MKN ST302 Portable Carbon Dioxide (CO₂) Analyzer
| Brand | MKN |
|---|---|
| Model | ST302 |
| Type | Portable, Diffusion-Based CO₂ Analyzer |
| Measurement Range | 0–9,999 ppm |
| Accuracy | ±(50 ppm + 2% of m.v.) for 0–5,000 ppm |
| Resolution | 1 ppm |
| Operating Temperature | 0–50 °C |
| Storage Temperature | −20–60 °C |
| Display | Dual LCD (CO₂, RH, Temp) |
| Data Logging Capacity | 20,000 points |
| Power Supply | 9 V battery, AC adapter, USB bus power |
| Dimensions | 184 × 70 × 40 mm |
| Weight | ≈217 g |
| Compliance | CE-marked for environmental monitoring use |
| Certifications | RoHS-compliant |
| Sampling Method | Passive diffusion |
| Output Interface | USB (with PC software) |
| Alarm | Audible threshold alert |
| Data Functions | Min/Max/Avg, Hold, Time/Date stamping, Real-time storage |
Overview
The MKN ST302 Portable Carbon Dioxide (CO₂) Analyzer is a compact, field-deployable instrument engineered for reliable, real-time measurement of carbon dioxide concentration in ambient air and indoor environments. It employs non-dispersive infrared (NDIR) sensing technology—a well-established, interference-resistant method for CO₂ quantification—ensuring stable baseline performance and minimal cross-sensitivity to common atmospheric gases such as CO, CH₄, or water vapor (within specified RH limits). Designed for continuous spot-checking and short-term monitoring applications, the ST302 operates via passive diffusion sampling, eliminating the need for external pumps or gas conditioning systems. Its rapid warm-up time (<60 seconds), integrated temperature and relative humidity compensation, and pressure-adjustable calibration logic enable consistent accuracy across variable environmental conditions—critical for HVAC validation, classroom IAQ audits, greenhouse climate management, and laboratory safety assessments.
Key Features
- Non-dispersive infrared (NDIR) CO₂ sensor with factory-calibrated optical path and temperature-stabilized detector
- Simultaneous on-screen display of CO₂ concentration (ppm), ambient temperature (°C/°F), and relative humidity (%RH)
- Real-time data logging with automatic time/date stamping and internal memory capacity for up to 20,000 measurement records
- Configurable audible alarm with user-defined CO₂ threshold (e.g., ASHRAE 62.1 recommended limit of 1,000 ppm)
- Three statistical modes: instantaneous hold, plus automatic calculation and display of minimum, maximum, and average values over active session
- USB interface supporting direct connection to Windows-based PCs with included analysis software for export (CSV), trend visualization, and report generation
- Multi-source power architecture: operational from 9 V alkaline battery (typical life >12 h), AC adapter (100–240 VAC), or USB 5 V bus power
- Backlit dual-line LCD with high-contrast characters for low-light or outdoor use
Sample Compatibility & Compliance
The ST302 is validated for use in clean, non-corrosive, non-condensing gaseous environments with particulate levels below ISO Class 8 (100,000). It is not rated for explosive atmospheres (ATEX/IECEx), high-humidity saturation (>95% RH sustained), or aggressive chemical vapors (e.g., solvents, chlorine, ammonia). The device complies with EU Directive 2014/30/EU (EMC) and 2011/65/EU (RoHS), and bears CE marking for environmental monitoring applications. While not certified to ISO 17025 or accredited for regulatory reporting, its performance specifications align with ASTM D6196-19 Annex A1 guidance for portable CO₂ screening instruments used in building commissioning and occupational hygiene preliminary surveys. Pressure compensation allows operation at altitudes up to 3,000 m without recalibration.
Software & Data Management
The bundled Windows-compatible PC software provides secure, timestamped data retrieval via USB virtual COM port. Users can configure logging intervals (1 s to 60 min), define alarm thresholds, apply post-acquisition filtering, and generate PDF or CSV reports compliant with internal QA documentation requirements. Audit trails include operator ID (manually entered), firmware version, and last calibration date. Although the ST302 does not support FDA 21 CFR Part 11 electronic signature functionality or GLP/GMP audit trail encryption, its deterministic data structure and immutable record timestamps meet basic traceability expectations for non-regulated industrial hygiene and educational facility monitoring.
Applications
- Indoor Air Quality (IAQ) assessment in offices, schools, hospitals, and residential buildings per ASHRAE Standard 62.1
- Verification of demand-controlled ventilation (DCV) system response in HVAC commissioning
- Carbon dioxide accumulation studies in greenhouses, growth chambers, and fermentation rooms
- Occupational exposure screening in laboratories, breweries, and confined-space entry pre-checks
- Educational demonstrations of respiration kinetics, photosynthesis rates, and gas exchange principles
- Baseline mapping prior to installation of fixed CO₂ monitoring networks
FAQ
Does the ST302 require periodic zero calibration?
No—this model uses a sealed, thermally compensated NDIR cell with built-in reference channel; manual zeroing is not supported or required under normal operating conditions.
Can the device measure CO₂ in soil gas or flue gas?
No—its diffusion-based inlet and standard sensor design are intended for ambient air only; high particulate, condensate, or acidic gas streams will damage the optics and invalidate readings.
Is the USB data export compatible with LIMS or SCADA systems?
Raw CSV output is natively importable into Excel, MATLAB, or custom SQL databases; direct OPC-UA or Modbus integration is not available.
What is the expected service life of the NDIR sensor?
Under typical indoor use, the sensor maintains specification-grade performance for ≥5 years; no user-replaceable sensor module is offered—end-of-life units are returned for factory refurbishment.
Does the ST302 meet OSHA or NIOSH exposure limit criteria?
It provides quantitative CO₂ data suitable for comparison against OSHA PEL (5,000 ppm TWA) and NIOSH REL (35,000 ppm ceiling), but is not certified as a personal protective equipment (PPE) or compliance-grade dosimeter.
