6 – Calibration
MultiExact Gas Analyser
6
CALIBRATION
CAUTION
During calibration of O
2
purity, O
2
control, 0-10ppm CO, 0-10ppm CO
2
,
0-500ppm CO
2
, 0-20ppm N
2
O or 0-50ppm CH
4
measurements it is good
practice to perform a low (Lo) calibration followed by a high (Hi) calibration.
However, a single point calibration is often sufficient (see Appendix A10).
CAUTION
During calibration of TCD measurements it is good practice to perform a low
(Lo) calibration followed by a high (Hi) calibration.
CAUTION
During calibration of O
2
Trace measurements a regular low point calibration
can be performed with less frequent high (air point) calibrations
(see Appendix A10). If both high and low calibrations are being carried out
then it is important that the high calibration is carried out first.
6.1
Manual calibration
☞
The required frequency of calibration depends on the reliance that you place
upon the accuracy and consistency of the measurements made by the
analyser. Adjust the frequency according to your requirements and the drift
characteristics of your analyser (see Appendix A9 and A10).
☞
You can carry out a manual calibration at any time unless an automatic
validation/calibration is in progress.
☞
If the auto validation/calibration option is installed, the gas control relays
(Section 5.2.5) will select the correct gas once the manual calibration screen
is shown (Figure 73). Sample gas will be reselected once the screen is exited.
You
must
manually calibrate the analyser as part of the initial set up, and whenever
ambient conditions have changed.
If the analyser is configured for automatic validation/calibration (see Section 6.2):
•
We recommend that you manually calibrate the analyser regularly during normal
operation (see Appendix A10), and that you keep a record of the calibration errors.
Use the errors to adjust the required calibration frequency.
Manually calibrate the analyser as follows:
1.
Ensure that your equipment is configured to correctly route your calibration gas
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