TH-2005 NDIR Carbon Dioxide Analyzer

Overview

The TH-2005 NDIR Carbon Dioxide Analyzer is a precision optical gas analyzer engineered for continuous, real-time measurement of carbon dioxide (CO₂) concentration in ambient air. It operates on the principle of Non-Dispersive Infrared (NDIR) spectroscopy—a well-established, industry-standard method for trace gas detection. In this configuration, an infrared light source emits broadband IR radiation through a dedicated optical detection chamber containing the sampled gas stream. CO₂ molecules exhibit strong, characteristic absorption bands near 4.26 µm; the analyzer employs an interference filter and matched detector to isolate this spectral region. As per the Beer–Lambert law, the attenuation of IR intensity at this wavelength is directly proportional to CO₂ concentration over the instrument’s calibrated dynamic range—enabling high linearity, long-term stability, and minimal cross-sensitivity to common atmospheric constituents such as water vapor (when equipped with integrated humidity compensation) or methane.

Key Features

• Optimized NDIR optical path with temperature-stabilized IR source and thermopile detector for enhanced signal-to-noise ratio and drift suppression
• Integrated mass flow controller ensuring consistent sample draw rate (typically 0.5–1.0 L/min) and pressure-independent operation
• Dual-beam referencing architecture to compensate for optical aging, dust deposition, and ambient thermal fluctuations
• Onboard microprocessor-based control system with embedded firmware supporting auto-zero calibration, span verification, and diagnostic self-checks
• Rugged, weather-resistant enclosure rated IP54 for outdoor deployment in fixed-site environmental monitoring stations
• RS-232 and optional 4–20 mA analog output for seamless integration into SCADA, DAQ, or central data acquisition platforms

Sample Compatibility & Compliance

The TH-2005 is designed for direct analysis of ambient air without pre-concentration or chemical conversion. It accommodates particulate-laden or moderately humid samples when used with standard inlet filtration (e.g., 2.5 µm particulate filter) and optional Nafion® dryer modules. The analyzer complies with fundamental performance requirements outlined in EPA Method TO-11A (for ambient CO₂ monitoring), ISO 8573-1:2010 (compressed air purity, where applicable), and EN 14625:2012 (ambient air quality—measurement of CO₂ using NDIR). While not certified for regulatory reporting under U.S. EPA PS-15 or EU EN 15267, it meets technical specifications suitable for indicative monitoring, trend analysis, and QA/QC support in non-regulated applications—including indoor air quality assessments, greenhouse gas flux studies, and laboratory ventilation audits.

Software & Data Management

Data logging and remote supervision are supported via ASCII protocol over RS-232 serial interface, enabling compatibility with third-party software including LabVIEW, MATLAB, and industry-standard environmental data management systems (e.g., Campbell Scientific LoggerNet, EcoWatch). Firmware supports configurable sampling intervals (1–300 seconds), time-stamped output (UTC or local), and alarm thresholds with relay-triggered outputs. Audit-trail functionality records all calibration events, zero/span adjustments, and system errors—facilitating GLP-aligned documentation practices. Optional PC-based configuration utility provides real-time waveform visualization, spectral baseline diagnostics, and export of CSV-formatted datasets compliant with ASTM D6245-20 standards for CO₂ data reporting.

Applications

• Fixed-site ambient air quality monitoring networks (AQMS) operated by municipal environmental agencies and research institutions
• Indoor air quality (IAQ) assessment in schools, offices, hospitals, and public transport hubs per ASHRAE Standard 62.1
• Soil respiration and ecosystem CO₂ flux studies using closed-chamber or eddy-covariance auxiliary systems
• Verification of HVAC system performance and demand-controlled ventilation (DCV) logic in commercial buildings
• Calibration reference and field validation tool for lower-cost metal-oxide or electrochemical CO₂ sensors
• Teaching laboratories requiring stable, repeatable NDIR instrumentation for physical chemistry or environmental engineering curricula

FAQ

What is the typical measurement range and detection limit of the TH-2005?
The standard configuration covers 0–5000 ppm CO₂ with a resolution of 1 ppm and a stated repeatability of ±15 ppm or ±2% of reading (whichever is greater) under controlled conditions.
Does the analyzer require periodic calibration with certified gas standards?
Yes—zero calibration using synthetic zero air (≤0.1 ppm CO₂) and span calibration using NIST-traceable CO₂-in-N₂ standard gas (e.g., 2000 ppm) are recommended every 30–90 days depending on operating environment and data integrity requirements.
Can the TH-2005 operate unattended for extended periods?
It is engineered for continuous 24/7 operation with power supply redundancy options (100–240 VAC or 12/24 VDC), internal temperature regulation, and watchdog timer circuitry to recover from transient faults.
Is the device compatible with Modbus RTU or other industrial protocols?
Modbus RTU support is available via optional firmware upgrade and RS-485 interface module—contact technical support for configuration details and compatibility matrix.
How is moisture interference mitigated in high-humidity environments?
The base model includes software-based humidity compensation algorithms; for sustained operation above 85% RH, integration of a permeation dryer or chilled mirror dew point controller is advised to maintain measurement fidelity.