Connecting an LI-870 CO2/H2O Analyzer

Part numbers: LI-8250, LI-870, and 9982-010

The components you will need to make this connection are the LI-8250 Multiplexer (part number LI-8250), the LI-870 CO2/H2O Analyzer (part number LI-870), and the LI-870 CO2/H2O Analyzer cable assembly (part number 9982-010).

The LI-870 CO2/H2O Analyzer offers precise measurements of CO2 concentration for flux measurements with the LI-8250 Multiplexer. Connection is simple, and power is supplied to the LI-870 directly from the LI-8250 Multiplexer.

A complete user manual is sent with the LI-870 CO2/H2O Analyzer, and the material can also be found at the LI-COR support site at This section demonstrates connecting the cable assembly. Instructions for configuring a measurement are detailed in An overview of configurations.

Caution: The LI-870 CO2/H2O Analyzer is water-resistant, but it is not waterproof. It should not be allowed to sit in standing water or be directly exposed to driving rain. In hot environments, the LI-870 CO2/H2O Analyzer may require a cover for shade to stay within its operating temperature range (-20 to 45 °C, without solar loading).

Making the connection

Connecting the LI-8250 Multiplexer and the LI-870 takes just a few steps.

The LI-8250 Multiplexer and the LI-870 CO2/H2O Analyzer each use metal quick-connect fittings for air tubing. A male and female connector comes factory-installed on each end of the LI-870 cable assembly.

First, connect the air tubing quick-connect fittings, male USB-B connector, and power cable connector to the LI-870.

For both ends of the power connector, note that the cable end consists of the power connector itself and an outer nut that must be threaded onto the LI-870 and multiplexer.

Complete the connection by connecting the air tubing quick-connect fittings, male USB-A connector, and power cable connector to the multiplexer.

Note: For a fully seated and sealed connection, ensure the clips above and below the USB connector have locked over the connector and the power cable is fully tightened.

Note: Only use the supplied USB-A to USB-B cable from the LI-870 cable assembly.

Warning: Only use the power cable supplied with the LI-870 cable assembly (part number 9982-010).

Powering on the LI-8250 Multiplexer will also power up the LI-870 (assuming you are properly connected). The optical bench of the LI-870 needs to warm up and achieve a steady state temperature and pressure before making measurements. This step may take up to 10 or 15 minutes, depending on ambient temperature.