LI-7000 Frequently Asked Questions
Q How do I perform an injection for small volumes of gases?
A The LI-7000 can measure small volumes of gas by passing CO2 free air into the sample (B) cell. After generating a calibration curve with known gases, the user injects the small volume samples. While the CO2 free air flows through the cell, a syringe with the small-volume of gas is injected. For a detailed application note on this, please visit: https://www.licor.com/documents/iz1drf5m77c93geim8hw.
Q What are some of the applications the LI-7000 is designed for?
A Providing inherent stability and wide operating temperature ranges, the LI-7000 can be used for a variety of applications including plant gas exchange, vertical profiling, atmospheric monitoring, pCO2 measurements and more. The user cleanable optics and software functions including curve integration and peak detection make the LI-7000 well suited for both lab and field measurements of CO2 and H2O.
Q What pumps are needed with the LI-7000?
A You will need a pump with the maximum flow of greater than 50 liters per minute. LI-COR offers a list of parts and alternative vendors that offer pumps to move air through the analyzers. Specifications for this and a list of parts and vendors can be found at: https://www.licor.com/documents/dmhq6ow23w2qgy3dsb8v.
Q How do you correct for the effects of water vapor in the air sample?
A The LI-7000 applies a band broadening correction to correct the CO2 measurement for the influence of water. An application note detailing water vapor corrections can be found at: https://www.licor.com/documents/igs56gijkc4ftks30pci.
Q What benefits does the LI-7000 have by being a differential gas analyzer?
A The LI-7000 is a differential gas analyzer, which measures the difference between the concentrations in the reference cell and the sample cell. The analyzer can resolve very small differences in the CO2 and H2O concentrations between the sample and reference gases. This is useful in applications such as soil gas exchange studies, insect, plant, or animal respiration studies, and others.
Q How often do I need to have my instrument calibrated?
A No regularly scheduled factory calibration of the LI-7000 is required. The LI-7000 offers an optical bench that can be dismantled and cleaned by the user without the need for factory calibration. User zero and span checks are suggested after cleaning the optical bench and on a monthly basis, depending on the user's preference. Water vapor span checks can be done with the help of the LI-610 Portable Dew Point Generator. Factory calibration is available based on the user's preference.