Turn the sensor head fan ON and OFF and listen to the change in ... Set flow to 500μm/s (press 2 > F2 > F > 500 > enter) and turn the fan back ON (press 2 > F1 ...
LI6400-XT Basic functionality check procedure
During warm-up 1. Check to make sure soda lime and desiccant tube chemicals are fresh and trustworthy. • Note the colour of the desiccant is blue and not pink • To perform a soda lime test, select New Msmnts (F4) and press A to display CO2R_μml • Blow a puff of air at the inlet tube on the right side of the console and watch CO2R_μml • A sharp spike of more than 2 ppm would indicate the soda lime should be changed 2. Press H to display all three temperatures (Tblock°C, Tair°C & Tleaf°C) in one row. Check if they are within a few degrees of each other. 3. Press G to display ParIn_μm and ParOut_μm. Check to see ParOut_μm respond as expected when the sensors are illuminated and darkened. 4. Press 2 and then F1 to access fan settings. Turn the sensor head fan ON and OFF and listen to the change in sound. Press O to turn off and 5 to turn on. When finished leave the fan on.
After warm-up The IRGAs should have been on for at least 10 minutes for it to sufficiently warm up
1. Check flow zero • Press B and monitor Flow_μml. • Turn the flow off (press 2 > F2 > N) and the fan off (press 2 > F1 > O). • If Flow_μml drops within 1 or 2 μmols-1 of zero, skip to section 3. If it doesn’t, refer to re-zeroing the flow meter in the next step. 2. Zeroing the flow meter • Press ESC to return to home screen. Select Calib Menu (F3) and select Flow meter zero. An automatic program will run for 10 seconds with the fan and the pump turned off. Once finished check whether ‘Flowmeter signal’ reads within 1 mV of zero. • Press OK then ESC. Return to New Msmnts (F4) 3. Set flow to 500μm/s (press 2 > F2 > F > 500 > enter) and turn the fan back ON (press 2 > F1 > 5).
4. Close the chamber and adjust the knob to make sure it is properly sealed. To check for leaks: Press A to make CO2S_μml visible. Exhale around the leaf chamber and look for any fluctuations in CO2S_μml. It should not increase by more than 1 μmol mol-1.
5. Press ESC to return to home screen.
6. Check CO2 zero – Select Calib Menu (F3) > IRGA > IRGA zero. Read prompt screens. Press Y and any key – Set Soda Lime: full scrub and Desiccant: full bypass – Monitor CO2R_μml and CO2S_μml for stability. Press Plot (F4) to view graphically. Press ESC to return. It should take about 2 minutes to reach stability – If both CO2R_μml and CO2S_μml are within 5 μmol mol-1 of zero, skip to section 11 – If not, press CO2RS→0 (F1) to re-zero. When done CO2R_μml and CO2S_μml should be within 1 μmol of zero
Are the chemicals fresh? Will cause more harm than good by re-zeroing with old chemicals.
7. Check H2O zero – Set Soda Lime: full scrub and Desiccant: full scrub – Monitor H2OR_mml and H2OS_mml, press F4 to view the graph & ESC to cancel – After 2 minutes if it is clear the values are approaching zero, skip to step 12 – Otherwise wait for about 15 minutes for stability and then press H2ORS→0 (F2)
It can take many minutes (15 mins approx.) to come to a reasonably stable dry reading. Do not zero until stable.
8. Press Quit (F5) to exit. And ESC to return to home screen.
9. Set Soda Lime : full scrub and Desiccant: full bypass
10.Check leaf temperature zero – Unplug the purple coloured temperature thermocouple. Press F4 > H. Compare Tblock_°C and Tleaf_°C. – If they differ by less than 0.1°C, reconnect the thermocouple, and skip to step 11. Else perform next step – Adjust the small screw at the underside of the sensor head until Tblock_°C and Tleaf_°C match. Reconnect the thermocouple. 11.Press ESC and return to relevant protocol sheet for further instructions.
