LI-8250 Multiplexer

Central to a LI-COR long-term system is the LI-8250 Multiplexer. The LI-8250 acts as a single point of access to interact with and control a LI-COR gas analyzer and up to 36 chambers or flasks.

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Where Precise Gas Analysis Meets Patented Chamber Technology

As the access point of communication, the LI-8250 lets you control, monitor, and review measurements from each chamber. When connected with a LI-COR gas analyzer, see live flux calculations and diagnostics at your site. Connect with a third-party analyzer to provide time-synchronization for post-processing of fluxes of other gases.

The LI-8250 includes an embedded Wi-Fi server. This server allows you to connect to the Multiplexer using any Wi-Fi enabled device via browser. Add a cellular modem to receive daily summary files and remotely monitor your system—visit the site only as necessary.

LI-8250

How is the LI-8250 Multiplexer different from the LI-8150 Multiplexer?

LI-8250 Multiplexer LI-8150 Multiplexer
Rugged and fieldable Checkmark Checkmark
Third-party analyzer integration Checkmark Checkmark
Custom chamber integration Checkmark Checkmark
Flask sampling Checkmark Checkmark
SDI-12 compatible long-term chambers Checkmark
Built-in Wi-Fi connectivity* Checkmark
Real-time flux processing† Checkmark
No separate analyzer control unit required Checkmark
Maximum number of chambers 36 16

* Wi-Fi connectivity limited in some countries
† When connected to a LI-COR gas analyzer

Reaching 36 Chambers

The LI-8250 Multiplexer has 8 ports. Each multiplexer port can connect to either a chamber or an 8250-01 Extension Manifold. You can have a maximum of 4 extension manifolds connected to the LI-8250 Multiplexer.

Each extension manifold also has 8 ports that can connect to chambers. Since the extension manifold uses 1 multiplexer port, each extension manifold gains you up to 7 more chambers.

With 4 extension manifolds, you can have 32 chambers on extension manifold ports and another 4 chambers on the remaining multiplexer ports.

32 chamber soil gas flux system featuring LI-8250 Multiplexer and 8250-01 Extension Manifold

The maximum number of chambers based on the number of 8250-01 Extension Manifolds in the system

8250-01 Extension Manifolds Chambers on 8250-01 Ports Chambers on Remaining LI-8250 Ports Total Chambers
0 0 8 8
1 8 7 15
2 16 6 22
3 24 5 29
4 32 4 36

Interested in measuring trace gas evolution in flasks? The 8250-660 Flask Sampling Kit enables you to use your long-term system for flask measurements too.

LI-8250 Specifications

General

  • Dimensions: 38.5 cm L × 52 cm W × 18.5 cm H
  • Weight: 7.7 kg
  • Weatherproof Rating: Tested to IEC IP55 standard
  • Operating Range:
    • Temperature: –20 to 45 °C
    • Humidity: 0 to 95% RH, non-condensing
  • User Data Storage: 8 GB total non-volatile
  • GPS: Accuracy 2.5 m CEP
  • Coverage Area:
    • Maximum radius from LI-8250 to chambers: 15.0 m with one cable assembly or 30.0 m with an Extension Manifold and two cable assemblies.
    • Maximum diameter of measurement circle: 30.0 m with two cable assemblies or 60.0 m with two Extension Manifolds and four cable assemblies.
  • Plumbing:
    • Flow rate to/from chambers: ~2 to 3 lpm
    • Pump type: Diaphragm (pumps in the analyzers subsample air stream in the LI-8250)
  • Barometric Pressure Sensor:
    • Measurement Range: 20 to 110 kPa
    • Sensor Accuracy: ±0.4 kPa from 50 to 110 kPa
    • Resolution: 0.006 kPa

Communication

  • Seven LED Indicators: Power, Ready, Ethernet activity (3), USB activity (2)
  • Connectivity: Three Ethernet Ports, Wi-Fi (not available in some countries)
  • Wi-Fi Compatibility: 2.4 GHz, 802.11 a/b/g/n/ac
  • Connectivity Ports:
    • USB-A: One sealed and strain-relieved for connection to LI-870 CO2/H2O Analyzer
    • USB-A: Two standard, internal for mass storage (file transfer) or a country specific Wi-Fi adapter.
    • RJ-45 Ethernet: Three sealed and strain-relieved for connection to LI-COR Trace Gas Analyzers, site Ethernet network, or cellular modem. Connectors also accept standard, non-sealed RJ-45 Ethernet cables for lab use.
  • Output Port Connector: RS-422 communication plus 24 VDC power, full duplex, 115,200 baud. +24 VDC output power is current limited to ~1.8 A per output port.

Power

  • Power Requirements: 10 to 30 VDC (120 VAC and 240 VAC with optional power supply). The LI-8250 powers the 8200-104/C chambers, the 8250-01 Extension Manifold, and the LI-870 CO2/H2O Analyzer.

Table 1. Total system power requirements.

Typical Power Consumption (W)
Instrument Idle Sampling/ Moving Max/ Warm-up
LI-8250 4.8 15.6 18.2
8250-01 (each) 0.8 9.2 11.0
8200-104/C (each) 0.36 4.8 N/A
LI-870 5.0 5.0 14.0

Note: The max listed for the LI-8250 is a typical maximum, there is no additional warm-up power. Chamber power reaches 4.8 W only when opening or closing, not the entire time of sampling.

AC to DC Power Supply (8250-770)

  • Dimensions: 15 cm L × 12.5 cm W × 8.5 cm H
  • Weight: 1.3 kg
  • Weatherproof Rating: Tested to IEC IP55 standard
  • Environmental Operating Conditions: Tested to IP55 for dust and water ingress
  • Operating Temperature Range: –20 to 50 °C
  • Power Requirements: 100 to 240 VAC, 50/60 Hz, 120 VA
  • Output Voltage: 12 VDC, 6.67 A
  • Alternate Power Input: 21.9 to 26.5 VDC 80 W

Flask Sampling Kit (8250-660) Specifications

Power

  • Power Requirements: Input voltage is supplied by the LI-8250 Multiplexer or the 8250-01 Extension Manifold. When a Purge Pump is configured to an Extension Manifold, the Extension Manifold must be connected to a power supply, such as the Indoor Power Supply (8250-772), via the Alternate Power Input. See Table 2 for 8250-660 power requirements.

Table 2. 8250-660 power requirements.

Typical Power Consumption (W)
Instrument Idle Sampling/ Moving Max/ Warm-up
9982-079 Thermistor Input Module (each) 0.12 0.12 N/A
9982-077 Purge Pump (each) 5.8 5.8 7.0
Flask Sampling Kit Total (each) 5.92 5.92 7.12

Note: The power requirements for the 9982-077 Purge Pump are based on the pump being configured to run in the user interface. If the pump is not configured to run, it will use no power.

Thermistor

  • Thermistor Input Module (9982-079)
    • Operating Range: -20 to 70 °C
  • Optional Thermistor Assembly (9982-081)
    • Operating Range: -20 to 70 °C
    • Accuracy: ±0.3 °C from -20 to 70 °C

Specifications subject to change without notice.

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