Calibration 
 
CIRAS-2 Operator's Manual Version 2.04 
- 145 - 
Performing Calibrations 
 
Allow the CIRAS-2 to warm-up for at least 30 minutes.  From the above notes, connect up  CIRAS-2 to the 
calibration source then from the PC Windows display, select Utilities – Calibration - Start.  Next, click on 
the type of calibration (CO
2
 or H
2
O) and if you are using an external CO
2
 source, enter the concentration 
from the gas cylinder. Click OK. 
 
 
 
CIRAS-2 will now perform a zero and when the displayed concentration is steady click the corresponding 
button.  After calculating the calibration factors, the existing and new factors will be displayed.  The option 
is then given to use the new factors, retain the existing factors or return to the factory defaults. 
 
If it is decided to use the new factors then it is recommended that the calibration procedure be repeated to 
check their veracity. 
Calibration Check 
 
A calibration check feature is designed into the system to verify system calibration for both CO
2
 and H
2
O.  
The internal standard is used for the CO
2
 checking and the water vapour calibrator for the H
2
O. 
Click  on  Calibration  Check  -  Start. Connections  and  precautions  are  as  described  under  the 
corresponding calibration.