CIRAS-3 Operation Manual V. 1.09  17  support@ppsystems.com 
 
Insert a fresh CO
2
 cartridge 
CO
2
 cartridges allow for accurate and precise control of CO
2
 and we highly recommend using them for 
best results.  Unscrew the CO
2
 cartridge holder and insert a new CO
2
 cartridge as shown below.  Next, 
screw the holder into the CO
2
 regulator turning clockwise until snug.  If you hear a small hiss (indicating 
the cartridge is being pierced) continue to turn the holder until snug to ensure that the cartridge is both 
pierced and sealed properly into the regulator assembly.  Each CO
2
 cartridge will last at least 24 hours 
from the time it is installed. 
 
We use 8g CO
2
 cartridges which are manufactured by a company called ISI (https://www.isi.com/).  They 
can easily be sourced from many different suppliers around the world.  If you have any questions or 
problems related to these CO
2
 cartridges please contact PP Systems. 
 
Is it possible to perform measurements under ambient conditions without using a 
CO
2
 cartridge? 
Yes and it is very easy.  To do so make sure that the CO
2
 cartridge holder is empty and that the soda lime 
is removed from the CO
2
/H
2
O control column on the CIRAS-3 console.  The empty soda lime column will 
ensure that ambient air is used for your reference air and the column will simply act as a smoothing 
volume.  Go to Settings (F2) and select “Ambient (remove chemicals)” for CO2 Reference. We just 
wanted to bring this to your attention for future use but for this tutorial we will be using a CO
2
 cartridge for 
controlling CO
2
.