Related Manuals for DST ObservAir
Summary of Contents for DST ObservAir
- Page 1 ObservAir Operating Manual Distributed Sensing Technologies Released: April 2023 Version: 2.2 © 2022 Distributed Sensing Technologies,...
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Page 2: Table Of Contents
Filter tab replacement ............19 3.3.1. Attenuation reset ............21 3.4. Battery charging ............... 21 3.4.1. Charging Outside of Enclosure ........21 3.4.2. Charging Inside Enclosure ..........21 3.5. Active Ventilation Enclosure ..........22 3.5.1. Enclosure Overview ............22 ObservAir ® Operating Manual... - Page 3 5.4. Operational settings for common applications ..... 44 5.5. Indoor/Outdoor monitoring guidelines ........ 46 5.6. Accurate sample flow rate measurements are critical... 47 Troubleshooting ............... 47 6.1. LED error codes ..............47 6.2. Unresponsive sensor ............48 ObservAir Operating Manual...
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Page 4: Introduction
Custom mounting and packaging solutions for mobile and airborne platforms are also available on request. The ObservAir is designed to be easily deployed anywhere, and trusted to deliver accurate air quality measurements reliably and conveniently. If you ObservAir ®... -
Page 5: Principle Of Operation
For most purposes, BC is functionally defined as the light-absorbing component of PM pollution. The ObservAir's micropump first draws air into the inlet and through a fibrous aerosol filter. that is mounted on black supporting material (the disposable filter tab). - Page 6 Figure 2. Schematic of the aerosol absorption photometer Optical attenuation (ATN) is defined in terms of the two light intensity measurements, as shown below. In the ObservAir, both measurements are reported as the bit count from the photodiodes’ Analog to Digital Converter (ADC), ranging from 0 to 8388607 (full scale 23-bit output).
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Page 7: Electrochemical Cells (Gaseous Pollutants)
By default, the ObservAir uses a MAC of 7.8 m /g, but this value may be adjusted following cross-calibration with a reference instrument. For the default factors specific to the ObservAir, Equation (2) simplifies to: �� Δ������ ���� ( ��... - Page 8 O from the sample. The O cell has no filter and outputs a signal that is proportional to the concentration of both O AND NO in the sample. As a result, each O cell ObservAir ® Operating Manual...
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Page 9: Environmental Compensation
As a result, traditional instruments must be housed in dedicated stations maintained at stable operating conditions, which is costly and cumbersome. In order to overcome these limitations, the ObservAir incorporates proprietary hardware and software features to minimize the sensor’s environmental dependence. These unique features enable the... -
Page 10: Black Carbon (Bc) Compensation
This software compensation centers on DSTech’s proprietary environmental training approach. Prior to delivery, all ObservAir units sample filtered air for at least 24 hours while being subjected to fluctuating environmental conditions. Using the data collected during this training period, the unique environmental dependence of each ObservAir’s absorption photometer is modeled... -
Page 11: Gas Compensation
Please contact us at info@dstech.io for more information on this procedure. 1.3. Base package contents Each ObservAir comes with the following base set of accessories and supplies: • 10 replacement filter tabs • Micro-SD card with 16 GB capacity •... -
Page 12: Technical Specifications
ObservAir data collected at a sample flow rate of 100 ccm near standard atmospheric conditions: Temperature and relative humidity (RH) ranging from 15 to 30ºC and 25 to 40%, respectively. 2.1. General specifications Table 1. ObservAir general specifications ObservAir ®... -
Page 13: Measurement Performance
2.2. Measurement performance Table 2. Measurement performance specifications ObservAir Operating Manual... -
Page 14: Operational Limits And Warnings
• Moisture/rain: The ObservAir must not be directly exposed to rain or moisture of any kind without a DSTech enclosure. When fitted with external sampling lines, these must be fitted with rain covers or water catches to ensure that water is not aspirated into the sensor. -
Page 15: Data Processing Overview
110V/60Hz and 220V/50 Hz – simply adapt to local plug style if needed. Do not use chargers rated above 2.1A or below 2.0 A. The ObservAir can also be charged from computer ports that are rated to at least 500mA. -
Page 16: Operating Instructions
Data from other sensors, such as that used for particulate matter monitoring, are not processed in any way. Data is simply logged from the third-party hardware, which often incorporates data processing procedures similar to that outlined here. 3. Operating Instructions 3.1. Hardware overview ObservAir ® Operating Manual... -
Page 17: Interactive Led Button: Sensor Display And Control
The ObservAir is shown in Figure 5 below. The sample air inlet and outlet nozzles are located on the front panel, and are denoted by arrows facing towards and away from each nozzle, respectively. The SD card slot and USB port are also located next to one another on the sensor’s front panel. -
Page 18: Sensor Startup
LED will flash the menu item color to confirm the selection. To exit the menu, press and hold the button through the entire menu selection, the LED will start breathing normally, and you can release the button. ObservAir ® Operating Manual... -
Page 19: Sensor Shutdown (Power Off)
3.2.4. Sensor shutdown (Power off) To turn off the ObservAir, hold the LED button to cycle through the menu until the first red flash and release. The sensor will flash red two more times and make a chime to confirm that it is shutting down. -
Page 20: Filter Tab Replacement
If the ObservAir displays an error, refer to Section 6 for troubleshooting instructions to diagnose and resolve the issue. 3.3. Filter tab replacement To change the filter tab, first release the thumbscrew by turning it counterclockwise for about four full turns (Figure 7). Remove the filter tab by pulling it straight out from the front of the sensor. - Page 21 (indicating an error), check that the filter tab has been inserted fully into the sensor and is properly aligned in the slot, as shown in Figure 9). If the filter is changed while the instrument is off, it will take ObservAir Operating Manual...
