Introduction to the LI-8250

This section provides an overview of what's included with your LI-8250 Multiplexer as well as the software used to interact with the instrument and process data.

What's what

After you receive your LI-8250 Multiplexer, check the packing list to verify that you have received everything ordered, including:

  • LI-8250 Multiplexer (part number LI-8250)
  • Indoor AC to DC power supply (part number 8250-772)
  • Bare-leads power cable (part number 8150-706)
  • Ethernet cable (part number 616-06116)
  • Spares kit (part number 9982-072)

With each 8250-01 Extension Manifold ordered, you should have received:

  • Cable assembly (part number 9982-056)
  • Spares kit (part number 9982-072)

And with each 8200-104 Opaque Long-Term Chamber or 8200-104C Clear Long-Term Chamber ordered, you should have received:

  • Two soil collars (part number 6581-044)
  • Spares kit (part number 8100-613)
  • Replacement gasket kit (part number 8100-612)

LI-8250 Multiplexer

Part number:
LI-8250

The LI-8250 Multiplexer is an automated system for multiplexing measurements of soil gas flux.

The central role of the LI-8250 Multiplexer is to facilitate the connection of one or more gas analyzers with multiple chambers. Data from this system is useful for characterizing spatial and temporal variation of soil gas flux.

Featuring embedded flux processing software, GPS, and internal storage, the LI-8250 Multiplexer can be configured with LI-COR gas analyzers for real-time flux calculations. The LI-8250 can also be configured and time-matched with many non-LI-COR gas analyzers to measure fluxes of your particular gases of interest.

By itself, the LI-8250 Multiplexer can connect with eight chambers. Through the use of multiple 8250-01 Extension Manifolds, the maximum number of chambers can be increased to 36.

Interaction with the LI-8250 is done by connecting to the built-in web server using the browser of your SmartPhone, tablet, or computer. The web server may be reached by Ethernet connection or using the onboard Wi-Fi network.

Analyzer connection panel overview

The LI-8250 Multiplexer can connect to your site Ethernet network or cellular modem, and can integrate many types of gas analyzers.

Component Description
Power In Connects to the bare-leads power cable (8150-706) or the optional outdoor AC to DC power supply (8250-770).
Power Out Provides power to the LI-870 CO2/H2O Analyzer.
Ethernet Connects to LI-COR LI-78xx Trace Gas Analyzers, site Ethernet network, or cellular modem (RJ-45).
USB Connects to the LI-870 CO2/H2O Analyzer.
Air In Connects to the air outlet of analyzer(s).
Air Out Connects to the air inlet of analyzer(s).

Caution: The power output is 12 VDC with a center-positive pin (). The output has a 2 A maximum and is designed to only power the LI-870 CO2/H2O Analyzer. Only use the power cable supplied with the LI-870 cable assembly (part number 9982-010), and do not attempt to power any other analyzers with the LI-8250. Drawing a current in excess of 2 A will trip the self-resetting breaker. If you trip the self-resetting breaker, you will need to power the LI-8250 off and back on to reset the LI-870 power output.

Chamber connection panel overview

The LI-8250 has ports to connect with up to eight devices at a time, including the 8250-01 Extension Manifold, the 8200-104 Opaque Long-Term Chamber, the 8200-104C Clear Long-Term Chamber, and user-built custom chambers.

Component Description
Air In Connects to the air outlet of an extension manifold or chamber.
Air Out Connects to the air inlet of an extension manifold or chamber.
Port Number The designated port number for the connected device.
Power and Communication Provides power to and communication with an extension manifold or chamber (RS‑422).

Internal overview

The internal components control the flow of air between analyzers, extension manifolds, and chambers.

Figure 1‑1. Components inside the multiplexer include the pump, interior panel, port valve manifold, which controls flow to individual ports (chambers, typically), and the system valve manifold, which controls flow through the subsample loop and attached gas analyzers.
Component Description
Pump Provides a steady flow of air through the system.
Port Valve Manifold Controls the flow to and from each port.
Interior Panel See the Interior panel overview.
System Valve Manifold Controls the flow to and from the valve manifold and gas analyzers using two valves.

Interior panel overview

The interior panel provides options for mass data storage and removal, an input for powering the multiplexer indoors, and status indicators for the multiplexer.

