February 28, 2020

MAGEE SCIENTIFIC AETHALOMETER® MODEL AE33

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MAGEE SCIENTIFIC AETHALOMETER® MODEL AE33

The Magee Scientific Aethalometer ^® is the instrument most used in the world for the real-time measurement of aerosol Black Carbon. The Model AE33 is the culmination of almost 40 years of experience and development. It provides accurate data with aerosol speciation on time scales as rapid as 1 second, using our patented DualSpot™ technology and multi-wavelength optical analysis.

DUALSPOT^TM– PATENTED TECHNOLOGY

SOURCE APPORTIONMENT – BIOMASS BURNING VS FOSSIL FUEL

MULTI WAVELENGTH OPERATION

REMOTE ACCESS

RELIABLE AND HIGH QUALITY DATA

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PRODUCT INFO

The Aethalometer collects and analyzes 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.

In the new Magee Scientific Aethalometer^® Model AE33, two sample spots are collected from the same input air stream with different accumulation rates and analyzed simultaneously. The two results are combined mathematically to eliminate the “Filter Loading Effect” nonlinearity and accurately measure the aerosol concentration.

Additionally, the analysis is made at 7 optical wavelengths spanning the spectrum from 370 nm to 950 nm. Increases in optical absorption at shorter wavelengths may be interpreted in terms of the presence of so-called “Brown” carbonaceous material, usually an indicator of emissions from biomass combustion.

The Magee Scientific Aethalometer^® Model 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.

THE DUALSPOT™ MEASUREMENT METHOD

The Magee Scientific Aethalometer^® Model AE33 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-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

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 Magee Scientific Aethalometer^® Model 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 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 Magee Scientific Aethalometer^® 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.

SPECIFICATIONS

OPERATION

Supply voltage: 100-240 V~, 50/60 Hz
Max power consumption: 90 W. Typical power consumption: 25 W
Measurement wavelengths: 370, 470, 520, 590, 660, 880 and 950 nm
Air flow: set-points of 2, 3, 4 and 5 LPM

ENVIRONMENTAL OPERATING CONDITIONS

Indoor or sheltered use only: the AE33 is not weatherproof.
Altitude: up to 3000 m with an internal pump. Increased flow at very high altitudes possible with the external pump on request.
Temperature range: 10 – 40 degrees Celsius (instrument)
Relative humidity range: 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.

MECHANICAL SPECIFICATION

Chassis material: sheet metal
Dimensions: standard 19”/6U, rack mount
Weight: approx. 20 kg

CONNECTORS

Sampling air: inlet/outlet type – ¼” NTPF
Communication: 3x USB type A, 3x COM, 1x Ethernet

USER INTERFACE

8.4” SVGA display with LED backlight
Basic control: touch-screen
Optional control: standard PC keyboard and mouse via front-panel USB ports.
Red, Yellow, Green status LEDs

DOCUMENTS

Title	Type	Download
AE33 Aethalometer® spec sheet	BROCHURE SHEET	Download
AE33 Aethalometer® AE33 accesories data sheet	BROCHURE SHEET	Download
Magee Scientific 'Next Generation' Aethalometer® model AE33 - (WP13.13)	WHITEPAPER	Download

PUBLICATIONS

Title	Author	Publication	Year	Link
The “dual-spot” Aethalometer: an improved measurement of aerosol black carbon with real-time loading compensation	L. Drinovec et.al.	Atmos. Meas. Tech., 8, 1965–1979, 2015	2015	Download
Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements	I. Ježek et.al.	Atmos. Meas. Tech., 8, 43–55, 2015	2015	Download
The filter loading effect by ambient aerosols in filter absorption photometers depends on the mixing state of the sampled particles	L. Drinovec et.al.	Atmos. Meas. Tech., 10, 1043–1059, 2017	2017	Link
Evaluation of the absorption Ångström exponents for traffic and wood burning in the Aethalometer based source apportionment using radiocarbon measurements of ambient aerosol	P. Zotter et.al.	Atmos. Chem. Phys., 17, 4229–4249, 2017	2017	Link
The determination of highly time-resolved and source-separated black carbon emission rates using radon as a tracer of atmospheric dynamics	A. Gregorič et.al.	Atmos. Chem. Phys., 20, 14139–14162, 2020	2020	Download

VIDEO

Magee Scientific Aethalometer® Model AE33 – Stability and Clean air tests

Magee Scientific Aethalometer® Model AE33 – Flow verification procedure

Magee Scientific Aethalometer® Model AE33 – Neutral Density Optical validation procedure

Magee Scientific Aethalometer® Model AE33 – Leakage test

Magee Scientific Aethalometer® Model AE33 – Flow calibration procedure

Magee Scientific Aethalometer® Model AE33 – Installation of a new fiter tape roll

Magee Scientific Aethalometer® Model AE33 – Chamber Sliders greasing

Magee Scientific Aethalometer® Model AE33 – Cleaning the optical Chamber

Magee Scientific Aethalometer® Model AE33 – Installation of a new cartridge filter

Magee Scientific Aethalometer® Model AE33 – Field Installation Retrofit of Tape Drive Grip Spring

Dr. Tony Hansen (Magee Scientific Co.) about Black Carbon and the Magee Scientific Aethalometer®

ACCESSORIES

Magee Scientific can provide Aethalometer accessories and routine supplies such as those shown below. Please inquire with our sales team about your specific needs.

