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MRK-D-0048 V4
Aeroqual Dust Sentry / AQS User Guide
Page | 52
Figure 7-5 When using the Ozone calibrator, make sure the tee fitting is capped
Figure 7-6 When using the AirCal 1000 make sure the tee is un-capped
NO
2
calibration procedure overview
The NO
2
measurement is determined by the difference between two measurement modules; the O
x
module and the Ozone module.
The O
x
module responds towards both NO
2
and Ozone. The NO
2
concentration is determined by
difference according to Equation 1.
[NO
2
] = [O
x
]
– a[O
3
]
The NO
2
a
value is set at the Aeroqual factory and adjusts for the relative response of the O
x
module
towards ozone calibration gas.
The
a
value should be checked and adjusted as part of routine field calibration, see Figure 3b.
Note that only the
a
value is set for NO
2
, the offset should be left at 0.000 and the gain should be left
at 1.000.
Below is a brief summary of the calibration steps for the NO
2
/O
3
system. These steps must be carried
out in the order described here. A detailed step by step process is described later in this document.
NO
2
calibration steps
NOTE: Gain and value adjustments vary as follows
The Ox module gain adjustment is made during the NO2 calibration gas delivery
The NO2 a value adjustment is made during the Ozone gas delivery
The NO2 gain value is NOT adjusted as part of the calibration process
1. Deliver zero air from the AirCal 1000 (or a suitable gas dilution calibrator) to the monitor.