8
ObservAir
Operating Manual
proprietary environmental training approach. Prior to delivery, all ObservAir
units sample clean (‘zero’) 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
unit is modeled mathematically. The models are uploaded to each unit, and
used to correct air pollution concentration measurements in real-time. Each
ObservAir is delivered with its own unique zero-calibration sheet, as shown
in Figure 3 below. The calibration sheets show the sensor’s baseline
environmental dependence and measurement performance both before
and after compensation. The sensor also carries out regular calibration and
diagnostic checks of the underlying electronics, and includes other software
features to maintain and validate sensor performance.
Figure 3.
Each ObservAir comes with its own zero-calibration sheet
1.3.
Base package contents
Each ObservAir comes with the following base set of accessories and
supplies:
•
Magnetic cover
•
10 replacement filter tabs
•
Micro-SD card with 16 GB capacity
•
Charger (US Plug) and 3-foot (1 m) micro-USB cable
•
3-foot (1 m) length of conductive sample line
•
Zero-calibration sheet (hardcopy)
•
Quick-start guide (hardcopy)
9
ObservAir
®
Operating Manual
2.
Technical Specifications
The ObservAir’s 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 manufacturer, and where possible, DST validation of the
electrochemical cells in the ObservAir platform. All baseline measurement
noise specifications are derived from data collected while the ObservAir is
sampling clean (‘zero’) air. More information on the electrochemical cells
can be found at
www.spec-sensors.com
.
All measurement performance specifications are derived from 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
Air pollution
measurement species
Standard:
Black carbon (BC) aerosol
Optional:
CO, NO
2
, SO
2
, H
2
S, O
3
, ethanol (up to 2)
Principle of operation
Black carbon:
Filter-based light absorption (880 nm)
Gases:
Electrochemical cells
Communications
Standard:
Wi-Fi, Bluetooth, USB
Optional:
LTE, LoRa, SigFox (choose one)
Sample air flow rate
50 to 200 ccm
Sample interval
2 to 60 seconds
Power consumption
1.2 W (at 100 ccm flow rate)
Battery life
≥
24 hours (at 100 ccm flow rate)
Filter life
(BC
avg
= 1
μ
g/m
3
)
Flow rate (ccm)
50
125
200
Filter life (days)
6.3
2.5
1.6
Data storage
Removable SD card (16Gb card provided)
Operating conditions
Temperature: 5 to 40ºC; RH: 15 to 80%
Dimensions/Weight
120 x 80 x 45 mm / 600 grams
Charging
5V DC at 2.1A max (microUSB and charger provided)
Table 2.
ObservAir general specifications