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LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer

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Precise and accurate CO2 isotope measurements–in a portable analyzer

Measure the four most abundant CO2 gas isotopologues with high precision and accuracy in a portable analyzer that fits in a backpack. Designed for mobile monitoring and integration into soil gas flux systems, the LI-7825 enables researchers to explore new questions with confidence.

  • Identify sources and sinks of atmospheric carbon
  • Understand carbon movement in Earth’s systems
  • Partition net ecosystem carbon exchange
  • Monitor human impacts on the carbon cycle
  • Assess climate change mitigation strategies

Built on a proven platform

Backed by over 35 years of gas analysis technology, the LI-7825 utilizes Optical Feedback-Cavity Enhanced Absorption Spectroscopy (OF-CEAS) and patented innovations to deliver stability and affordability with minimal maintenance or calibrations.

Learn more about what makes LI-COR Trace Gas Analyzers different.

LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer open case

Source attribution with the LI-7825

Featuring Dave Lowry at Royal Holloway University of London

Read the case study
LI-7825 in the field

Expand into long-term soil gas flux research

The LI-7825 integrates with soil gas flux systems to take continuous CO2 isotope measurements, enabling real-time Keeling-based soil δ13C estimates and on-site calibration.

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How can you use the LI-7825?

  • Atmospheric monitoring
  • Urban emissions monitoring
  • Mobile emissions monitoring
  • Large area emissions monitoring
  • Sensor networks
  • Mud gas logging
Atmospheric monitoring

Measuring atmospheric CO2 isotopologues

The LI-7825 meets or exceeds requirements for long-term atmospheric background measurements and offers a versatile platform for a range of applications for a better understanding of CO2 emissions from anthropogenic and natural sources.

Figure 1-4. Ten-day CO2 Isotope stability data from an LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer. Data for the Allan Deviation plots were collected over a 10-day period, where, prior to the measurement of test gas, the LI-7825 was powered on to sample ambient air for 24 hours. For the study, it was connected to a 400 ppm CO2 tank with stainless steel tubing.

Measuring NH3

The LI-7825 measures higher concentrations of NH3, and is suitable for detecting ammonia in livestock barns, feedlots, barnyards, fertilizer applications, fence line monitoring, ammonia leaks, and other applications where NH3 concentration is elevated above natural abundance.

While the analyzer provides accurate NH3 measurements of the air reaching the sample cavity, users will need to account for the adsorption of NH3 to the sampling equipment in soil gas flux systems. NH3 measurements are not supported for LI-COR soil gas flux systems.

LI-7825 Specifications

General

  • Measurement Technique: OF-CEAS (Optical Feedback – Cavity Enhanced Absorption Spectroscopy)
  • Measurement Rate: 1 sample per second (1 Hz)
  • Optical Cavity Volume: 6.41 cm3
  • Flow Rate:
    • 250 sccm nominally for Standard Configuration
    • 70 sccm nominally for Reduced Flow Rate Configuration with installed kit
  • Total Weight: 10.5 kg (including batteries)
  • Case Dimensions: 51 cm × 33 cm × 18 cm (L × W × H)
  • Operating Temperature Range: -25 ℃ to 45 ℃ (without solar load, under normal operating conditions.)
  • Operating Humidity Range: 0 to 85% RH (non-condensing, without solar load, under normal operating conditions)
  • Sample Line Humidity Range: 0 to 99% non-condensing
  • Operating Pressure Range: 70 to 110 kPa
  • Connectivity: Ethernet and Wi-Fi (not available in some countries)
  • Wi-Fi Compatibility: 2.4 GHz, 802.11 a/b/g/n/ac
  • Power Consumption:
    • Steady State Operation: 22 Watts at 25 ℃ without batteries charging
    • Warmup: up to 65 Watts without batteries charging; up to 100 Watts with batteries charging
    • Off: Up to 2.3 Watts when powered from pins 3 and 4 without batteries charging; up to 0.2 Watts when powered from pins 1 and 5 without batteries charging
  • Power Supply Requirements:
    • Pins 1 and 5 (24 VDC Input): Minimum 6 A at 24 V
    • Pins 3 and 4 (10.5 to 33 VDC Input): Minimum 14 A at 10.5 VDC; 6 A at 24 VDC
  • Battery Life: 8 hours typical with 2 batteries
  • Pollution Degree: 2
  • Over-voltage Category: II
  • Class 1 Laser Product
  • CO2 Measurements
  • Range: 50 to 2,000 ppm
  • Precision (1σ): <0.05 ppm at 400 ppm with 5-minute averaging
  • Response Time (T10-T90): ≤2 seconds from 0-400 ppm
  • Maximum Drift: <0.5 ppm per 24-hour period
  • δ13C Measurements
  • Precision (1σ):
    • <0.5 ‰ at 400 ppm CO2 with 1-second averaging
    • 0.04 ‰ at 400 ppm CO2 with 5-minute averaging
  • Maximum Drift: <1 ‰ per 24-hour period
  • δ18O Measurements
  • Precision (1σ): <0.1 ‰ at 400 ppm CO2 with 5-minute averaging
  • Maximum Drift: <4 ‰ per 24-hour period
  • δ17O Measurements
  • Precision (1σ): <0.4 ‰ at 400 ppm CO2 with 5-minute averaging
  • Maximum Drift: <12 ‰ per 24-hour period
  • NH3 Measurements
  • Range: 0 to 30,000 ppb
  • Precision (1σ): 2 ppb at 300 ppb with 1-second averaging
  • Response Time (T10-T90): ˜5 minutes*
  • H2O Measurements
  • Range: 0 to 60,000 ppm
  • Precision (1σ):
    • 45 ppm at 10,000 ppm at 1 second
    • 20 ppm at 10,000 ppm with 5-second averaging

*NH3 measurement response time is dependent upon gas composition and inlet pneumatic configuration including tubing/fitting materials, flow rates, and upstream volumes.

Specifications subject to change without notice.

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