• Date(yyyy/MM/dd); Time(hh:mm:ss); Timebase;
• RefCh1; Sen1Ch1; Sen2Ch1; RefCh2; Sen1Ch2; Sen2Ch2; RefCh3; Sen1Ch3; Sen2Ch3; RefCh4; Sen1Ch4; Sen2Ch4; RefCh5; Sen1Ch5; Sen2Ch5; RefCh6; Sen1Ch6; Sen2Ch6; RefCh7; Sen1Ch7; Sen2Ch7;
• Flow1; Flow2; FlowC; Pressure(Pa); Temperature(°C); BB(%);
• ContTemp; SupplyTemp; Status; ContStatus; DetectStatus; LedStatus; ValveStatus; LedTemp;
• BC11; BC12; BC1; BC21; BC22; BC2; BC31; BC32; BC3; BC41; BC42; BC4; BC51; BC52; BC5; BC61; BC62; BC6; BC71; BC72; BC7;
• K1; K2; K3; K4; K5; K6; K7;
• TapeAdvCount;
• External devices 6. Quality control Procedures
1. Indoor testing and calibration 8. Leakage test
2. SW update 9. Inlet leakage test
3. Tape change 10. Flow calibartion
4. Stability test
5. Clean air test
6. Verify flow
7. ND test Comparison setup – Aerosol d.o.o. Comparison setup – Aerosol d.o.o. Quality control / flow verification
• Automatic / Manual BGI tetraCal®
Auto flow verification report: 25 May 2013 21:09:27 TSI Mass Flowmeter 4140
External flowmeter measurement: P T Fin 101325 21.11 919 BGI Tetracal flow calibrator is 101325 21.11 2946 recommended 101325 21.11 4912
Flow verification results: During flow check a calibration pad is Flow reporting standard: AMCA 101325 Pa 21.11 °C used. Fin F1 (%) Fc (%) 919 921 (100) 913 (100) 2946 2946 (100) 2946 (100) 4912 4908 (100) 4907 (100)
Flow calibration is needed if difference > 10 % Quality control / leakage test
• Leakage test Leakage (ζ) is measured during instrument operation:
ζ=1-(Fin/Fout)
Average leakage is 1% at 5 LPM (with M8060 tape). It can differ slightly from spot to spot and during the spot loading. After performing leakage test a report is being generated: Manual leakage test report Serial number: AE33-S02-00232 Date and time: 01 Dec 2014 11:21:21 Selected flow: 5000 mlpm Flow through tape: 4700 Flow through calibration pad: 5000 Instrument leakage is: 1.2 %
Leakage should be measured using a low pressure drop calibrator: BIOS is not OK Leakage should be < 10 % Quality control / stability test
• Stability test (without flow) Average 퐵퐶 ± ퟑퟎ 퐧퐠/퐦ퟑ After performing stability test a report Point to point variation of BC (PPBC) is being generated: at 1 s timebase:
푛 1 Stability test report. 푃푃퐵퐶 = 퐵퐶 − 퐵퐶 푛 푖+1 푖 Serial number: AE33-S02-00232 푖=0 Date and time: 02 Dec 2014 11:46:03 Duration: 00:20:00, Timebase: 1 sec, Flow: 0 mlpm PPBC61 < 450 ng/m3 AverageBC PPBC (ng/m3) Spot1 Spot2 Spot1 Spot2 Ch1 -13 -4 261 645 Ch2 -5 -3 357 934 Ch3 -3 8 365 899 Ch4 0 16 348 956 Ch5 -2 11 369 1023 Ch6 -23 -29 402 1118 Ch7 -16 -24 473 1230
Result of stability test is acceptable. Quality control / stability test
• Stability test (without flow)
No flow through the chamber! Quality control / Clean air test
• Clean air test (flow through built-in filter)
• Average BC < 30 ng/m3 • PPBC61 < 550 ng/m3 (point to point variation of BC @ 1 s & 5 lpm)
Automatic clean air test • Performed weekly or monthly • Average BC and PPBC for each chanel and spot are displayed in the log file
After performing clean air test a report is being generated. Quality control / Clean air test
• Clean air test (flow through built-in filter) Quality control / ND test
• ND test – determination of optical sensitivity
Files used to compare: NDtest_AE33-S01- 00074_20130509_161427.dat NDtest_AE33-S01- 00074_20130510_080954.dat Filterset AE33-ND-0002 Old filterset AE33-ND-0002
Optical test slope result: Ch1 s1 0.995 s2 0.993 Ch2 s1 0.983 s2 0.980 Ch3 s1 0.984 s2 0.980 Ch4 s1 0.981 s2 0.978 Ch5 s1 0.979 s2 0.976 Ch6 s1 0.974 s2 0.972 Ch7 s1 0.977 s2 0.975
Slope should not differ for more than 10 % from unity Quality control / Startup
Startup procedure: ‣ Stability, clean air, indoor air ‣ Leakage ‣ Tape sensor ‣ Flow verification, Flow ratio ‣ Neutral density filter test ‣ → Fill in „Final inspection record“ Service & Maintainance / Startup Startup screen statuses
