Multiple Chambers for Long-Term, Unattended Measurements

The LI-8150 Multiplexer greatly expands the capability of the LI-8100 and provides a simple solution that satisfies both temporal and spatial resolution requirements for monitoring CO2 flux. Designed exclusively for use with the LI-8100, the LI-8150 allows up to 16 chambers to be connected to provide adequate spatial coverage. The system's automation enables long-term, unattended measurement of diel and seasonal flux patterns.

• Connect up to 16 Long-Term Chambers

• 30 m (98.4 ft) diameter coverage

• Easy connection to the LI-8100 Analyzer Control Unit (ACU)

• Single gas analyzer in the LI-8100 prevents measurement bias

• Conduct vertical atmospheric CO2 profile measurements

LI-8150 Demonstration video

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Managing Spatial and Temporal Variability

Because of the inherent variability of soils, conducting measurements at multiple locations is often necessary to obtain a reliable mean soil CO2 flux value. For example, a relatively uniform site with a coefficient of variation (CV) of 10% may require approximately 15 flux measurements at different locations to obtain a mean value with a measurement uncertainty of about 5%.

In addition to spatial heterogeneity, soils also exhibit both diel and seasonal patterns of variation in CO2 evolution due to changes in soil water content, temperature, carbon resources, and other factors. To accurately obtain site CO2 fluxes, measurements with sufficient temporal and spatial resolution are required.

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Modular Construction

The LI-8150 easily connects to the LI-8100 Analyzer Control Unit and allows the researcher to choose an optimum number of chambers with the flexibility of adding more chambers as needed. An 8-port LI-8150 can take up to 8 chambers and can easily be upgraded to 16 ports for 8-16 chambers with a factory upgrade or field upgrade kit. Critical design features ensure measurement accuracy regardless of how many chambers are used.

Inside the LI-8150

The interior design of the LI-8150 Multiplexer features high quality, robust components for optimal performance and in-field serviceability:

• Durable, gasket sealed weatherproof case.
• Turck® weatherproof fittings for chamber electrical connections.
• O-ring sealed, quick-attach sample air line connectors.
• High flow, low power, long-life solenoid valves.
• LED indicator panel displays diagnostic information.
• Chamber actuator button closes all chambers for transport.
• Rotary vane pump samples air streams with minimal pulsations.
• Filter assemblies clean incoming air.

Multiplexed long-term system with LI-8150 Multiplexer (left), LI-8100 Analyzer Control Unit (right), and long-term chambers (background)

Four chamber system with 8100-104 Long-Term Chambers

Eight chamber multiplexed system

DC or AC Power

In a multiplexed system, DC power is supplied to the LI-8100 and LI-8150 via the LI-8150's power input terminal. LI-COR provides an optional 3 m DC cable with bare wire leads for connecting to a 10.5-14.5 VDC battery. AC power can also be used with an optional AC Power Supply (8150-770). The AC Power Supply provides a constant 12 VDC power source (4.5A maximum) and is designed for long-term outdoor deployment.

Atmospheric CO2 Profiling

In a multiplexed system, atmospheric CO2 profile measurements can be performed, in addition to soil CO2 flux measurements, with minimal added cost. Available Multiplexer ports (not occupied by chambers) can be used for this application. An atmospheric profiling kit is available (Part #8150-662) for use with the multiplexed LI-8100 System.
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