Component Description
USB Port For connecting to an external Wi-Fi adapter or USB mass storage.
USB Activity LED indicator that provides a steady light when connected and blinks when sending/receiving communication.
Ethernet Activity LED indicator that provides a steady light when connected and blinks when sending/receiving communication.
Ready LED indicator that provides a steady light when the LI-8250 Multiplexer has finished booting up.
Power LED indicator that illuminates when the LI-8250 Multiplexer is receiving power.
Alternate Power Input For connecting to the indoor AC to DC power supply (8250-772).

What's included

Listed below are the items included with every LI-8250 Multiplexer.

Bare-leads power cable

Part number 8150-706

The bare-leads power cable is a 3 m cable with bare wire leads that allows you to connect the LI-8250 Multiplexer to a user-supplied DC power source that reliably meets your power requirements. See Power requirements and consumption to estimate your total system power requirements.

Indoor AC to DC power supply

Part number 8250-772

The indoor AC to DC power supply provides a constant 24 VDC 80 W power source using mains power. It is intended for indoor use only, such as in the lab.

Ethernet cable

Part number 616-06116

This cable has two unsealed RJ-45 connectors and is used to connect your LI-8250 Multiplexer to a computer. Because the connectors are unsealed, this cable is not intended for field use. Ethernet cables may also be included in the optional cable assemblies, but these cables are sealed and strain-relieved for field use.

Spares kit

Part number 9982-072

This kit includes additional components and spare parts for your LI-8250 Multiplexer and 8250-01 Extension Manifold.

Description Quantity Part Number
Urethane Tubing (0.9 m) 1 222-00303
Balston Disposable Air Filter 1 300-01961
Hose Barb T-Fitting 2 300-02627
Hosebarb Replacement 2 300-17717
Vinyl Cap for Quick-Connect Plug 16 620-08298
Vinyl Cap for Quick-Connect Coupler 16 620-08299
Valve Manifold Air Inlet Filter 8 9981-123

LI-8250 user interface

The LI-8250 includes a built-in web server that can be accessed using a wireless or wired connection (see Connecting to the LI-8250 Multiplexer). From the user interface, you can view and manage flux data, run diagnostics, or configure and control your long-term system. See User interface for details about how to use the user interface.

SoilFluxPro™ Software

SoilFluxPro is a free Windows- and macOS-compatible application for advanced analysis of soil flux datasets. Features include recomputation of datasets with altered parameters, graphs and charts, summary statistics, GPS data visualization with Google Earth, and more. Download SoilFluxPro from the LI-COR support site (licor.com/8250-software). Navigate to SoilFluxPro Software and find the installer for your operating system.

Optional accessories

Listed here are products that are not included with the LI-8250 Multiplexer but that are available from LI-COR for your soil gas flux system.

Outdoor AC to DC power supply

Part number 8250-770

When used with the LI-8250, the outdoor AC to DC power supply provides a constant 12 VDC 80 W power source. It is weather-resistant, O-ring sealed, and is designed for long-term outdoor deployment.

Sealed to standard Ethernet cables

Part numbers: 392-19109 or 392-19110

Sealed to standard Ethernet cables are available in lengths of 5 m (part number 392-19109) or 25 m (part number 392-19110). These cables have one sealed RJ-45 connector and one unsealed RJ-45 connector. They are used to connect the LI-8250 (sealed) to your site network (standard).

LI-190R Quantum Sensor and leveling stake

Part number 190R-8200

The LI-190R Quantum Sensor can be connected to the 8200-104/C Long-Term Chambers to measure photosynthetically active radiation at the chamber to supplement your data. The leveling stake is used to mount and level the LI-190R Quantum Sensor.

LI-200R Pyranometer and leveling stake

Part number 200R-8200

The LI-200R Pyranometer can be connected to the 8200-104/C Long-Term Chambers to measure global solar radiation at the chamber to supplement your data. The leveling stake is used to mount and level the LI-200R Pyranometer.

Stevens HydraProbe II

Part number 900-19016

A Stevens HydraProbe soil moisture, temperature, and electrical conductivity probe with SDI-12 connection cable is available to connect to the 8200-104/C Long-Term Chambers. Ancillary data from the probe is captured alongside soil gas flux data.

Sensor connector to cable with flying leads

Part number 392-18518

LI-COR offers an optional 2 m sensor connector (Turck) to cable with flying leads to connect an SDI-12 sensor to the 8200-104/C Long-Term Chambers.

