Calibration Issues
CO2 and H2O Analyzers
18-6
Using the LI-6400
18
3
Wait for stability
Watch CO2R_µml and CO2S_µml (reference and sample cell CO
2
concen-
trations), and when they get as low as they will go, you are ready. (If you wish
to see this graphically, press
Plot
(
f4
) then
C
(Figure 18-3). To return to the
normal text display, press
escape
). It should take less than 2 minutes to get
reasonably stable readings.
4
If re-zeroing is necessary, press
AutoCo2
(
f1
).
If both CO
2
values are within 5 µmol mol
-1
of 0, you can skip this if you
wish
2
. If you do the press
AutoCo2
, it will take about 30 seconds to do itÕs
measurements and calculations, and establish new zeros.
When itÕs done, both the CO2R_µml and CO2S_µml values should be within
1 µmol mol
-1
of 0.
5
Soda Lime: full scrub
Desiccant: full scrub
Now we do the water zero. Since water sticks to everything, it can take many
minutes to come to a reasonably stable ÒdryÓ reading, since the chamber and
C - CO2 Ref & Smp
H - H2O Ref & Smp
R - Ref CO2 & H2O
S - Smp CO2 & H2O
<esc> - keep current
(C/H/R/S)
Plot What?
Figure 18-3. Pressing plot (f4) brings up these choices for a strip chart
display. This allows you to graphically determine if stability has been
achieved. The strip chart shown is the R choice.
2.
Note that the zero only affects absolute concentrations; the relative readings
(differentials) are taken care of by matching, described on page 4-34.
Summary of Contents for LI-6400
Page 1: ...Using the LI 6400 Portable Photosynthesis System ...
Page 15: ...Part I The Basics ...
Page 16: ......
Page 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Page 175: ...Part II Useful Details ...
Page 176: ......
Page 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Page 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Page 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Page 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Page 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Page 289: ...Part III Working With Files ...
Page 290: ......
Page 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Page 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Page 375: ...Part IV Configuration Issues ...
Page 376: ......
Page 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Page 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Page 455: ...Part V Maintenance Troubleshooting ...
Page 456: ......
Page 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Page 593: ...Part VI Programming ...
Page 594: ......
Page 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Page 846: ...Index I 16 Using the LI 6400 ...