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

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.

• Magee_Scientific_Sample_Inlet_Dryer_brochure_sheet_A4
• Magee_Scientific_ Aethalometer_AE33_Sample_Inlet_Dryer_installation

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.

• Magee_Scientific_Aethalometer_AE33_ND_Optical_Validation_Kit
• Magee_Scientific_Aethalometer_AE33_accesories_brochure_sheet_A4

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.

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.

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.

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.

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