Sensor T-split fitting

Part number 310-18516

The sensor T-split fitting multiplies the number of sensors that can connect to the 8200-104/C Long-Term Chambers. The sensor T-split fitting connects directly to a chamber port and serves as a junction for the connectors from two sensors, such as a light sensor and chamber thermistor or multiple SDI-12 sensors.

T-split tubing

Part number 9982-073

Pre-assembled T-split tubing is available for connecting multiple gas analyzers. The T-split tubing connects directly to the LI-8250 Multiplexer and serves as a junction for the air in and air out lines from the analyzers.

Cable assembly

Part number 9982-056

This cable assembly for the includes a 15 m RS-422 cable (part number 392-18852) and two 15 m lengths of Bev-A-Line® tubing with quick-connect fittings. This assembly provides power, communication, and gas flow between the LI-8250 Multiplexer, 8250-01 Extension Manifolds, and long-term chambers.

8250-01 Extension Manifold

Part number 8250-01

The 8250-01 Extension Manifold increases the number of chambers you can have in your long-term system by allowing up to eight chambers to share one multiplexer port.

The multiplexer can support up to four extension manifolds, bringing the maximum number of chambers to 36 (four extension manifolds connected to eight chambers and four additional chambers connected to the multiplexer). With each extension manifold you ordered, you should have received the following:

  • Cable assembly (part number 9982-056)

  • Spares kit (part number 9982-072)

Multiplexer connection panel overview

The 8250-01 Extension Manifold connects to the LI-8250 Multiplexer for power, communications, and the transfer of air.

Component Description
Power and Communication Connects to the LI-8250 Multiplexer for power and communications (RS-422).
Air In Connects to the air outlet of the LI-8250 Multiplexer.
Air Out Connects to the air inlet of the LI-8250 Multiplexer.

Chamber connection panel overview

An 8250-01 Extension Manifold connects to one port on the LI-8250 Multiplexer, and each extension manifold can connect to eight chambers.

Component Description
Air In Connects to the air outlet of a chamber.
Air Out Connects to the air inlet of a chamber.
Port Number The designated port number for the connected device.
Power and Communication Provides power to and communication with a chamber (RS‑422).

Internal overview

The internal components control the flow of air between the LI-8250 Multiplexer and chambers. The interior panel includes an input for powering the extension manifold and status indicators for the extension manifold.

Component Description
Pump Provides a steady flow of air through the system.
Valve Manifold Controls the flow to and from each chamber.
Ready LED indicator that provides a steady light when the 8250-01 Extension Manifold has finished booting up.
Power LED indicator that illuminates when the 8250-01 Extension Manifold is receiving power.
Alternate Power Input For connecting to the indoor AC to DC power supply (8250-772).

Note: The 8250-01 Extension Manifold only requires an alternate power source when using the purge pump for the Flask Sampling Kit (part number 8250-660).

Gas analyzers

The LI-8250 Multiplexer can integrate a variety of gas analyzers, including the LI-870 CO2/H2O Analyzer and LI-78xx Trace Gas Analyzers from LI-COR. Below are brief descriptions of each of these analyzers and the components necessary to connect them to the multiplexer.

LI-870 CO2/H2O Analyzer

Part number LI-870

The LI-870 CO2/H2O Analyzer is a durable, weatherized gas analyzer that provides CO2 data to the LI-8250 Multiplexer for soil CO2 flux measurement.

The LI-870 measures CO2 in air at concentrations from 0 to 20,000 ppm using non-dispersive infrared gas analysis technology. Water vapor measurements are used in corrections to report CO2 dry mole fraction with high accuracy. Power to the LI-870 is supplied from the LI-8250 Multiplexer.

LI-870 CO2/H2O Analyzer cable assembly

Part number 9982-010

Included with the LI-870 Analyzer, this cable assembly includes a 1.2 m USB-A to USB-B cable (part number 392-17654), a 1.2 m 2.5 × 5.5 mm IP68 power cable (part number 9982-008), and two lengths of Bev-A-Line® tubing with quick-connect fittings. This assembly provides power, communications, and gas flow between the LI-8250 Multiplexer and the LI-870 CO2/H2O Analyzer (see Connecting an LI-870 CO2/H2O Analyzer).

LI-78xx Trace Gas Analyzer

Part numbers:
LI-7810,
LI-7815, or
LI-7820

LI-COR Trace Gas Analyzers are high-precision, high-stability, laser-based instruments that use Optical Feedback-Cavity Enhanced Absorption Spectroscopy (OF-CEAS) to measure gas concentration in air.

