CIRAS-3 Operation Manual V. 1.09  185  support@ppsystems.com 
 
Zero Column Assembly 
The Zero column assembly contains 3 desiccants which are used for the analyzer ZERO ensuring long 
term stability and accuracy of the CO
2
 and H
2
O gas analyzers. 
Zero Column Assembly (Part Number 10122-1) 
 
Column Identifiers 
•  H
2
O Absorber: Drierite 
•  MS: Molecular Sieve 
•  CO
2
 Absorber: Soda Lime 
One column is filled with Drierite and Molecular Sieve 
and the other with soda lime.  Drierite removes H
2
O from 
the air stream and soda lime removes CO
2
 from the air.  
During the Zero process, the Drierite adds in a small bit 
of CO
2
 and the soda lime adds a small bit of H
2
O which 
is why Molecular Sieve desiccant is required.  After 
passing Zero air through the soda lime and Drierite, the 
air finally passes through Molecular Sieve which 
absorbs any remaining traces of CO
2
 and H
2
O for very 
accurate Zero. 
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.