Observing and Recording Leaf Gas Exchange 
 
CIRAS-2 Operator's Manual Version 2.04 
- 59 - 
Observing and Recording Leaf Gas Exchange 
Checking the System with an Empty Cuvette 
 
With the cuvette closed and without a leaf inserted, you should conduct a routine test to ensure that all 
values are stable and that the desired control settings are achieved.  Stablity is easily observed by a flat 
(horizontal) profile of the colored plots as they progress in time across the display screen.  Select and 
observe only the measured parameters associated with CO
2
 and water vapor from the „Select Variables‟ 
field: Cr, Cd, Hr, Hd.   
 
Within several minutes a display similar to the one below should be observed, assuming the system has 
been  adequately  warmed  up  and  all  steps  in  Preparations  for  Use  (on  page  18)  have  been  carefully 
followed: 
 
 
 
 
Please note the following: 
  Cr (Reference CO
2
) value should be near your Setpoint value and stable (+/- 2 ppm). 
  Hr (Reference H
2
O) value should be at ambient and stable (+/- 0.2 mb). 
  Cd and Hd values should be stable at approximately 0.0 (+/- 0.5 ppm CO
2
 / 0.2 mb H
2
O). 
  Tc (Chamber Temperature) value should reflect your selected temperature value. 
  Tl (Leaf Temperature) value should be within approximately 1.5 °C of the Tc value. 
  Q (PAR) value should be near your Setpoint value (with attached LED light unit) or ambient (if no 
light unit is not used)  
  Battery voltage for both the left and right batteries should be > 13.0 V if fully charged.