SECTION 4.0
CALIBRATION PROCEDURES
4.1 Routine Calibration Check
All Series 9510 Carbon Dioxide Analyzers are fully calibrated at the factory prior to shipment. Alpha
Omega Instruments CO
2
sensors feature high accuracy and excellent long term stability characteristics.
As a result, routine maintenance is kept to a minimum. As is the case with all gas analyzers, it is
advisable to periodically check the overall system calibration. The frequency of these checks is often
determined by in-house calibration protocols. If none exists, Alpha Omega Instruments Corp.
recommends that a calibration check be made on an average of once every 6 months.
4.2 Calibration Gas
The CO
2
sensor used in the Series 9510 Carbon Dioxide Analyzer has a linear output. As a result, it can
be calibrated using a single calibration gas as long as the calibration is performed accurately. The
calibration gas should contain a defined concentration of CO
2
with a balance of nitrogen (N
2
). The actual
concentration of CO
2
should be chosen based on the range of the monitor that is being calibrated. For
instance, if the monitor that is being calibrated has a range of 0-10 %, the calibration gas that you should
use should be in the range of (60% - 90%) x (full scale range), or between 6% and 9% CO
2
with a balance
gas of nitrogen.
4.3 Zero Check
The Series 9510 does not require periodic zero check.
4.4 Procedure for Checking Calibration with a Flow Through System
1.
Select a cylinder or source of calibration gas as described in Section 4.2.
2.
When selecting a pressure regulator to use with the cylinder gas, it is advisable to use a two-stage
regulator with the second stage capable of delivering a gas sample at a pressure at under 1.0
PSIG. Connect the calibration gas to the fitting on the rear of the monitor labeled “INPUT”
3.
Power up the Series 9510 Carbon Dioxide Analyzer as described in Section 3.2. and set
the calibration gas flow rate between 100 and 300 ml/min. Monitor the analyzer response to the
calibration gas, waiting until a stable reading has been established. ( minimum of 90 seconds). If
the displayed reading does not stabilize, check your plumbing for leaks or other obvious problems.
Be sure to allow the CO
2
reading to come into equilibrium before making any adjustments.
4.
The reading in the LCD will now display the CO
2
concentration of the calibration gas. If the
CO
2
value read on the LCD differs from the calibration gas, a calibration offset adjustment should
be made so that the value displayed in the LCD is identical to that of the calibration gas. If a n offset
adjustment is to be made, the instrument must be placed in the calibration mode. To do so,
simultaneously
press the front panel buttons labeled
Alarm 1, Alarm 2, and Alarm 3
. The meter
will temporarily display "CAL" and then the CO
2
value in the LCD display will appear. If the CO
2
value displayed is lower than the calibration gas value, press the up arrow to adjust the value in
the LCD upwards. Conversely, if it is higher, use the down arrow to lower the reading. When
finished, once again press
Alarm 1, Alarm 2, and Alarm 3
buttons
simultaneously
and the "CAL"
will disappear within two (2) seconds indicating the calibration sequence has been completed.
If after initiating a calibration sequence, it is decided not to make an adjustment, allow the
instrument to time out (2 minutes), or select the “A3” pushbutton.. In doing so, the previous
calibration settings will be used.
ALPHA OMEGA INSTRUMENTS CORP.
SERIES 9510 CARBON DIOXIDE ANALYZER INSTRUCTION MANUAL
18