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Page 22: Attenuation Reset
ATN through the clean filter is therefore not equal to zero, as desired. The ObservAir automatically detects when the filter tab has been changed, measures the apparent ATN, and offsets the ATN data by this value such that ATN = 0 when the filter is clean. -
Page 23: Active Ventilation Enclosure
3.5.1. Enclosure Overview In Figure 10 below, the outdoor enclosure of the ObservAir is depicted, displaying a view from the bottom of the instrument. Key features showcased in this illustration include the 12V barrel jack power input, the... -
Page 24: Enclosure Mounting
The accompanying image to the right demonstrates the enclosure with the hardware properly secured. The ObservAir's versatile mounting system offers universal fitment, enabling users to fasten the device using screws, zip ties, or any other suitable method based on the deployment location. - Page 25 Figure 11. Enclosure Mounting Points In Figure 12 below, a deployed ObservAir sensor is illustrated, demonstrating the proper mounting orientation. The bottom side, which houses the PM sensor, RH/T sensor, and inlet/outlet vents, should be positioned facing the ground. This image also includes the optional solar panel attachment.
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Page 26: Solar Power Kit
The solar charging enclosure shares the same mounting process as the ObservAir Outdoor Enclosure, with hardware attached to the rear mounting points as detailed in 23 Figure 13 below displays the complete ObservAir system, incorporating the solar charging enclosure, mounting bracket with solar panel, and ObservAir enclosure. -
Page 27: Mounting Panels To Bracket
Figure 13. ObservAir System with Solar Kit – This illustration showcases the complete ObservAir system, highlighting the respective connections between the different components. In the image, the second unused connection is designed for use with a dual-panel system. 3.5.4. Mounting Panels to Bracket... -
Page 28: Data Collection From Onboard Sd Card
3.6. Data collection from onboard SD card While the ObservAir is operating, data is written to the onboard SD card in real time as both a primary means of data collection and a reliable physical backup when wireless data transmission protocols are implemented. - Page 29 LEDtimeout: The time duration, in minutes, before which the LED display turns off automatically. Default is 20 minutes. o. maxATN: Maximum optical attenuation (ATN). When filter loading is above this value, an alarm is triggered. Default is 80. ObservAir Operating Manual...
- Page 30 ObservAir unit. Most factors in this field are for DSTech’s internal protocols, but those pertinent to the end user are listed below: a. BC_mref, BC_bref, BC_msig, BC_bsig: Environmental compensation factors for black carbon measurement.
- Page 31 If the unit is connected to an outdoor enclosure equipped with PM, the following columns will be appended to those above: a. PM1: PM concentration in µg/m b. PM2.5: PM concentration in µg/m c. PM4: PM concentration in µg/m d. PM10: PM concentration in µg/m ObservAir Operating Manual...
