Section 5. Maintenance
2
Install a 10 to 20 cm length of tubing to the air outlet.
This vent prevents ambient air from diffusing upstream into the optical cell.
Zero
Gas
Regulator
Rotameter
× 100 cc/min
5
10
20
15
25
3
When the CO
2
concentration has stabilized, click the Zero CO
2
button.
Setting the primary CO
2
span
When choosing a span gas, we recommend a gas concentration that is close to the
upper limit of what you expect to measure. For example, if you are measuring near-
ambient levels, choose a span gas that is near 400 ppm CO
2
(as opposed to 18,000
ppm). Similarly, if you are measuring concentrations near 15,000 ppm CO
2
, a span
gas with 100 ppm would not be ideal.
4
After zeroing, flow a gas with a known CO
2
concentration through the analyzer at a rate of 0.5
liters per minute.
Caution:Disable the pump to allow tank pressure to drive the flow of calibration
gases.
CO2
Span
Gas
Regulator
Rotameter
× 100 cc/min
5
10
20
15
25
5
Enter the CO
2
concentration of the span gas into the software
5-2 Using the LI-830 and LI-850 Gas Analyzers