Communication → communication with controller - erased firmware because of forced shutdown (with bootloader 200 & 210 only) → use a programmer to upload newer bootloader - hardware problem -> check cables and controller board Instrument data → Obtain data (serial number) from the controller Storage → check CF card - CF card error → get new CF card Configuration settings → read setting from the setup file - restore from one of the older setup files Valves → check operation of the ball valve - ball valve timeout Chamber → chamber movement test - locked chamber - hardware error Pump & Flow → test if pump is working Device monitoring → Win CE operating system test Service & Maintainance / Instrument status
Normal operation
Warning ; Instrument is still performing measurements, but there is/was an issue, that needs to be checked Instrument stopped. Immediate response needed. Service & Maintainance / Status list Service & Maintainance / Tests QA/QC test results • ND test (checks optical system) – slope close to 1, insect screen • flow verification (checks if flowmeters need to be calibrated); - use good flow calibrator - be sure which flow reporting standard is used • stability test - 1 s measurement interval, 20 min duration - test is automatically performed with flow=0. Fixed flow values are used to calculate BC. - if there is increased noise → upgrade firmware to 421 & 513 → electronics problem • clean air test - 1 s measurement interval, 20 min duration - if there is increased noise → clean optical chamber → check for air-conditioning effects • filter tape – tape advance length (30 mm < TA length < 40 mm) → if wrong perform tape sensor calibration Service & Maintainance Problem solving guide
1. Check instrument status 2. Check configuration (software version, firmware version) 3. Check log file (are there any »no communication. Data missing« lines. Are the ATN0 values similar for different tape advances, are there any flow calibrations) 4. Check setup file (check the parameters – compare with the standard values) 5. Check data file • detector values: check range; is there any noise? Is it the same for all spots & channels? • flow: is it stable? (should not deviate for more than 10 mlpm), check F2/F1 ratio • Status history • BC – is there any noise in the BC measurements? Is this a noise or true measurement? • Are BCX1 and BCX2 values similar? Draw all the channels BCX1 – check if they are parallel • k values: are they in the range expected for the measured air? Service & Maintainance / FAQs
• flow calibration problem -> repeat the calibration. Be sure to use calibration pad and understand the flow reporting standard • Status 387 – Tape error (slipping filter roll) → tighten the nut on the right filter spool • Status 8192 Ext device disconected • Negative data values • Noisy data – insect screen? Maintenance: Standard operating procedures
Procedure Frequency Check the sample inlet flow Once / week Site dependent, use educated judgment! Inspect and clean the size selective inlet (if present) Once / week Site dependent, use educated judgment! Verify time and date (if not set to update Once / week automatically) Inspect and clean the insect screen assembly (if Once / month present) Site dependent, use educated judgment! Inspect and clean optical chamber Once / month Site dependent, use educated judgment! Change by-pass cartridge filter Once / month (as needed) Inspect flow divider and ball valve Once / 6 months Clean if necessary Site dependent, use educated judgment! Verify flow (flow verification, flow calibration) Once / 6 months Clean Air Test Once / 6 months Stability Test Once / 6 months Inspect the sample line tubing Once / 6 months ND filter test Once / year Lubricate optical chamber sliders Once / year Maintenance: Test criteria
Test Criteria Solution Flow verification Measured flows differ by more than 10 Calibrate flow % Use good flow calibrator Verify use of correct flow reporting standard Leakage test ζ > 10 % Lubricate optical chamber sliders, check for broken o-rings Stability test PPBC61 > 450 ng/m Clean the optical chamber (point-to-point variation of BC61 channel) Possible electronics problem Clean air test PPBC61 > 550 ng/m Clean the optical chamber (point-to-point variation of BC61 channel) Check for air-conditioning effects ND filter test Optical response slope outside 0.9 - 1.1 Clean optical chamber Service the instrument www.mageesci.com www.aerosol.si