The ‘Next Generation’ Aethalometer®, Model AE33, incorporates scientific and technical advances designed to offer improved measurement performance, user features, communications and interface, and the ability to perform routine performance tests to verify correct operation. Most importantly, the new instrument incorporates the patented DualSpot™ measurement method. This provides two significant advantages: elimination of the changes in response due to ‘aerosol loading’ effects; and a real-time calculation of the ‘loading compensation’ parameter which offers insights into aerosol optical properties.
The novel Aethalometer AE33 was developed within an Eurostars project with Swiss partners Paul Scherrer Research Institute and inNET, who extensively tested the instrument in the lab and field studies.
DUALSPOT TM 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. *United States Patent 8,411,272, United States Patent 9,018,583, other patents pending
SOURCE APPORTIONMENT Discrimination of Black Carbon from fossil fuel versus biomass combustion possible with built-in analysis by a two-component model.
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 Range: <0.01 to >100 μg/m3 Black Carbon Resolution: 0.001 μg/m3 or 1 ng/m3 (user-definable display units)
SAMPLING Aerosol sample collected on Teflon-coated glass fiber filter tape. Tape advances automatically when user selectable loading threshold is reached, typically once every few hours depending on concentration and flow rate. Size selective inlets (impactor, cyclone) may be attached. • Time-base 1 second or 1 minute, post-processing to any time resolution. • Flow-rate 2 to 5 LPM provided by internal pump. Flow measured by two mass flow sensors and stabilized by closed-loop control. • Tape advances automatically on aerosol loading or at predefined times or time intervals.
OPERATOR INTERFACE Display 8.4” color touch-screen with status indicator LED’s. Interface Graphical User Interface with basic data display and control, advanced screens for detailed reporting and parameter setup. Remote management Network ready for remote management and data transfer
DATA OUTPUT & STORAGE Output • Digital data via RS-232 COM port and Ethernet 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.
QUALITY CONTROL AND ASSURANCE Automatic or manual sample flowrate calibration using an externally-attached calibrator. Verification of optical performance using a set of NIST-traceable neutral density optical filters. Automatic or manual “Dynamic Active Zero” and stability tests may be programmed to occur at specified time intervals.
PHYSICAL SPECIFICATIONS • Dimensions (HxWxD): 28 x 43 x 33 cm • Weight: 21 kg • Electrical Power supply: 100-230VAC, 50/60Hz (auto-switching) • Power consumption: 25 W average • Internal Vacuum Pump: dual diaphragm, brushless motor • Modular hardware, constructed in a fully-enclosed 19” rack mount 6U chassis, hermetically sealed Product specifications Specifications are subject to change without notice.
- Neutral Density Optical Filter validation kit (PN 7662)
- Ambient meteorological sensor, with 10-m cable (PN 5510) Aerosol Inlet Dryer including external pump (PN 5610)
- PM2.5 inlet (2.5 μm @ 5 LPM) (PN 4110)
- PM1 inlet (1 μm @ 5 LPM, 2.5 um @ 2 LPM) (PN 4114)
- Mini PM Inlet configurable: PM1, PM2.5, PM4, PM10, TSP (PN 4121)
- CO2 sensor, integrated with AE33 airflow & data acquisition (PN 5710)
- Flow Calibrator, with cable for automatic/manual use (PN 7900)
- Insect Screen Assembly with Water Trap (PN 9556)
- Tape Sensor Calibration Disc kit (PN 3410)
- Shockproof & waterproof transit case (PN 9610)
The Model AE33 Aethalometer 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.
THE DUALSPOT™ MEASUREMENT METHOD
The Model AE33 Aethalometer incorporates the patented DualSpot™ measurement method. This completely solves the loading-dependent nonlinearity which affects the data from any filter-based optical analyzer. The method explicitly does not require any knowledge or assumption about the existence, origin or magnitude of any optical nonlinearity: in fact, the calculation yields the “Loading Compensation Parameter” as an instrumental data output, which may offer insights into the origins and optical properties of the aerosol.
7-WAVELENGHT OPERATION: UV-IR, 1HZ DATA
The analysis is performed at 7 optical wavelengths spanning the range 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
An Ångström Exponent model is used in real time to calculate the fraction of BC that may be attributed to biomass combustion.
CALIBRATION AND IN-FIELD VALIDATION
The optical performance of the Model AE33 Aethalometer 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 at the instant with the original reference values. Other built-in test programs offer routine checks of stability and leakage. These features provide the Quality Assurance that is essential both for routine monitoring and research use.
USER AND COMMUNICATIONS INTERFACES
User and communications interfaces permit remote monitoring of operation; data retrieval; performance of internal tests; and reporting of ‘state‐of‐health’ parameters. Networked services offer automated status reports, issuing daily ‘Green’ reports when the instrument is functioning correctly; ‘Yellow’ reports when the instrument detects that it will need routine attention soon; and ‘Red’ reports immediately upon detecting any fault condition.
RUGGED, RELIABLE, AUTOMATIC
The Aethalometer has been developed over almost 40 years to offer rugged, reliable, and automatic operation. The Aethalometer recovers automatically from power interruptions and no operator attention is required for weeks or months, other than replacing the roll of filter tape.