ZOLIX ZLDM-118 NDIR Methane Gas Sensor Module

Overview

The ZOLIX ZLDM-118 NDIR Methane Gas Sensor Module is an industrial-grade, micro-form-factor infrared gas sensing unit engineered for continuous, real-time detection of methane (CH₄) and related hydrocarbon gases in hazardous and safety-critical environments. Based on the physical principle of non-dispersive infrared (NDIR) absorption spectroscopy, the module exploits the characteristic fundamental vibrational absorption band of methane near 3.3 µm wavelength. Its core optical architecture integrates a thermally stabilized broadband IR source, precision interference filter, dual-channel pyroelectric detector (active/reference), and proprietary signal conditioning electronics—ensuring high selectivity against cross-interference from CO₂, water vapor, and common background gases. Designed for OEM integration into fixed gas analyzers, portable monitors, or standalone alarm controllers, the ZLDM-118 delivers stable baseline performance over extended operational lifetimes (>5 years typical MTBF) without consumables or optical recalibration.

Key Features

• True NDIR detection with built-in temperature-compensated linearization algorithm—output signals are pre-processed to minimize nonlinearity across full scale (R² > 0.9995)
• Dual-range configuration support: factory-configurable for either 0–5% vol (high-resolution leak detection) or 0–100% vol (LEL monitoring), with corresponding resolution of 0.01% vol and 0.1% vol respectively
• Hybrid output interface: simultaneous analog (4–20 mA current loop standard, or voltage options) and digital (RS485 Modbus RTU protocol) outputs enable flexible system-level integration with PLCs, SCADA, DCS, or embedded microcontrollers
• Robust environmental resilience: operating temperature range of −40 °C to +70 °C and immunity to RH fluctuations below dew point—validated per IEC 60068-2 test standards
• Intrinsically safe design certified to GB 3836.4–2000 “i” protection level, suitable for Zone 0/1 classified areas when used with approved associated apparatus
• Zero maintenance requirement during service life: no moving parts, no chemical reagents, no periodic sensor replacement—only routine functional verification per site-specific safety protocols

Sample Compatibility & Compliance

The ZLDM-118 is optimized for direct measurement of methane in ambient air, process streams, and vented exhaust gases containing up to 95% relative humidity (non-condensing). It exhibits negligible response to CO₂ (cross-sensitivity < 0.5% of CH₄ reading at 1,000 ppm CO₂), ethanol, propane, and butane—enabling reliable use in mixed-hydrocarbon environments such as biogas upgrading facilities or natural gas distribution stations. Regulatory compliance includes full alignment with Chinese national standards GB 15322.1–2019 (Performance requirements for point-type combustible gas detectors), GB 3836.1–2010 (General requirements for explosion-proof electrical equipment), and GB 3836.4–2010 (Intrinsic safety “i” protection). While not CE-marked or ATEX-certified, its intrinsic safety architecture supports third-party certification pathways for international deployment under IEC 60079-0 and IEC 60079-11.

Software & Data Management

The module operates autonomously without host software dependency; however, its RS485 Modbus RTU interface supports standardized register mapping for readout of raw ADC counts, compensated concentration values (ppm or % vol), internal temperature, diagnostic status flags (e.g., fault, warm-up complete, calibration overdue), and firmware version. When integrated into larger systems, it fully supports audit-trail-capable data logging compliant with GLP/GMP principles—particularly when paired with controllers implementing time-stamped event recording, user-access control, and change history tracking. No proprietary drivers or closed SDKs are required; communication follows open Modbus specification v1.1b, enabling seamless interoperability with industry-standard HMI platforms.

Applications

• Natural gas pipeline integrity monitoring and compressor station leak surveillance
• Coal mine ventilation shaft and goaf zone CH₄ concentration tracking per safety regulation mandates
• Landfill gas collection system optimization and flare efficiency verification
• Biogas plant digester headspace analysis and upgrading process control
• Power generation turbine enclosures and switchgear rooms for explosive atmosphere prevention
• Industrial kitchens and LNG refueling stations requiring continuous combustible gas vigilance

FAQ

Is the ZLDM-118 compatible with Modbus TCP networks?

No—it implements only Modbus RTU over RS485 physical layer. Protocol conversion to TCP requires an external gateway.
Does the sensor require field calibration after installation?

No. It is delivered fully calibrated using certified CH₄/N₂ standard gas at specified span points. Only functional verification (bump test) is recommended per OSHA/NIOSH guidelines.
Can the module operate in sub-zero outdoor environments?

Yes. Its rated operating range extends to −40 °C, and thermal stabilization circuitry ensures consistent spectral response across the full interval.
What is the expected service life under continuous operation?

Minimum 5 years under nominal conditions (25 °C, 50% RH, no condensation); lifetime may extend beyond 8 years with proper thermal management and clean airflow.
Is the analog output isolated?

Yes—the 4–20 mA output features galvanic isolation rated to 1,500 VDC, meeting IEC 61000-4-5 surge immunity requirements.