One of the most frequent maintenance issues encountered at LI-COR is clogging of the 6400-01 CO2 Injector filters due to oil present in the CO2 cartridges. There are a number of brands of CO2 cartridges; some have more oil present than others. When using cartridges supplied by LI-COR, we recommend that you inspect the filter after using 25 CO2 cartridges. With other brands of cartridges (e.g. Crossman, Copperhead) you may need to inspect the filter after using a single cartridge, as they contain more oil. Replacement filters are available from LI-COR under part number 301-04472. In an emergency, you can also use a cigarette filter; remove the paper from around the filter and discard.
Figure 1 shows the location of the filter; unscrew the filter cap to access the filter. Follow these steps to verify the operation of the CO2 Injector:
1. Remove the filter and inspect; replace if contaminated with oil.
2. Inspect the O-rings, both on the CO2 piercing block, and on the back of the CO2 source mounting block, where it attaches to the LI-6400 console. Replace if damaged or contaminated with oil.
3. Install a fresh CO2 cartridge.
4. Check for flow by placing your finger over the small hole in the back of the source mounting block for about 5 seconds. Listen for a slight “pop” when you remove your finger.
5. Install the CO2 Injector on the LI-6400 console.
6. Take measurements as per usual.
7. When finished for the day, remove the CO2 Injector from the console to prevent CO2 from leaking into the system and saturating internal components.
Figure 1. 6400-01 CO2 Injector filter location.