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Page 32: Data File
3.6.2. Data file The ObservAir data is written in comma separated value (csv) format to a .txt file. Each line in the file represents a datalogging event, and starts with the character “$”. Values are listed in the order provided in the colNames field of the corresponding setting entry. -
Page 33: Computer (Serial Usb) Connection
3.8. Computer (serial USB) connection The ObservAir can stream data and receive commands via a USB serial connection to a computer. While any serial monitor may be used to communicate with the sensor, we recommend the free and open source Arduino Serial Monitor for the basic operations outlined in this manual. -
Page 34: Serial Data Collection
Serial data is streamed in the same format as it is saved to the SD card (Section 3.6.1). Please note that the Arduino Serial Monitor does not have data logging capability. Any serial logging software can be configured to save ObservAir data using the serial port settings in Table 5. Port ID... -
Page 35: Sensor Configuration: Serial Commands
3.8.3. Sensor configuration: Serial commands Commands can be sent over the Serial Monitor to configure the ObservAir’s various operational settings. Most serial commands share the same basic format: $cmd$val where ‘cmd’ is the name of command, and ‘val’ is the desired setting value. For example, the command ‘$setFR$100’... -
Page 36: Wifi Connection
(iOS and Android), as outlined in the Cloud Dashboard manual. Once connected, the sensor saves the WiFi credentials to memory. The sensor automatically detects and connects to saved networks. More networks can manually be added to the ObservAir’s memory using the ObservAir Desktop application or serial commands. ObservAir ®... -
Page 37: Firmware Updates
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). -
Page 38: Calibration: Gaseous Pollutants
If calibrating relative to another absorption photometer, ensure that the reference instrument is operating at a wavelength of 880 nm, like the ObservAir. Derive a linear regression between the ObservAir and reference BC data, as shown in Equation 6, and note the slope. - Page 39 Collocation should be long enough to ensure that a representative sample of gas concentration measurements is collected – typically at least 1 week is required. Compare the data collected by the ObservAir to that collected simultaneously by the reference instrument and derive a linear calibration model, as shown below.
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Page 40: Flow Rate Calibration
(weeks or months of operation) and should be re-calibrated periodically using the instructions below: 1. Turn on the ObservAir and allow it to warm-up for at least 15 minutes. 2. Connect ObservAir to a serial monitor (Section 3.8). - Page 41 This is done by collocating two ObservAir units, each operating at a different flow rate. Typically, one unit is operated at 50 ccm, while the other is operated at 100 or 125 ccm. As the two filters load unevenly, the two sensors’...
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Page 42: Best Practices
ATN of 80 for the given input conditions. ���� = (11) ���� ∙ ���� ������ FL = Filter life (days) = Average BC concentration (µg/m FR = Flow rate (ccm) 5.2. Leak check ObservAir ® Operating Manual... -
Page 43: Flow Rate Setting: Filter Life Vs. Bc Resolution
1. Replace the filter while the ObservAir is operating. 2. Plug the ObservAir’s inlet port. A simple plug may be fashioned by tying a knot in a length of sample line (soft rubber tubing). 3. Monitor the flow rate measurement using the Cloud Dashboard or serial monitor. - Page 44 BC concentration data, or (2) conducting preliminary testing with the ObservAir at a flow rate setting of 100 ccm. The logging interval is dictated by the application context and goals. For example, long-term ambient monitoring may only require hourly measurements, while mobile platforms require rapid data logging every 10 seconds or less.
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Page 45: Operational Settings For Common Applications
25/1.3 Minimum Flow Rate (ccm)*/ Maximum filter life (days)ª Table 7. ObservAir’s minimum flow rate setting and maximum filter life as a function of average BC concentration and data logging period. The ObservAir cannot provide BC concentration data with a baseline noise <... - Page 46 Table 8. General settings for several monitoring applications Ambient monitoring: When deploying the ObservAir as a static network node over long periods (weeks or months), the flow rate should be set as low as possible to maximize filter life and reduce the maintenance effort, especially when network sites are remote or numerous.
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Page 47: Indoor/Outdoor Monitoring Guidelines
ObservAir’s maximum temperature, relative humidity range, and pollution concentration ratings (Table 2). As with other instruments, the ObservAir may require that emissions from the source be diluted, cooled, and/or dried. For transient monitoring applications, such as engine testing, measurements are typically required every 2 to 10 seconds, and therefore the ObservAir’s sample flow rate must usually be... -
Page 48: Accurate Sample Flow Rate Measurements Are Critical
(see Section 4 for instructions). Since it is not typical for the ObservAir to leak or for the flow rate sensor’s output to drift significantly, these routine maintenance tasks are often neglected, and are nearly always the source of BC measurement errors when they do occur. -
Page 49: Unresponsive Sensor
6.2. Unresponsive sensor If the ObservAir becomes unresponsive, the software may have crashed and a hard reset is required. A hard reset can be triggered by swiping a magnetic over the top of the sensor in line with the interactive LED button (Figure 17). - Page 50 When a hard reset is triggered, the LED will flash green and the sensor will restart into the normal operating mode. If the sensor becomes unresponsive often or on a regular basis, please contact DSTech Technical Support. Figure 17. Hard reset using a magnet ObservAir ® Operating Manual...
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