DST ObservAir Скачать руководство пользователя страница 19

 

 

36 

ObservAir

 Operating Manual 

5.5.

 

Indoor/Outdoor monitoring guidelines 

 
The ObservAir can be operated in nearly any indoor environment without 
modification: The sensor is plugged into a power source and set to run for 
as long as needed. The magnetic cover provides good moisture and dust 
protection  for  more  demanding  operating  environments,    including 
outdoors, as long as operating limits are not exceeded and direct exposure 
to water (rain) is avoided. Exposure to direct sunlight should also be avoided 
over  extended  periods,  as  this  may  cause  overheating  of  the  internal 
components. With the magnetic cover fitted, the sensor cannot be plugged 
in to recharge, limiting the deployment time to about 24 hours.  
 

For  long-term  outdoor  deployments,  the  ObservAir  should  be 

housed in a weatherproof enclosure, such as those provided by DST. It is 
best to orient the sensor with the nozzles facing downwards to prevent the 
aspiration  of  rain  or  moisture.  In  extreme  environments  that  exceed  the 
sensor’s  operational  limits  (e.g.,  freezing  conditions),  temperature 
controlled enclosures should be used. If operating in temperatures below 
5˚C,  DST  offers  the  heated  SubZero™  case:  a  tough,  hermetically  sealed 
enclosure that is specifically designed for long winter deployments.  
 

5.6.

 

 Accurate sample flow rate measurements are critical 

 
BC concentrations are inversely proportional to the flow rate of air drawn 
through  the  aerosol  filter  (see  Section  1.1.1),  so  any  flow  measurement 
errors translate directly to the reported BC. For example, if the ObservAir’s 
flow  rate  measurements  are  10%  lower  than  the  actual  value,  BC 
concentrations  will  be  overreported  by  10%.  Given  this  proportional 
relationship,  flow  rate  measurement  drift  can  be  post-corrected.    In  the 
example above, all collected BC concentration measurements can simply 
be scaled up by 10% to compensate for the flow rate drift.  
 

When  BC  measurements  are  consistently  offset  from  those 

collected by another ObservAir or reference instrument, miscalibration of 
the flow rate sensor is almost always responsible. If BC measurements are 
proportionally lower than the reference value, then it is also possible (but 
less likely) that the ObservAir is leaking. Given these potential error modes, 
it is important to validate/calibrate the flow rate sensor output and perform 
leak checks regularly (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. 
When properly calibrated, the ObservAir’s flow rate measurements should 
be within ±2 ccm of those collected with a primary flow calibrator.  

 

 

37 

ObservAir

®

 Operating Manual 

6.

 

Troubleshooting 

 

6.1.

 

LED error codes 

The  ObservAir  constantly  runs  diagnostic  checks  to  detect  and  flag 
measurement  errors  and  warnings.  When  an  error  is  detected,  the  LED 
button flashes rapidly until the error is resolved. The color and speed of the 
flashing  LED  indicates  the  error  type,  as  shown  in  Table  10  below.  Brief 
instructions on how to resolve each error type are also provided.  
 

LED Flash Pattern 

Error 

Solution  

Slow      

Yellow 

  

High 

attenuation 

Replace filter.  

Fast      

Yellow 

  

SD card 

error 

Check that SD card is properly 

inserted. Take SD card out fully 

and re-insert into the slot.  

Very Fast   

Yellow 

   Clock error 

Reset time according to the 

instruction in Section 3.6.3. 

Slow      

Red 

 

 

LED error 

Check that filter is properly 

seated. Replace with new filter.  

Fast      

Red 

 

 

Flow rate 

error 

Check that nozzles and sample 

lines are unobstructed.  

Very Fast   

Red 

 

 

Critical 

error 

Contact DST Technical Support.  

 

Table 10. 

LED error code lookup table. 

 

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  the 
magnetic cover over the top of the sensor (Figure 14). A magnetic detector 
is located inside the sensor just below the interactive LED button, and will 
trigger a hard reset when exposed to the magnets in the cover. 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 DST Technical Support.  

 

Содержание ObservAir

Страница 1: ...rational limits and warnings 11 3 Operating Instructions 13 3 1 Hardware overview 13 3 2 Interactive LED button Sensor display and control 14 3 2 1 Sensor startup 15 3 2 2 Default LED mode Pollutant c...

Страница 2: ...pport WiFi and USB communication protocols and include a 16GB removable SD card for onboard data storage Units may also be supplemented with an LTE LoRa or SigFox communication module and a GPS unit f...

Страница 3: ...collection area is 3 mm in diameter After the first filter the air flow passes through a second reference filter assembly that is identical to the first Since the air is filtered devoid of PM the int...

Страница 4: ...plication Operate the 7 ObservAir Operating Manual ObservAir for 12 to 24 hours in an environment that is free of the analyte gas es and average the voltage differential data collected over the entire...

Страница 5: ...technical specifications are summarized in the tables below All electrochemical cells are sourced from Spec Sensors Gas measurement performance specifications are adapted from data provided by the ma...

Страница 6: ...intervals 2 3 Operational limits and warnings Environmental limits Only operate the ObservAir within the conditions listed in Table 1 Temperature and relative humidity must remain between 5 to 40 C an...

Страница 7: ...nd may result in permanent damage to the unit and or harm to the user Please contact DST Technical Support at info dstech io regarding any problems with your unit that cannot be resolved with the inst...

Страница 8: ...llutants For every new start up event a new data file is created on the SD card txt file and is assigned a filename that contains the sensor s ID number and the start up time date Section 3 5 1 3 2 2...

Страница 9: ...f 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 to confirm that it is shutting down 3 2 6 Sensor alarms and...

Страница 10: ...ront panel 19 ObservAir Operating Manual 3 5 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 c...

Страница 11: ...e ADC s raw count Full scale value is 8388607 d ATN Optical attenuation unitless e BC Black carbon in g m3 f T Temperature in C g RH Relative humidity in h FR Sample flow rate in ccm i VBAT Battery vo...

Страница 12: ...tings Figure 12 6 With the Serial Monitor configured ObservAir data is displayed in real time at the time interval set by the user Commands can also be sent to the sensor using the dialog box at the t...

Страница 13: ...8 to 1 2 Set flow rate calibration coefficient Table 7 ObservAir serial commands and descriptions 25 ObservAir Operating Manual 3 7 WiFi connection Provisioning WiFi credentials to the ObservAir allo...

Страница 14: ...1 Zero calibration of pollution sensors Each ObservAir comes with a zero calibration sheet but it is good practice to periodically verify the sensor s baseline performance especially before and after...

Страница 15: ...but clearly the calibration is only as good as the reference measurements collected 4 4 Leak check The ObservAir incorporates a monolithic design architecture that is more robust than traditional ins...

Страница 16: ...loading artifact is not static it depends on the emissions source e g biomass vs diesel atmospheric conditions seasonality and other factors Therefore filter loading correction algorithms should be c...

Страница 17: ...ing can be optimized to meet your needs For example if greater BC measurement resolution is desired at the expense of filter life the flow rate can be increased past the minimum value Conversely flow...

Страница 18: ...exhaust stacks vehicle tailpipes and other pollution sources When sampling emissions directly do not exceed the ObservAir s maximum temperature relative humidity range and pollution concentration rat...

Страница 19: ...If BC measurements are proportionally lower than the reference value then it is also possible but less likely that the ObservAir is leaking Given these potential error modes it is important to valida...

Страница 20: ...38 ObservAir Operating Manual Figure 14 Hard reset using the magnetic cover...

Отзывы: