1. Product Overview
The INK464 Tunnel CO / Visibility / NO₂ Detector is a specialized environmental monitoring instrument for road and railway tunnels. Installed on tunnel walls, it collects real-time data on carbon monoxide (CO), nitrogen oxide (NO), and visibility (VI), with expandable NO₂ monitoring capability. The visibility analyzer uses transmission measurement, while CO and NO are detected using negative gas absorption via specific spectral wavelength peaks. Built-in status display, self-check, and automatic calibration ensure precise, consistent measurements. This data is delivered to traffic monitoring authorities to optimize tunnel ventilation, maintain safe air quality, and ensure smooth, safe road operations.
2. Sensing Technology & Self-Cleaning System
The INK464 uses optical-based sensing technologies optimized for tunnel environments:
- Visibility (VI) Sensing: The detector uses light transmission measurement, where a light source projects a beam across the tunnel. Airborne particles attenuate the light, and the sensor calculates visibility based on light intensity loss, providing accurate visibility (K value) readings.
- Gas Sensing (CO/NO/NO₂): CO, NO, and optional NO₂ are measured using negative gas absorption spectroscopy. The system targets specific spectral absorption peaks of each gas, ensuring high selectivity and accuracy even in mixed gas environments.
- Environmental Adaptation & Maintenance: The detector features built-in self-check routines and automatic calibration to maintain measurement precision over time. While it does not include an active self-cleaning mechanism, its IP68-rated fully sealed enclosure protects against dust, moisture, and tunnel contaminants, reducing the need for frequent maintenance in hard-to-access locations.
3. Key Features & Competitive Advantages
- Multi-Parameter Integration: Combines visibility, CO, and NO/NO₂ monitoring into a single compact unit, eliminating the need for multiple separate sensors and reducing installation complexity and cabling costs.
- High-Precision Optical Sensing: Uses optical transmission and gas absorption spectroscopy for reliable, drift-resistant measurements, unaffected by cross-interference from other tunnel gases.
- Expandable Monitoring: Optional NO₂ measurement capability allows customization to meet specific tunnel air quality monitoring requirements.
- Built-In Diagnostics & Calibration: Features LED status display, self-check functions, and automatic calibration to ensure long-term measurement accuracy and simplify maintenance.
- IP68 Protection Rating: Fully sealed against dust, water, and corrosive tunnel environments, enabling reliable operation in harsh, high-humidity conditions.
- Flexible Output Options: Supports analog (0/2/4-20mA) and optional digital (RS232/RS485) interfaces for seamless integration with tunnel SCADA systems, ventilation controls, and traffic management platforms.
- Audible/Visual Alarms: Configurable audible and visual alarms with adjustable thresholds, plus relay outputs for fault, contamination, and maintenance alerts, enabling proactive safety management.
- Real-Time Local Display: LCD screen provides on-site real-time measurement readings, simplifying on-site monitoring and troubleshooting.
4. Technical Specifications
| Parameter |
Specification |
| VI Measurement Range |
K = 0 ~ 35×10⁻⁶ /m |
| CO Measurement Range |
0 ~ 300 ppm; 0 ~ 600 ppm (optional) |
| NO Measurement Range |
0 ~ 200 ppm |
| NO₂ Measurement Range |
0 ~ 10 ppm (optional) |
| VIS Accuracy |
±1×10⁻⁴ /m |
| CO Accuracy |
±1 ppm |
| NO Accuracy |
±0.1 ppm |
| NO₂ Accuracy |
±0.04 ppm |
| Analog Output |
2 channels: 0, 2, 4 ~ 20 mA; max load 1000 Ω |
| Digital Interface |
RS232 / RS485 (optional) |
| Protection Class |
IP68 |
| Status Display |
LED device status display |
| Power Supply |
AC 220 V / DC 12 V |
| Operating Humidity |
0 ~ 100 %RH, non-condensing |
| Operating Temperature |
-50 °C ~ +75 °C |
| Data Display |
LCD real-time measurement display |
| Alarm Function |
Audible and visual alarm; adjustable alarm threshold |
| Relay Output |
CO fault; VI fault; maintenance/contamination/alarm indication |
| Response Time |
≤30 s |
5. Applications
- Road tunnel environmental monitoring for ventilation control and traffic safety
- Urban highway and underpass air quality monitoring for emissions management
- Railway tunnel safety monitoring for toxic gases and low-visibility conditions
- Smart city tunnel management systems for automated ventilation and safety control
- Industrial tunnel and utility conduit environmental monitoring
- Emergency response tunnel monitoring for disaster and rescue operations
- Toll plaza and low-visibility traffic environment air quality and visibility tracking
- Compliance monitoring for tunnel air quality and safety regulations
