Open Path CH4Gas Analyzer

The LI-7700 Open Path CH4 Analyzer features an open sample path that measures methane density in ambient air.

The LI-7700 is designed specifically for eddy covariance flux measurements to evaluate methane emissions from the terrestrial landscape. It provides low-maintenance long-term operation in demanding field deployments. Low power consumption: Draws 8 watts of power nominally, making it ideal for use with solar power supplies in remote locations. High precision measurements: 5 ppb RMS noise at 10 Hz in typical ambient concentrations. Self-cleaning optics: Monitors signal strength and automatically cleans the lower mirror when the signal drops below a user-settable threshold. Heated mirrors reduce condensation on optics, which prevents data loss during humid conditions.

Innovative Solutions

Remote Field Deployment
  • Low power (8 W during normal operation)
  • Light weight (5.2 kg)
  • Low maintenance
  • Designed for long-term, unattended, continuous operation
Eddy Covariance
  • High precision (5 ppb RMS noise @ 10 Hz, 2000 ppb CH4)
  • High-speed data output (up to 40 Hz)
  • Simplified data integration
  • Analog inputs for sonic anemometer data
Open Path
  • In-situ methane density measurement using laser spectroscopy
  • Enables low power system operation
  • No time delays or attenuation from tubing
  • No pump required
Designed for Field Use
  • Radiation shield minimizes condensation on the upper mirror
  • Carbon fiber spars minimize thermal expansion of the optical path
  • Heaters keep mirrors near ambient temperature to prevent condensation

Why the LI-7700?

  • High precision and accuracy
  • Low power
  • Long-term, low maintenance operation
  • Easily integrates into flux towers
  • Simplified data integration
  • Light weight

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