ZOLIX ZLDM-126T NDIR CO₂ Sensor Module for Fresh Air Systems
| Brand | ZOLIX |
|---|---|
| Origin | Beijing, China |
| Manufacturer Type | Authorized Distributor |
| Country of Origin | China |
| Model | ZLDM-126T |
| Price Range | USD 1,400 – 2,800 |
| Technology | Non-Dispersive Infrared (NDIR) |
| Measurement Principle | Absorption Spectroscopy at 4.26 µm |
| Output Signal | Analog (0–5 V / 4–20 mA) and Digital (UART/I²C) |
| Operating Temperature | −10 °C to +50 °C |
| Humidity Range | 0–95 % RH (non-condensing) |
| Accuracy | ±(30 ppm + 3 % of reading) |
| Resolution | 1 ppm |
| Response Time (T90) | < 120 s |
| Zero Drift | < 2 ppm/month |
| Span Drift | < 2 %/year |
| Lifetime | > 15 years |
| Power Supply | 5 VDC ±5 % |
| Current Consumption | < 35 mA |
| Dimensions | 32 × 22 × 12 mm |
| Weight | ~8 g |
| Compliance | RoHS, CE (EMC/LVD), ISO 8573-1 Class 4 (for internal gas path) |
Overview
The ZOLIX ZLDM-126T is a compact, OEM-grade NDIR (Non-Dispersive Infrared) carbon dioxide sensor module engineered for integration into demand-controlled ventilation (DCV) systems, HVAC controllers, smart air purifiers, in-vehicle cabin air quality monitors, and indoor environmental health platforms. It operates on the fundamental principle of infrared absorption spectroscopy: CO₂ molecules exhibit strong, unique absorbance at 4.26 µm wavelength. The module integrates a thermopile-based infrared detector paired with a narrowband optical filter centered precisely at this absorption peak, enabling highly selective detection without interference from common atmospheric gases such as CO, CH₄, NO₂, or water vapor—provided relative humidity remains within specified operational limits. Its dual-beam architecture (reference + measurement channel) actively compensates for source aging, dust accumulation, and thermal drift, ensuring long-term baseline stability and measurement integrity over its rated 15-year service life.
Key Features
- True NDIR sensing core with integrated 4.26 µm bandpass filter and micro-machined absorption chamber — eliminates cross-sensitivity to non-target gases
- Dual-channel signal processing architecture for real-time drift correction and enhanced long-term reproducibility
- Low-power design (≤35 mA @ 5 VDC) suitable for battery-backed or energy-constrained embedded applications
- Compact SMT-compatible footprint (32 × 22 × 12 mm) with standardized pinout for rapid PCB integration
- Simultaneous analog (0–5 V / 4–20 mA) and digital (UART TTL / I²C) output interfaces — supports legacy and modern control systems
- Factory-calibrated traceable to NIST-traceable CO₂ standards; calibration certificate available upon request
- Robust mechanical housing with IP52-rated ingress protection for internal optics and electronics
Sample Compatibility & Compliance
The ZLDM-126T is designed for continuous monitoring of CO₂ in ambient indoor air, supply air ducts, and recirculated cabin environments. It complies with ISO 8573-1 Class 4 for particulate cleanliness in its internal gas path and meets RoHS Directive 2011/65/EU and CE marking requirements under EMC Directive 2014/30/EU and LVD Directive 2014/35/EU. While not certified to UL 2075 or EN 50131 for standalone alarm use, it satisfies functional safety prerequisites for incorporation into Class II medical devices (IEC 60601-1) and building automation subsystems aligned with ASHRAE Standard 62.1–2022 for ventilation rate procedures. For GLP/GMP-regulated environments, raw data logging and calibration history tracking must be implemented externally via host firmware.
Software & Data Management
The module supports ASCII-based UART command protocol (default 9600 baud, 8N1) for configuration, zero/span adjustment, and real-time data polling. I²C interface enables multi-drop topology in sensor fusion arrays. ZOLIX provides open-source driver libraries for Arduino, Raspberry Pi (Python/C++), and STM32 HAL, including example code for temperature/humidity compensation algorithms per ISO 16000-3 Annex B. Host systems may implement audit-trail logging compliant with FDA 21 CFR Part 11 when paired with timestamped storage and user-access controls — though the sensor itself does not store calibration or event logs internally.
Applications
- Demand-controlled ventilation (DCV) logic in commercial HVAC systems per ASHRAE Guideline 36
- Real-time IAQ feedback loop in residential smart thermostats and air purifiers
- In-cabin air quality monitoring for EVs and autonomous vehicles (UNECE R156-compliant software frameworks)
- Occupancy estimation in smart building management systems (BMS) using CO₂ as proxy metric
- Indoor agriculture climate controllers requiring precise CO₂ dosing (e.g., vertical farms, growth chambers)
- Portable IAQ survey meters used by industrial hygienists and IEQ consultants
FAQ
Does the ZLDM-126T require periodic field recalibration?
No — it features auto-compensation for thermal drift and optical degradation; however, annual verification against a certified reference gas (e.g., 1000 ppm CO₂ in N₂) is recommended for critical applications.
Can it operate in high-humidity environments?
Yes, up to 95 % RH non-condensing; prolonged exposure above 80 % RH without active desiccant or condensate management may affect long-term zero stability.
Is the module compatible with Modbus RTU or BACnet MS/TP?
Not natively — protocol conversion requires an external gateway; however, ASCII-over-UART allows straightforward translation to Modbus via standard serial-to-Modbus bridges.
What is the minimum detectable CO₂ concentration?
The lower limit of quantitation (LLOQ) is 400 ppm (ambient background), with full-scale range configurable from 0–2000 ppm to 0–10000 ppm via firmware command.
Does ZOLIX provide OEM customization services?
Yes — options include custom calibration ranges, modified output protocols, conformal coating for harsh environments, and co-branded labeling under NDA.
