Codel TunnelTech - Model 205 -NO2 Air Quality Monitor
The CODEL TunnelTech 205 NO2 Air Quality Monitor is a highly efficient transmissometer configured for the continuous measurement of Nitrogen Dioxide in road tunnel atmospheres. This extremely stable and reliable monitor incorporates a high-power blue LED to utilise the capacity of nitrogen dioxide to absorb UV and blue light to provide accurate readings in parts per billion. NO2 is produced naturally by the combustion processes within the internal combustion engine and is emitted from the exhausts of all types of vehicles.
NO2 is also particularly toxic and prolonged exposure to levels as low as a few hundred parts per billion will have a detrimental effect on human health. There is a growing international requirement to measure and limit the levels of NO2 within road tunnels to reduce the exposure of tunnel users to this toxic gas.
The TunnelTech 205 NO2 Air Quality Monitor utilises a very accurate measurement technique as UV and blue light are highly absorbed by NO2 . TheTunnelTech 205 is a precision transmissometer which measures the attenuation of UV and blue light by NO2 in the tunnel atmosphere. The light source is a near infrared LED where the interfering effects of particulate in the atmosphere are eliminated by making the measurement within a metre long diffusion cell into which the atmospheric gases, but not the particulate, can freely diffuse.
The result is a very accurate and stable sensor having no moving components and requiring no maintenance throughout its lifetime. Even the optic surfaces remain clean because they are contained within the diffusion cell which prevents the deposition of dirt on them. The filters through which the gas diffuses do not become blocked because the diffusion process exerts no forces on particulate to force them into the filter pores.
Fully configurable analogue and alarm outputs are generated inside the Station Control Unit (SCU) which are fully configurable via the supplied CODEL TunnelTech Software. In addition there is a choice of either RS232 or RS485 outputs which can be utilised to deliver MODBUS protocol to a SCADA system located in the tunnel control centre.
CODEL’s tunnel sensor range is further extended by additional sensors for the measurement of NO2 and tunnel airflow.
TunnelTech 301/2 Air Flow Monitors - For the measurement of wind speed and direction
TunnelTech 201 Air Quality Monitor - For the measurement of Carbon Monoxide, Nitric Oxide & Visibility
- Continuous measurement of NO2 in road and rail tunnels
- Class leading Accuracy, Repeatability and Resolution
- Rugged, corrosion resistant construction
- Minimal maintenance requirements
- Optional RS 485 (Modbus) Output
- Gas Species Options: Single or multi-gas measurements available: NO2
- Measuring units: ppb (Parts Per Billion)
- Response Time: Less than 200 seconds
- Ambient Temperature: -20°C to +50°C
- Power supply: 12V DC @1.5A
- Construction: Corrosion resistant epoxy coated aluminium housing sealed to IP65
- Analogue outputs: 2 x 4-20mA, 200V common mode isolation, maximum load 500Ω
- Relay Outputs: 2 x volt-free contacts SPCO, 0.25A @ 125V AC, 1A @30V DC, 0.25A @ 100V DC
- Serial Data: Via CODEL serial digital data bus