BGI TETRACAL® AIR FLOW CALIBRATOR

The BGI ‘TetraCal’® is a simple-to-use, NIST-traceable Standard for volumetric airflow, barometric pressure, and ambient temperature. The TetraCal is a venturi-based system with built-in compensation for changes in ambient temperature and pressure. The TetraCal® may be directly connected to the Aethalometer model AE33 for air flow calibration.

Specification sheet

SAMPLE STREAM DRYER

Drying the aerosol sample stream is highly recommended to provide accurate measurement data and protect the water condensation equipment.

In hot, humid locations, the water vapor content of the ambient sample air may be considerable. This can lead to inaccuracies in the BC measurement – but, more seriously, there is the possibility of water condensation inside the instrument, which can lead to permanent damage. This issue is solved by the use of our Sample Stream Dryer.

The interaction of water with aerosol species changes their physical properties. Consequently, the World Meteorological Organization has recommended that all aerosol measurements should be performed under conditions where the Relative Humidity is 40% or lower (WMO/GAW 2003; Wiedensohler, 2014).

Many stations in hot, humid locations have air-conditioned interiors. If the indoor air-conditioning temperature T_a is comparable to or lower than the dewpoint (condensation temperature) T_d of the outside ambient air, water will condense in the tubing and inside the instrument. This will not only completely invalidate the data but can also cause permanent damage to the instrument.

The Magee Scientific Sample Stream Dryer removes water vapor from the inlet flow using a semi-permeable Nafion membrane. This membrane selectively absorbs water vapor molecules from the air stream and passes them to a space on the other side of the membrane, maintained at low absolute pressure using a vacuum pump.

The Magee Scientific Sample Stream Dryer can reduce the dew point temperature by up to 14 degrees Celsius at a flow rate of 5 LPM. The equipment is self-contained, automatic, and includes a display screen that shows the input and output hygrometric properties. A data cable can connect to the Model AE33 Aethalometer to incorporate the temperature and humidity data into the Aethalometer’s data files.

The Magee Scientific Sample Stream Dryer can remove water vapor from the inlet stream to an aerosol instrument, not just an Aethalometer.

NEUTRAL DENSITY OPTICAL VALIDATION KIT

The Neutral Density Optical Filter Kit provides validation of the reproducibility of the photometric detectors.

The optical performance of the Magee Scientific Aethalometer^®Model AE33 may be validated in the field by the ‘Neutral Density Optical Filter Kit,’ consisting of four precision optical elements containing precision glass whose absorbance is traceable to primary photometric standards maintained by national organizations such as NIST (USA), NPL (UK), BIPM (EU), etc. Software routines measure the optical intensities at all wavelengths and compare the analysis during the test with the original reference values. This validates the reproducibility of the Aethalometer’s fundamental measurement of optical Attenuation.

WEATHER STATION SENSORS

Our new family of Weather station sensors for measurements of Air temperature, Pressure, Relative/Absolute humidity, Wind speed, and Wind direction consists of:

1. The GMX300 Ambient Meteorological Sensor is a combined instrument mounted inside three doubled louvered, naturally aspirated radiation shields with no moving parts. It measures air temperature, humidity, and pressure.

2.The GMX200 is a Wind speed and direction ultrasonic sensor, and with an addition of an electronic compass, it provides apparent wind measurements.

3.The GMX500 is a compact weather station (with temperature, pressure, humidity, wind speed, and wind direction sensors).

For more information, please refer to the below brochure:

Magee_Scientific_Weather_station_sensor_brochure_sheet_A4_v1

IMPORTANT: Full operation of these sensors will be enabled with the new AE33 SW update scheduled no later than 1st March 2021.

FILTER TAPE

The Magee Scientific Aethalometer^® Model AE33 collects its samples on a proprietary filter tape made of glass fibers coated with PTFE/PET and supported on a mechanical backing for transport in the instrument. When the spot reaches a pre-set loading density, the tape is advanced to create a new spot. Each roll of tape is 10 m. in length and will last from a few weeks to a few months, depending on the average concentration of BC in the sampled atmosphere and the chosen operational flow rate.

