CIRAS-3 Operation Manual V. 1.09
195
PLC3 leaf cuvette. As described earlier, PLC3 leaks are normally associated with the leaf cuvette
gaskets. To isolate the leak, take a small piece of tubing and gently breathe around the gaskets and
monitor the CO2d on the CIRAS-3 console. If you see a spike or increase in CO2d you have found the
leak. Replace the gaskets (see
on page 193. Also, you should check to make sure
that the head is closing and sealing properly. If the head is not sealing properly, you may need to adjust
the tension on the head. Refer to
PLC3 Leaf Cuvette Head Adjustment
on page 195.
If you observe a fluctuating CO2d value that is also > 1.0 µmol mol
-1
with the leaf cuvette simulator
connected, the leak is likely associated with the CIRAS-3 console. Normally leaks associated with the
console can be found around absorber columns especially after a recent change in chemicals. Gently
blow around the absorber columns and the H2O equilibrator to isolate leaks.
PLC3 Leaf Cuvette Head Adjustment
If the leaf cuvette head is not closing properly, a minor adjustment can be made using the adjustment
screw located below the cuvette open/close lever as shown below.
For older leaf cuvettes use a small hex wrench to adjust the screw tension if needed to accommodate
leaves of varying thicknesses. Turn the screw counter-clockwise to tighten and clockwise to loosen the
tension. Normally no more than ¼ turn in either direction is needed. For newer leaf cuvettes starting in
late 2015 we replaced the hex screw with a thumb screw making it easier to adjust with your fingers. The
goal is to establish a good seal without causing extreme pressure on the leaf or allowing ambient air to
leak around the foam gaskets. Certain leaf types are inherently difficult to seal in the PLC3 cuvette: e.g.
succulent plants, cacti, leaves with large midrib veins, woody shoots, presence of leaf exudates. The
PLC3 cuvette is designed specifically to accommodate planar leaf laminae <3 mm in thickness.
Cuvette head
adjustment
screw
