Additional specifications and description
Toxic gas monitoring in air ducts
CO and NO2 are toxic gases that are released by cars and other vehicles. They are especially a danger in underground parking garages. In this environment, a smart ventilation system must detect and prevent the accumulation of these toxic and deadly gases. It can do this by supplying fresh air in the garage when concentrations of CO or NO2 are rising. This duct sensor measures temperature and relative humidity and it monitors the trend of CO and NO2 concentration in air ducts. Based on the temperature and humidity, the dew point is calculated. This sensor will function best if it is installed in a straight section of the air duct. Avoid installing the sensor in turbulent air zones nearby filters, fans, cooling coils, etc. Position the sensor towards the airflow direction. Please consult the mounting instructions for more detailed information.
How does it work?
This sensor has three analogue outputs. Each of them transmits one of the measured values. Three output modes are available: 0-10 VDC, 0-20 mA, and PWM. By default, output 1 will transmit 0 V at 0 °C and 10 V at 50 °C. Each output value varies proportionally in function of the measured temperature, humidity or CO or NO2 concentration. The measured temperature is available via output 1, relative humidity via output 2 and the CO trend via output 3.
Monitor toxic gas concentrations
Next to Carbon monoxide (CO) and Nitrogen dioxide (NO2), this sensor will also detect changes in concentration of following gases: Ethanol, Hydrogen, Ammonia and Methane. When the concentration of these gases increase, the sensor output value will increase to increase the supply of fresh air. When the supply of fresh air reduces the concentration of toxic gases, the sensor output value will decrease again. The toxic gas sensor element is calibrated and tested in our factory. It doesn't require recalibration.
How to install a duct sensor? 
Sentera duct sensors are suitable for mounting in these two ways: using a flange or not using one. When the sensor is mounted on round ducts, the flange is required. The flange can be discarded if the duct is rectangular. Mount the opening of the sensor probe in the middle of the duct. The probe opening must be positioned in the same direction as the airflow for the sensor to optimally work. This allows the air to enter and exit the probe opening smoothly. Make sure that the sensor is installed in a place where only purified air passes. Impurities can disrupt the airflow over the sensor element and negatively affect its operation.
This sensor doesn't require configuration. Once installed, it is ready to use. The default settings will do for most applications. If necessary, the settings can be adjusted via Modbus RTU communication. For example, a different output type can be selected to make it compatible with other devices: 0-10 VDC / 0-20 mA / 0-100 % PWM. The Modbus register map provides a complete overview of all adjustable settings.
4-wire connection
The supply voltage is 24 VDC. The ground terminals of the power supply (V-) and output (GND) are internally not connected. This means that a 4-wire cable is required to connect this sensor. Most 24 VDC power supplies offer protection against short circuit, overload and overvoltage. A 24 VDC supply voltage increases the safety and reliability of your installation.
High quality
We use sensor elements and components of the highest quality. This ensures the long-term stability and accuracy of this HVAC transmitter. The enclosure offers IP54 protection against ingress of dust and moisture. The sensor element is integrated in the probe of the duct sensor. This probe has an opening to have direct contact between the air flow and the sensor element. The sensor probe offers IP20 protection.
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