AQ EXPERT Instruction & Operations Manual
Version 1.13
Page 34 of 63
Make sure the concentration of the calibration gas is within the range of each sensor.
Do not use gas that will over-range the sensor.
The CO span gas can be in the range of 30 - 200 PPM, 2% accuracy with balanced
nitrogen, preferably.
The NO span gas can be in the range of 10 - 200 PPM, 2% accuracy with balanced
nitrogen, required.
The NO
2
span gas can be in the range of 10 - 20 PPM, 2% accuracy with balanced
nitrogen or air.
The SO
2
span gas can be in the range of 10 - 20 PPM, 2% accuracy, with balanced
nitrogen, preferably.
The VOC (Isobutylene) span gas can be in the range of 0 - 10 PPM, 2% accuracy with
balanced air.
The CH
2
O (Formaldehyde) span gas can be in the range of 0 - 2 PPM, with balance
nitrogen, preferably.
The H
2
S span gas can be in the range of 10 - 20 PPM, 2% accuracy, with balance
nitrogen, preferably.
The CO
2
span gas can be in the range of 2500 PPM, 2% accuracy, with balance air
Make sure the concentration of the calibration gas is within the range of each
sensor. Do not use gas that could over-range the sensor.
For greatest accuracy, it is recommended that you use a span gas value close to
the gas concentration you expect to measure.
C. CALIBRATION APPARATUS
During calibration an adequate flow of span gas must be supplied without developing
excessive pressure on the sensors. A compressed cylinder of span gas must be
equipped with a primary pressure regulator. Connect the regulator of the bottled gas to
the AQ Expert “Sample In”. A simple way to feed the span gas to your monitor is by an
open T-connection that will ensure that gas is fed at ambient pressure. The regulator
valve is used to control the flow of gas to the monitor. To ensure that the span gas is fed
properly and as efficiently as possible, connect a bypass flow-meter at the outlet. Adjust
the regulator to maintain approximately 750 cc/min of flow at the outlet.
You must not feed gas to the AQ EXPERT under pressure and you must not starve the
AQ EXPERT's pump for gas. When feeding the gas, you must maintain a reasonably
constant pressure, near ambient pressure.
TO SPAN CALIBRATE THE MONITOR, IT IS BEST TO USE ONLY SINGLE GAS
MIXTURES WITH EITHER NITROGEN OR AIR BALANCE.
