Aeroqual AQM60, User Manual, Page: 32 / 83

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Aeroqual AQM60 User Guide
3. Some gases (eg ammonia, ethanol (see permapure website for more details)) may be
removed from the calibration gas stream by the humidifier. In this case the humidifier must
not be used to calibrate these gases. Calibrate with dry gas.
4. If the dew point at your location is normally less than - 5
o
C then you should calibrate with
only 15ml of water in the humidifier which will produce a suitable water vapour concentration
in the span gas.
5. Over time the nafion tube can become contaminated and start to scrub gases such as ozone
and NO2. You should change your nafion every 2 years.
4.3. Zero Calibration and Check
Acceptable zero baseline readings for gas sensors:
If the baseline reading is outside the acceptable range, follow the instructions below explaining how to
perform a zero calibration.
4.3.1. Automatic Zero
The Gas Treatment Module contains a zero air scrubber which can be programmed to automatically turn on
to periodically establish the zero of the instrument. The auto zero check and calibration routines turn on the
gas treatment module for
30 minutes . The interval between zero air checks can be set by the user between
1 and 255 hours.
Please Note the difference between Zero Calibration and Zero Reading

Zero Calibration adjusts the OFFSET value. The change is logged in the EVENTLOG file on the SD
card.

Zero Reading does not adjust the OFFSET value.
Note 1: The Zero Calibration optio
n can be found under “Operations” in the PC software
Note 2: The Zero Reading option can be found under “Tools” in the PC software
4.3.2. Manual Zero
Using GTM
The zero air scrubber in the Gas Treatment Module can also be used to carry out a manual zero calibration.
Before doing this you should check that the media are in good condition or if possible replace with fresh
media.
1.
Turn on “Zero Reading”
2. Allow the AQM to sample until stable readings are obtained (about 30 - 60 minutes)
Sensor Acceptable Zero Reading / ppm
O3 0 +/- 0.005
NO2, NOx 0 +/- 0.01
CO 0 +/- 0.1
SO2, H2S 0 +/- 0.03
VOC 0 +/- 0.1
NMHC 0 +/- 0.1
PID 0 +/- 0.03
CO2 0 +/- 10