SIZE-SELECTIVE INLETS

Ambient atmospheres include suspended particles of a large aerodynamic size such as pollen, dust, etc. These particles are not strongly optically absorbing and therefore do not interfere with the Aethalometer® analysis; however, a deposit of dust in the internal optics will degrade performance after lengthy use. To exclude large particles and provide analysis of a known respirable size fraction, we recommend using size-selective inlets designed to exclude particles of aerodynamic size greater than a specified cut point at a specified sample air flow rate. We offer the ‘Sharp-Cut Cyclones’ designed by BGI (USA) and now manufactured by Mesa Labs (USA). These inlets are usually attached directly to the sample inlet tube at the entry point but may also be installed in-line closer to the Aethalometer.

PM2.5 Inlet
BGI model SCC-1.828. Provides a cut point of 2.5µm at a sample flow rate of 5 LPM.

PM1/2.5 Inlet
BGI model SCC-1.197. Provides a cut point of 2.5µm at a sample flow rate of 2 LPM or 1µm at a sample flow rate of 5 LPM.

PM1 Inlet
BGI model SCC-0.732. Provides a cut point of 1µm at a sample flow rate of 2 LPM.

BGI ‘Mini-PM’ Inlet Kit
The BGI ‘Mini-PM’ Inlet Kit offers impaction jet inserts to provide size-selective capabilities of TSP, PM-4, PM-2.5, and PM-1 when operated at a flow rate of 5 LPM.

TRANSIT CASE

For situations where the Aethalometer® must be shipped or transported frequently, we recommend the use of Pelican® transit cases. These provide internal padding, a sturdy waterproof exterior, and an integrated retractable handle and roller wheels.

EXTERNAL HIGH ALTITUDE (HA) AIR PUMP

The air pump inside the Magee Scientific Aethalometer® can supply a constant sample flow rate of 5 LMP up to
approx. 3000 m a.s.l., when the sample flow rate (reported at standard conditions) will slowly decrease. To extend the operating range of the Magee Scientific Aethalometer® up to 5000 m a.s.l. your
Aethalometer can now be connected to an external HA air pump.

Magee_Scientific_External HA air pump_brochure sheet

GENERAL QUESTIONS ABOUT THE AETHALOMETER

WHAT IS BLACK CARBON? WHY SHOULD WE MEASURE IT?

Black Carbon is a primary pollutant produced by the incomplete combustion of fuel. Its association with toxic and carcinogenic compounds makes it the Number-1 pollutant species most associated with adverse health effects. Its absorption of light makes it the Number-2 climate forcing agent, second only to CO2. Unlike CO2, whose emissions are directly related to the carbon content of the fuel, the emission of BC can differ by orders of magnitude from one combustion source to another. Consequently, the emission of BC cannot be predicted and has to be measured.

HOW DOES THE AETHALOMETER WORK?

The Aethalometer collects aerosol particles on the spot on a filter tape. The spot is illuminated from one side, and the transmitted light is measured on the other side. A blank, un-loaded portion of the filter is used as a reference. The ‘optical attenuation,’ “ATN,” is a measure of light absorption and is directly proportional to the density of absorbing material on the spot. The rate at which ATN increases is proportional to the rate of accumulation of absorbing material. Knowing the sample air flow rate, the concentration in the air stream is calculated. This analysis is performed at multiple optical wavelengths since some aerosol species may have enhanced optical absorption at shorter wavelengths.

HOW DOES THE AETHALOMETER MEASURE ONLY BC, WHILE THE AMBIENT AIR IS A MIXTURE OF MANY POLLUTANTS SUCH AS GHGS, SULFATES, NITRATES, CO2, ETC.?

The Aethalometer collects aerosols on a filter tape – but gases pass through it. Aerosol “Black Carbon” is the only species with a very strong optical absorption at 880 nm (infra-red). Some compounds of organic aerosols – such as ‘brown Carbon’ and biomass smoke – may absorb more strongly at shorter wavelengths. The Aethalometer analyzes at 7 wavelengths and can discriminate “diesel” emissions from “wood smoke.”

WHY DON’T WE NEED TO CALIBRATE THE LIGHT SOURCE INTENSITY?

The Aethalometer measures the Attenuation of the light transmitted through the sample-collecting spot relative to the intensity of light transmitted through a blank portion of the tape acting as a Reference. This ratio is independent of .the absolute intensity of the source. Therefore, the optical source intensity changes are irrelevant, and the source intensity never needs to be adjusted or calibrated.

DOES THE LIGHT SOURCE INTENSITY EVER FAIL?

Even if the output intensity of the light source changes, the ATN measurement is not affected since it is the ratio of two signals. The optical source in the Aethalometer is an array of LED chips operated at much less than their maximum rated power. Consequently, these LED sources are expected to last almost indefinitely.

The project of developing Magee Scientific Aethalometer^® model AE33 was awarded as a Success story on the Eurostars joint programme webpage. Please check this link for the details.

MAGEE SCIENTIFIC AETHALOMETER® MODEL AE33

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