Edinburgh Instruments Guardian Plus Infrared Multicomponent Gas Analyzer

Overview

The Edinburgh Instruments Guardian Plus is a high-stability, dual-channel non-dispersive infrared (NDIR) multicomponent gas analyzer engineered for continuous, real-time measurement of carbon dioxide (CO₂) and methane (CH₄) across wide dynamic concentration ranges. Leveraging proprietary optical path design and temperature-stabilized infrared detectors, the instrument achieves high selectivity and long-term baseline stability without cross-sensitivity to common interferents such as water vapor (H₂O), carbon monoxide (CO), or nitrogen oxides (NOₓ). Its core architecture follows Beer–Lambert law-based absorption spectroscopy at precisely tuned mid-infrared wavelengths—4.26 µm for CO₂ and 3.31 µm for CH₄—ensuring trace-level sensitivity and robust performance in demanding environmental and industrial settings. Designed for integration into continuous emission monitoring systems (CEMS), biogas upgrading plants, landfill gas recovery facilities, and food storage atmospheres, the Guardian Plus operates under ambient conditions without requiring sample conditioning (e.g., drying or filtering) in most standard applications.

Key Features

• Dual independent NDIR channels with dedicated optical paths for simultaneous CO₂ and CH₄ quantification
• Configurable measurement ranges: CO₂ from 0–3000 ppm up to 0–100% volume; CH₄ from 0–5% to 0–100% volume—user-selectable at time of order
• Integrated temperature and pressure compensation algorithms compliant with ISO 14040 and ASTM D6522 for volumetric concentration reporting
• IP65-rated aluminum housing suitable for indoor and outdoor wall-mount installation
• Low-power 24 VDC operation with built-in surge protection and reverse-polarity safeguard
• Factory calibration traceable to NIST-certified reference gases; optional on-site zero/span verification using certified span gases
• No consumables, no moving parts, and no required periodic lamp replacement—designed for >5 years of unattended operation

Sample Compatibility & Compliance

The Guardian Plus accepts dry or humid gas streams with dew points up to +30 °C and particulate loading <1 mg/m³. It is validated for use with biogas (CH₄/CO₂/N₂/H₂S mixtures), landfill gas, flue gas post-scrubbing, and controlled-atmosphere storage environments. All firmware and hardware configurations meet EU Machinery Directive 2006/42/EC, Electromagnetic Compatibility Directive 2014/30/EU, and UKCA marking requirements. Data integrity protocols align with GLP principles, supporting audit-ready operation in regulated waste-to-energy and environmental compliance reporting. While not intrinsically safe certified, it may be deployed in Zone 2/Class I, Division 2 areas when installed per IEC 60079-14 guidelines.

Software & Data Management

The analyzer supports native ASCII serial communication via RS-232 or RS-485 (Modbus RTU), enabling direct integration with SCADA, PLC, or DCS platforms. Optional Edinburgh Instruments GasView™ PC software provides real-time trend visualization, data logging (CSV export), alarm configuration (high/low thresholds with latching), and calibration history tracking. All configuration changes are timestamped and logged locally; firmware updates preserve user-defined settings. For regulated environments, optional 21 CFR Part 11-compliant audit trail functionality is available through third-party middleware integration—supporting electronic signatures, role-based access control, and immutable record retention.

Applications

• Landfill and anaerobic digestion biogas monitoring for energy recovery optimization and regulatory reporting (e.g., EPA Method 2C, EN 15267)
• Continuous stack emissions monitoring in waste incineration and cement kilns where CO₂ and CH₄ serve as process indicators
• Coal mine ventilation air monitoring for firedamp (CH₄) safety compliance
• Controlled atmosphere (CA) storage of fruits and vegetables, where precise CO₂ management extends shelf life per ISO 22000 requirements
• Leak detection and fugitive emission surveys in natural gas distribution infrastructure
• Research-grade greenhouse gas flux studies requiring stable, field-deployable multi-gas capability

FAQ

Does the Guardian Plus require periodic recalibration?
Calibration drift is typically <±2% FS/year under stable operating conditions. Annual verification against certified reference gases is recommended for compliance-critical deployments; full recalibration is only necessary if verification exceeds tolerance limits.
Can the instrument measure CO or N₂O?
No—the Guardian Plus is optimized exclusively for CO₂ and CH₄. For CO or N₂O analysis, Edinburgh Instruments recommends the Guardian SP series, which employs separate NDIR modules calibrated for those species.
Is the device compatible with explosion-hazardous areas?
The standard Guardian Plus is not ATEX or IECEx certified. For hazardous area deployment, consult Edinburgh Instruments for custom-configured versions with intrinsic safety barriers or pressurized enclosures.
What is the response time (T₉₀) for full-scale concentration changes?
Typical T₉₀ is ≤15 seconds for both CO₂ and CH₄ channels under laminar flow conditions at 0.5–1.0 L/min sample rate.
How is humidity handled in the measurement path?
The optical design incorporates H₂O-specific spectral rejection filters and embedded compensation algorithms; no external dryer is needed for relative humidity ≤85% RH at sensor inlet.