Solving An ‘Oily’ Problem

With the LI-6400XT Portable Photosynthesis System

The 6400-01 CO₂ Injector for the LI-6400/LI-6400XT requires the use of pure CO₂ cartridges to mix with CO₂-free air provided by the scrubbing action of the soda lime column.

We strongly recommend the use of cartridges purchased from LI-COR, as they combine high purity CO₂ with very low oil content.

We recognize that LI-COR cartridges are not always available due to international shipping restrictions or other reasons. In this case, other CO₂ cartridges can be used, provided precautionary steps are taken. The oil content of cartridges typically found at sporting goods stores is very high, which may be beneficial for the sporting equipment, but will damage the LI-6400XT. The filter in the external source assembly should be checked each time a sporting goods grade cartridge is used, and may need to be replaced after each cartridge is exhausted.

Food grade cartridges are commonly used in seltzer bottles and typically contain lower oil content than sporting goods grade cartridges. These cartridges commonly come in 8, 12, and 16 gram sizes. The 16 gram cartridge is too long and cannot be used. The 8 gram and 12 gram cylinders can be used, although 8-gram cartridges’ length must be artificially modified to hold the cylinder tight against the piercing pin. Inserting a few small coins into the CO₂ cylinder holder between the top of the 8-gram cartridge and cover will usually suffice to keep the cartridge tight against the piercing pin (see diagram at right). Again, the filter should be checked after each cartridge is exhausted, and should be changed as frequently as needed.