Super Site LI7200 Recalibration

Software Updates

• LI-7500
  • https://www.licor.com/env/support/LI-7500RS/software.html
• LI-7200
  • https://www.licor.com/env/support/LI-7200RS/software.html

Tools required in field for instrument removal

• Large crescent wrench to remove 1 meter air intake rod
• Flat head Campbell Screwdriver to remove chamber pressure line
• possibly pliers though crescent wrench has worked fine to remove line running to air pump
• a couple of different #2 phillips (long to get started and then short for turning) to remove the phillips at the base

Lab Tools

• Medium Crescent wrench to trade outlet air tube fitting for tygon fitting
• Large Crescent wrench to put gas regulators on tanks

Lab cleanup

• polish laser glass
• check Thermocouples (T_in)

Lab Procedure

1. Power up the head and let it run 20-30 minutes
2. connect up the Nitrogen and let it run for 5-10 minutes and the instrument will stabilize
   1. put chart on CO2 umol / auto, 300 seconds range
   2. need to manually adjust flow rate during the process as pressure drops in the cylinder.
3. connect up the first standard (500ppm) and let it run 5-10 minutes and then set the point... it is taking forever to get to proper point. might need to toy with flow rate... YES, increase.
4. connect the dew point generator and after things stabilize then set the first dewpoint
5. move the settings on the dewpoint generator to the high point and then after things stabilize measure set point 2
6. connect the second standard and let it run 5-10 minutes and then set the second set point.

• And, by stabilize here it is meant: watch on the interface software chart the instrument to stabilize, rather than watching a number hop up and down.
• Flow rate should be 1-2 Liters / second.
• easiest is to use the tygon tubing connected to the output side of the air. We have connectors for that.

Extra Advice

It only takes a couple minutes to stabilize the CO2 and N, but you should power up the head and run it for 20-30 min first. The dew point can take a long time, use the graph feature to monitor. Make sure you choose a dewpoint well below the ambient temp and make sure that all the hoses and instruments are roughly the same temperature. Or else you'll get condensation and be really frustrated.

Ameriflux is now recommending that you just do a single span not the dual span, and then check with ambient. But this is up to the Jamstec folks on how to run their calibrations. I'm now using a CO2 span of 550ppm or so, and checking with an ambient of 405. I use a dewpoint of 10 or 12C for span.