3.10. Firmware Updates
New versions of the ObservAir firmware are released regularly. Firmware
can be updated using a PC, as outlined in the ObservAir Desktop
Application Manual. If the instrument firmware version is 1.20.2.r6 or
greater (see settings file or online dashboard), firmware can also be
updated wirelessly using the over the air (OTA) system. For OTA updates,
the instrument must be provisioned with valid WiFi credentials and
connected to the ObservAir Cloud Dashboard. Once the sensor is
connected, contact DSTech support at info@dstech.io to schedule the OTA
firmware transfer.
3.11. External sample lines
The ObservAir can be fitted with external sample lines that extend outside
an enclosure and/or pull air directly from a flow conditioning device (e.g.
a diluter or dryer). Sample lines should be made of soft rubber tubing with
an inner diameter (ID) of 3/32 inch, such that they fit snuggly over the
nozzles (1/8-inch outer diameter). Inlet lines must be electrically
conductive to prevent particle loss. McMaster-Carr part numbers 1909T3
and 5648K23 may be used for the inlet and exhaust lines, respectively.
4. Data Calibration and Correction Procedures
4.1. Calibration: Black carbon
Each ObservAir comes from the factory with a zero-calibration sheet for
the BC sensor, but it is good practice to periodically verify the sensor’s
baseline performance, especially before and after deployments. To zero-
calibrate the BC sensor, an inline HEPA filter (collection efficiency must
be >99%) is fitted to the inlet nozzle such that no particulate matter is
sampled. DSTech provides HEPA filters for calibration, but inline HEPA
filters with barbed fittings are readily available and adapted to the
ObservAir’s inlet nozzle. Ensure that all connections are well-sealed, and
that the ObservAir freely pulls air through the filter (verify that the sensor
is pulling the flow rate set by the user).
With filter fitted, operate the sensor for at least 24 hours,
preferably at or near the intended deployment site. During zero-
calibration, hourly-average BC measurements should not deviate from 0
µg/m
3
by more than 0.1 µg/m
3
. If this condition is not met, the instrument
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