CUBIC INSTRUMENTS CUBIC-LGA Series Tunable Diode Laser Absorption Spectroscopy (TDLAS) Online Gas Analyzer

Overview

The CUBIC-LGA Series Online Gas Analyzer is an industrial-grade, intrinsically robust TDLAS (Tunable Diode Laser Absorption Spectroscopy) analyzer engineered for continuous, real-time measurement of multiple gas species—including O₂, CO, CO₂, H₂S, and CH₄—in demanding process environments. Unlike conventional NDIR or electrochemical sensors, the CUBIC-LGA leverages wavelength-specific laser absorption in the near-infrared spectrum to achieve selective, interference-resistant quantification based on Beer-Lambert law principles. Its optical path design eliminates moving parts and consumables, ensuring long-term stability under fluctuating temperature, pressure, and flow conditions. The analyzer integrates a front-end sample conditioning module—comprising particulate filtration, condensate removal, and flow regulation—to enable reliable operation in wet, dusty, or high-humidity process streams typical of upstream oil & gas, refining, biogas, and landfill applications.

Key Features

• TDLAS-based optical detection with high spectral selectivity, minimizing cross-sensitivity to background gases (e.g., H₂O vapor, CO₂, hydrocarbons)
• Intrinsically safe and flameproof enclosure certified to Ex db IIC T6 Gb (gas) and Ex tb IIIC T80°C Db (dust), compliant with IEC 60079-0, -1, and -31 standards
• Integrated zero-gas pump enabling automated air-based calibration without external gas cylinders
• Real-time self-diagnostic capability: continuous monitoring of laser intensity, photodetector response, optical alignment status, and signal-to-noise ratio
• Modular sample interface supporting 0.7–1.2 L/min optimal flow rate; compatible with standard 6 mm OD stainless steel or PTFE sampling lines
• Low-maintenance architecture: no consumable filters, reagents, or electrolytes; mean time between failures (MTBF) > 36 months under continuous operation

Sample Compatibility & Compliance

The CUBIC-LGA accepts raw process gas streams containing up to 95% relative humidity and ≤10 mg/m³ particulate loading when paired with the factory-configured pre-conditioning unit. Sample conditioning includes coalescing filtration (≥0.3 µm), thermoelectric cooling to dew point ≤5°C, and precision laminar flow control. All wetted materials comply with ASTM A269 TP316L and ISO 8502-3 cleanliness requirements. The analyzer meets electromagnetic compatibility per EN 61326-1 (industrial environment) and functional safety requirements aligned with SIL 2 per IEC 61508. It supports traceability to national metrological standards through NIM-certified reference gases (N₂ matrix, ≥99.999% purity), and its measurement uncertainty budget is documented per ISO/IEC 17025 Annex A.2 for accredited laboratory use.

Software & Data Management

Embedded firmware provides dual-mode operation: standalone local control via 4.3-inch backlit LCD with intuitive menu navigation, or remote supervision via Modbus RTU over RS-485/RS-232 and analog 4–20 mA current loop outputs. Optional Ethernet/IP or Profibus-DP modules are available for DCS/SCADA integration. Data logging supports timestamped CSV export (up to 1 year at 1-second intervals) with configurable alarm thresholds, event tagging, and audit trail functionality compliant with FDA 21 CFR Part 11 requirements—including electronic signatures, user role-based access control, and immutable change history. Firmware updates are performed via secure USB or OTA protocols with cryptographic signature verification.

Applications

The CUBIC-LGA Series is deployed across critical industrial segments requiring regulatory-grade gas monitoring: natural gas transmission pipelines (H₂S and O₂ corrosion monitoring), LNG liquefaction trains (CH₄ purity verification), refinery FCC units (CO combustion efficiency control), sour gas processing (real-time H₂S breakthrough detection), municipal landfill biogas upgrading (CH₄/CO₂ ratio optimization), and flare stack emission compliance (continuous CO and O₂ reporting per EPA Method 9 and EN 15267). Its ruggedized construction and explosion-proof rating make it suitable for Zone 1/21 hazardous locations per ATEX and IECEx directives.

FAQ

What gases can the CUBIC-LGA measure simultaneously?
The analyzer measures one gas species per optical channel; multi-gas configurations require modular sensor heads (e.g., dual-channel for CO + O₂ or CH₄ + CO₂).
Is calibration required before commissioning?
Yes—a two-point calibration using certified zero (N₂) and span gases is mandatory prior to field deployment; the built-in zero-pump enables automatic air-zero correction during routine operation.
Can the CUBIC-LGA operate in high-dust environments like cement kiln exhaust?
Yes, provided the integrated sample conditioning system is installed upstream; optional heated sample lines and ceramic filter upgrades extend applicability to particulate loads up to 50 mg/m³.
Does the device support third-party data acquisition systems?
Yes—Modbus RTU protocol ensures interoperability with Siemens Desigo, Honeywell Experion, Yokogawa CENTUM VP, and Emerson DeltaV platforms.
What is the recommended maintenance interval?
Optical window inspection and flow path validation every 6 months; laser diode lifetime exceeds 50,000 hours; no scheduled replacement parts within first 3 years of service.