SIGAS S-MODULE EVO Industrial-Grade NDIR Gas Sensor

Overview

The SIGAS S-MODULE EVO is an industrial-grade, dual-beam non-dispersive infrared (NDIR) gas sensing module engineered for high-accuracy, long-term stability, and minimal maintenance in continuous emission monitoring, biogas analysis, industrial safety, and process control applications. Unlike electrochemical or catalytic bead sensors, the S-MODULE EVO relies on the fundamental physical property of molecular absorption—specific gases absorb infrared radiation at unique, characteristic wavelengths (“spectral fingerprints”). By employing a thermally stabilized, gold-coated optical cavity and reference/detection channel architecture, the module achieves exceptional selectivity and immunity to chemical poisoning, mechanical wear, or sensor aging. Its core measurement principle conforms to ISO 12039 (for CO₂), ASTM D6245 (indoor air CO₂), and IEC 60079-29-1 (explosive atmospheres), supporting traceability in regulated environments. The module operates under constant flow conditions (0.1–1.0 L/min) and integrates real-time temperature and pressure compensation algorithms to deliver concentration outputs corrected for environmental drift—enabling reliable deployment across variable ambient conditions without frequent recalibration.

Key Features

• Dual-beam NDIR architecture with matched detector pairs for inherent drift rejection and improved signal-to-noise ratio
• Gold-plated, hermetically sealed optical cell with thermal mass optimization and low thermal conductivity mounting
• Integrated active heating (optional) maintaining internal sensor temperature at ≥35 °C above ambient—suppressing condensation and enhancing zero stability in high-humidity environments (up to 95% RH non-condensing)
• Aluminum housing with fiber-based thermal insulation and precision-machined 3 mm ID / 5 mm OD gas inlet port for repeatable, leak-tight tubing connection
• Fast response capability: T90 < 3 seconds in accelerated mode, validated per ISO 12039 Annex C and EN 14181 QAL1 requirements
• Low intrinsic noise: ±0.075% FS typical at T90 < 3 sec, enabling detection limits down to ≤1% of full scale (3σ)
• Modular electrical interface: native support for RS232, RS485, Modbus ASCII/RTU, and proprietary EVO protocols—all auto-baud and auto-frame capable
• Flexible analog output options including isolated 4–20 mA (3 kV_rms isolation), 0–10 VDC, and user-configurable voltage ranges via S-Connect PCB
• Comprehensive pressure compensation: selectable between ambient barometric correction or direct gas chamber pressure feedback (optional)

Sample Compatibility & Compliance

The S-MODULE EVO supports over 20 pre-calibrated gas configurations—including CO₂, CO, CH₄, SF₆, N₂O, SO₂, C₂H₄, SO₂F₂, and CH₃Br—each traceably calibrated against NIST-traceable standard gases. Calibration certificates comply with ISO/IEC 17025 requirements when issued by accredited laboratories. The module is designed for use with clean, dry, particle-free sample streams; optional particulate filters and hydrophobic membrane pre-filters are recommended for harsh industrial ducts or biogas lines. It meets EMC Directive 2014/30/EU and Low Voltage Directive 2014/35/EU. For hazardous area integration, the module itself is non-incendive (Class I, Division 2 compliant when installed with appropriate barrier systems); full ATEX/IECEx certification requires system-level validation with associated control hardware. All firmware and calibration data structures support audit-ready logging per FDA 21 CFR Part 11 and EU GMP Annex 11 when deployed with compatible host controllers.

Software & Data Management

While the S-MODULE EVO operates as a standalone analog/digital transducer, its communication suite enables seamless integration into SCADA, DCS, and IoT edge platforms. The embedded protocol stack supports configurable polling intervals (up to 10 Hz in fast mode), CRC-verified frame transmission, and error-code reporting (e.g., heater fault, flow alarm, saturation). Host software tools—including SIGAS EVO Configurator (Windows/Linux)—allow field adjustment of span/zero offsets, digital filtering coefficients, pressure compensation activation, and output scaling. Raw sensor diagnostics (detector voltage, reference signal, heater status, internal temperature) are accessible via extended Modbus registers. When paired with SIGAS-certified gateway hardware, the module supports TLS-secured MQTT publishing, time-stamped JSON payloads, and automatic firmware OTA updates—meeting IEC 62443-3-3 SL2 cybersecurity requirements for industrial sensors.

Applications

• Continuous emissions monitoring (CEMS) for combustion sources (CO₂, CO, CH₄)
• Biogas upgrading and quality control (CH₄/CO₂ ratio tracking, H₂S interference mitigation)
• Industrial hygiene and confined space entry (CO, CO₂, N₂O)
• Electrical utility SF₆ leak detection and purity verification in GIS switchgear
• Controlled atmosphere storage (CA) and fermentation process monitoring
• Welding gas mixture verification (CO₂-in-argon blends)
• Greenhouse climate management (CO₂ dosing control)
• Research-grade gas flux studies requiring sub-ppm repeatability and long-term baseline integrity

FAQ

What gases can the S-MODULE EVO measure?
The module is available in over 20 factory-calibrated variants covering CO₂, CO, CH₄, SF₆, N₂O, SO₂, C₂H₄, SO₂F₂, and CH₃Br—each optimized for specific concentration ranges and background matrices (e.g., N₂, Ar, biogas).

Does it require periodic calibration?
Yes—but extended calibration intervals are achievable: zero and span checks every 3–6 months are typical under stable conditions, supported by onboard drift diagnostics and automated zero-cycle routines.

Can it operate in high-humidity environments?
Yes—the optional active heating maintains internal dew point depression, and the insulated aluminum housing prevents external condensation ingress, enabling operation up to 95% RH non-condensing.

Is pressure compensation mandatory?
Not mandatory, but strongly recommended for applications where sample pressure varies >±50 mbar; ambient or chamber-specific compensation improves accuracy to ≤±0.2% of reading per mbar.

What power supply is required for heated operation?
A regulated 24 VDC source capable of delivering up to 1.3 A (≤31 W peak for longest chamber variants) is required when active heating is enabled.