Private Sector R&DOngoing
Parking CO and NO₂ Gas Detection System Development
Accumulation of carbon monoxide (CO) and nitrogen dioxide (NO₂) from vehicle exhaust in closed car parks poses serious risks to both human health and regulatory compliance. HEFA Teknoloji is developing a CO and NO₂ gas detection device with an EN 50545-1 compliant TWA-based three-tier alarm algorithm, and a fail-safe central monitoring panel supporting up to 16 devices. The system is currently in the certification test preparation phase under EN 50545-1.
What We're Building
Gas Detection Device — CO and NO₂ Electrochemical Measurement
- Electrochemical CO sensor: high selectivity, ppm-level resolution
- Electrochemical NO₂ sensor: critical parameter in car parks with high diesel vehicle density
- Dual output architecture: 4–20 mA analogue signal (BMS integration) + Modbus RTU digital communication
- Independent relay outputs for Alarm 1 and Alarm 2
EN 50545-1 TWA Alarm Logic
- CO Alarm 1: 30 ppm / 15 min TWA — CO Alarm 2: 60 ppm / 15 min TWA — CO Alarm 3: 150 ppm / 1 min continuous
- NO₂ Alarm 1: 3 ppm / 15 min TWA — NO₂ Alarm 2: 6 ppm / 15 min TWA — NO₂ Alarm 3: 15 ppm / 1 min continuous
- False alarm prevention from instantaneous concentration fluctuations
- Alarm 3: 1-minute continuous threshold protection for emergency response at instantaneous dangerous concentrations
Central Gas Monitoring Panel — STM32F4 Based
- Simultaneous monitoring of up to 16 devices via Modbus RTU over RS485
- Fail-safe firmware architecture (EN 50271 referenced): automatic safe state on sensor fault, communication break or power loss
- Per-device independent alarm LED indicators and status LED
Technical Specifications
| Parameter | Value |
|---|---|
| Detected gases | CO, NO₂ |
| Sensor technology | Electrochemical |
| Alarm standard | BS EN 50545-1 |
| Alarm structure | 3-tier (TWA + continuous) |
| CO alarm thresholds | 30 ppm / 60 ppm (15 min TWA), 150 ppm (1 min continuous) |
| NO₂ alarm thresholds | 3 ppm / 6 ppm (15 min TWA), 15 ppm (1 min continuous) |
| Digital communication | Modbus RTU |
| Physical communication | RS485 |
| Relay outputs | Alarm 1, Alarm 2 (independent) |
| Panel microcontroller | STM32F4 |
| Panel capacity | 16 devices (simultaneous) |
| Panel firmware architecture | Fail-safe (EN 50271 referenced) |
| Project phase | Test and certification preparation |
Use Cases
- Closed Car Parks — CO and NO₂ monitoring and ventilation control in shopping centre, residential, office and airport car parks. The staged alarm structure allows automatic fan speed control based on alarm level.
- Underground Garages — Staged fan control and alarm management in areas with insufficient natural ventilation. NO₂ accumulation can reach critical levels during peak diesel vehicle hours.
- Vehicle Maintenance and Service Areas — Continuous monitoring against high concentration risk in engine running areas. Alarm 3 level enables emergency response at sudden dangerous concentrations.
Frequently Asked Questions
Why was a TWA-based alarm structure chosen over an instantaneous threshold?
TWA-based alarm structure is a BS EN 50545-1 requirement. Instantaneous threshold alarms can produce false alarms during short-lived concentration spikes, leading operators to desensitise to warnings. The TWA structure monitors average concentration over a defined period to reduce false alarm rates while reliably detecting genuine accumulation hazards. Alarm 3 provides 1-minute continuous threshold protection for instantaneous dangerous concentrations.
Why is the panel designed with a fail-safe architecture?
In gas detection systems, if a sensor fault or communication break goes unnoticed, the system may appear to be monitoring safely while it is not. The EN 50271-referenced fail-safe firmware automatically detects such fault conditions, moves the system to a safe state and notifies the operator.
How many devices does the panel support?
The panel can communicate simultaneously with up to 16 gas detection devices over the RS485 bus. Each connected device has independent alarm LEDs and a status indicator on the panel. RS485 bus architecture keeps cabling costs low.
Can the system integrate with existing ventilation infrastructure?
Yes. The independent alarm relay outputs on each device are designed to directly drive external equipment such as ventilation fans, sirens and warning lights. Staged scenarios — such as low-speed fan at Alarm 1 and full-capacity ventilation at Alarm 2 — can be configured through the relay outputs.
What is the EN 50545-1 certification status?
Device and panel development is complete. The client company is currently preparing for EN 50545-1 certification testing. TWA alarm accuracy, sensor performance and environmental durability parameters will be verified during testing.
This project covers a comprehensive R&D process including electrochemical gas sensor integration, EN 50545-1 compliant TWA alarm algorithm, RS485/Modbus RTU communication infrastructure, and EN 50271-referenced fail-safe panel firmware architecture. If you have a parking gas detection system or EN 50545-1 compliant system development need, we can evaluate your technical requirements together. gas detection device design service for more information.
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