Dualspot patented automatic compensation for filter loading effect
Sample collection and analysis is performed on two filter spots simultaneously at different flow rates. Mathematical combination of the data eliminates the filter loading effect and provides continuously corrected data in real time with no discontinuities at filter advances.
This compensation depends critically on the aerosol composition and properties. It must be determined in real time from the measurement data, as it cannot be predicted in advance.
The parameters derived from this analysis also offer additional insights into aerosol composition and aging.
7-Wavelength Operation
UV-IR, 1Hz Data
The analysis is performed at 7 optical wavelengths spanning from the near-infrared (950 nm) to the near-ultraviolet (370 nm). The sequencing of illumination and analysis is performed on a 1-Hz timebase. This yields the complete spectrum of aerosol optical absorption with one data line every second.
Real-time source apportionment
The Aethalometer model, as described by Sandradevi et al. (2007), is employed to estimate the real-time contribution of black carbon (BC) from biomass combustion. This model distinguishes between BC emitted from biomass burning and that from fossil fuel sources, such as traffic emissions. Identifying the dominant source of black carbon is crucial for developing targeted air quality management strategies, as the health impacts, atmospheric behaviour, and policy responses differ significantly between biomass burning and traffic-related pollution.
Calibration and in-field validation
The optical performance of the Aethalometer AE33 may be validated by the Neutral Density Optical Filter Kit, consisting of four precision optical elements whose absorbance is traceable to fundamental standards. Software routines measure the optical intensities at all wavelengths and compare the analysis instantly with the original reference values. Other built-in test programs offer routine checks of stability and leakage. These features provide Quality Assurance that is essential both for routine monitoring and research use.
User and communication interfaces
The user and communications interfaces of the instrument enable comprehensive remote access, allowing for real-time monitoring of operational status, automated data retrieval, execution of internal diagnostic tests, and reporting of key state-of-health parameters. These capabilities are essential for ensuring continuous, high-quality data collection, minimizing downtime, and supporting timely maintenance interventions – especially in long-term air quality monitoring networks or remote deployments.
Rugged, reliable, automatic
The Aethalometer AE33 has been developed over almost 40 years to offer rugged, reliable, and automatic operation. The AE33 recovers automatically from power interruptions and no operator attention is required for weeks or months, other than replacing the roll of filter tape.
The Aethalometer AE33 has been developed with input from the research and monitoring communities, and is designed for reliable operation under all conditions ranging from state‐of‐the‐art research to routine air quality monitoring.
Integrates with TCA08 for OC/EC analysis
AE33 can be combined with Total Carbon Analyser TCA08 to Carbonaceous Aerosol Speciation System CASS: a revolutionary OC/EC analyser that measures:
- Total Carbon Content (TC)
- Elemental Carbon content (EC)
- Organic Carbon content (OC)
- Black Carbon content (BC)
Furthermore, using the advanced TC/BC(λ) method CASS can be used to monitor a complete fingerprint of carbonaceous aerosols, including primary and secondary organic aerosols.
Data sheets and specifications are subject to change, and Enviro Technology cannot be held responsible for inaccuracies in manufacturer-issued data sheets. To confirm specifications and obtain the latest issue of the data sheet, please contact us.
Measurement Principle
The Aethalometer collects and analyses aerosol particles continuously. The aerosol-laden air stream is drawn through a spot on a filter tape at a measured flow rate. Simultaneously, the tape is illuminated by light: sensitive detectors measure the intensities of light transmitted through an un-exposed portion of the tape, acting as a reference; versus the collecting spot.
As optically absorbing material accumulates on the spot, the intensity of light transmitted through it gradually decreases. The decrease in light intensity from one measurement to the next is interpreted as an increase in collected material. This increased amount is divided by the known air-flow volume to calculate the concentration.
The real-time analysis is performed at 7 optical wavelengths from the near-ultraviolet (370 nm) to the near-infrared (950 nm), which enables source apportionment – see below – to separate traffic or diesel exhaust from biomass burning (woodsmoke, forest fires, cook stoves…), and brown carbon calculations
Specification
- Measurement performance: 7-Wavelength Operation
- 370, 470, 520, 570, 630, 880, 950 nm characterisation of light-absorbing aerosols.
- Time base: 1 second or 1 minute, post-processing to any time resolution
- Sensitivity: Proportional to time base and sample flow rate settings: approximately 0.03 μg/m3 @ 1 min, 5 LPM.
- Detection: Detection Limit (1 hour): <0.005 μg/m3 black carbon
- Range: <0.01 to >100 μg/m3
- Resolution: 0.001 μg/m3 or 1 ng/m3
- Dualspot Technology: Simultaneous analysis of light absorption by aerosol deposits collected on 2 spots in parallel at different loading rates. Mathematical combination of data yields black carbon result independent of spot loading effects and provides additional information about aerosol composition.
- Source apportionment: Discrimination of black carbon from fossil fuel versus biomass combustion is possible with built-in analysis by a two-component model
- Quality control and assurance: Automatic or manual sample flow rate calibration using an externally attached calibrator. Verification of optical performance using a set of neutral density optical filters. Automatic or manual Dynamic Active Zero and stability tests may be programmed to occur at specified time intervals.
User interface
- Display: 8.4” color touch-screen with basic data display and control, advanced screens for detailed reporting and parameter setup.
- LED status indicators: Red, Yellow, Green.
- Remote management: network ready for remote management and data transfer.
- Optional control: standard PC keyboard and mouse via front-panel USB ports.
Installation requirements
- Temperature: 10°C – 40°C
- humidity: 5% – 95% (non-condensing). Note that it is essential to prevent condensation of humid outdoor sample air if the instrument is located in a chilled (air-conditioned) environment.
- Indoor or sheltered use
- Operating altitude: Sea Level to 3000 m (Operating range can be extended to 5000 m a.s.l. with an external air pump – optional accessory)
- Relative humidity range: non-condensing.
Storage and Data Output
Storage: Data are written to internal memory once every time base period. Stored data may be transferred over a network or to a manually inserted USB drive.
Data Output: Digital data via RS-232 COM port and Ethernet
Analog output via AOM module
Physical specifications
- Dimensions (HxWxD): 28 x 43 x 33 cm
- Weight: 21 kg
- Electrical Power supply: – AC: 100-230VAC, 50/60Hz (auto-switching)
- Power consumption: 25 W average, 90 W maximum
- Internal Vacuum Pump: dual diaphragm, brushless motor
- Sampling air connectors: inlet/outlet type – ¼” NTPF
- Communication: 3x USB type A, 3x COM, 1x Ethernet
- Modular hardware, constructed in a fully enclosed 19” rack mount 6U chassis, sheet metal, hermetically sealed
