CIRAS-3 Operation Manual V. 1.09  201  support@ppsystems.com 
 
Replacement of PLC3 Glass Window (For Use with CFM-3) 
For most leaf gas exchange measurements a Calflex window is used with the PLC3 Universal Leaf 
Cuvette. However, for measurement of chlorophyll fluorescence using the CFM-3 the Calflex window 
must be replaced with a plain glass window.  When the CFM-3 is purchased with the CIRAS-3 the glass 
window is already fitted to the PLC3 Universal Leaf Cuvette.   
To remove the Calflex window plate 
remove the four Philips type screws 
and replace with the plain glass 
window plate as shown here.  To 
ensure an air-tight seal, we 
recommend putting a slight smear of 
silicone grease under the head plate 
prior to fitting it to the leaf cuvette 
head. 
Check to make sure that the letter 
“P” is etched in the lower left hand 
corner prior to measurement of 
chlorophyll fluorescence. 
After replacement of the window, we suggest that you perform a simple leak test to ensure that the 
system is air tight as follows: 
•  Set CO2r to 0 and H2Or to 100%. 
•  Close the leaf cuvette head with no leaf present. 
Monitor the CO2r, CO2d and H2Od.  After a couple of minutes, the CO2r should be close to 0 (± 1 µmol 
mol
-1
), CO2d should read approximately 0 (± 1 µmol mol
-1
) and H2Od should also read approximately 0 (± 
0.5 mb).