LI-COR Trace Gas Analyzers provide data to the LI-8250 Multiplexer that is used to compute fully-processed fluxes in the field for gases beyond CO2, like CH4 with the LI-7810 CH4/CO2/H2O Trace Gas Analyzer or N2O with the LI-7820 N2O/H2O Trace Gas Analyzer. LI-78xx Trace Gas Analyzers are powered separately from the LI-8250 Multiplexer.

LI-78xx Trace Gas Analyzer cable assembly

Part number 9982-011

This optional cable assembly comes in a 2 m length and includes an Ethernet cable with two sealed RJ-45 connectors and Bev-a-Line® tubing with compression fittings for connecting to LI-78xx Trace Gas Analyzers (see Connecting an LI-78xx Trace Gas Analyzer).

Long-term chambers

Depending on the system you ordered, you may have one or more of the following chambers. With each chamber you ordered, you should have received the following:

  • Two soil collars (part number 6581-044)
  • Spares kit (part number 8100-613)
  • Replacement gasket kit (part number 8100-612)

8200-104 Opaque Long-Term Chamber

Part number 8200-104

The 8200-104 Opaque Long-Term Chamber has a reflective white enamel chamber bowl which rotates to and away from the soil collar. The 8200-104 is weatherized and intended to be left outdoors for extended periods of time to make automated measurements.

8200-104C Clear Long-Term Chamber

Part number 8200-104C

The 8200-104C Clear Long-Term Chamber has a clear chamber bowl which rotates to and away from the soil collar. The 8200-104C is weatherized and intended to be left outdoors for extended periods of time to make automated measurements. The clear chamber allows sunlight to reach plants in the collar, making this chamber suitable for measurement of net carbon exchange.

Soil collars

Part number 6581-044

Soil collars are a short section of pipe that provides a seal between the chamber and the soil and should be installed at the measurement site at least 6 hours prior to measurements (although 24+ hours is better). Additional collars can be purchased from LI-COR or made in a shop if you have access to suitable materials (see Making your own soil collars).

Spares kit

Part number 8100-613

This kit includes additional components and spare parts for each 8200-104/C Long-Term Chamber.

Description Quantity Part Number
Thumb nut 4 165-00140
Bumper 4 191-08069
Cable tie 9 218-08499
Urethane tubing (1.8 m) 1 222-00303
Cap plug 5 620-08297

Replacement gasket kit

Part number 8100-612

This kit, included with each 8200-104/C Long-Term Chamber, contains the components needed to replace the chamber gasket.

Description Quantity Part Number
Collar gasket 2 6581-060
Chamber gasket trim (1.8 m) 1 224-07606
Loctite adhesive 1 208-05786
6-32 x 3/8" screw 4 122-00009
4-40 x 3/8" screw 18 122-01578

Bulkhead flying lead for custom chambers

Part number 310-19090

A bulkhead flying lead is available to connect the LI-8250 Multiplexer or 8250-01 Extension Manifold to a custom chamber for communication (see Integrating a custom chamber).

Custom chamber control kit

Part number 8200-402

LI-COR offers a custom chamber control kit that can simplify integrating your custom chamber with the LI-8250 Multiplexer or 8250-01 Extension Manifold.

Description Quantity Part Number
Bulkhead flying lead for custom chambers 1 310-19090
Cable assembly 1 9982-056
Quick-connect bulkhead (female) 1 300-07126
Quick-connect bulkhead (male) 1 300-07127
Seal washer 2 167-07256

Flask Sampling Kit

Part number 8250-660

LI-COR offers a Flask Sampling Kit for measuring gas fluxes from discrete samples, such as soil samples, fruits, or small animals, in flasks.

Description Quantity Part Number
Thermistor input module 1 9982-079
Purge pump 1 9982-077
Purge pump mount 1 9982-042
Bev-A-Line® tubing (15 m) 2 8150-250
M3-0.5 x 6 mm mounting screw 10 150-14477
M3-4.5 x 14 mm standoffs 4 161-18848
Seal washer 20 167-07256
Quick-connect bulkhead (female) 8 300-07126
Quick-connect bulkhead (male) 8 300-07127
Barbed quick-connect plug (male) 16 300-07124
Barbed quick-connect plug (female) 16 300-07125
Quick-connect plug 1 300-08151
Quick-connect fitting 2 300-08251
3/32" hex wrench 1 610-04290