CIRAS-3 Operation Manual V. 1.09  186  support@ppsystems.com 
 
CO
2
 & H
2
O Control Column 
The CO
2
 & H
2
O Control column assembly contains 2 desiccants which are used for controlling CO
2
 and 
H
2
O.  It also includes a water vapor equilibrator. 
2
2
O Control Column Assembly (Part Number 10121-1) 
 
Column Identifiers 
•  H
2
O Absorber: Drierite 
•  CO
2
 Absorber: Soda Lime 
One column is filled with Drierite (for control of 
H
2
O) and one with soda lime (for CO
2
 control).  
Drierite removes H
2
O from the air stream and 
soda lime removes CO
2
 from the air to achieve 
levels requested by the user. 
This assembly also includes a water vapor 
equilibrator containing NAFION
®
 tubing which 
should not require replacement and is used to 
equilibrate the humidity with the ambient. 
ALWAYS change self-indicating desiccants when 
the column is approximately 50% exhausted.  If 
using non-indicating desiccants, we recommend 
changing them out prior to each measurement 
campaign to play it safe.