Additional specifications and description
Optimised for air ducts
People produce CO2 or carbon dioxide while breathing. That makes CO2 concentration a good indicator for the occupancy and activity level in a space. In many applications, CO2 sensors are used as an indicator for the ventilation requirements. This HVAC transmitter measures temperature, relative humidity and CO2 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 installation in turbulent air zones nearby filters, fans, cooling coils, etc. Position the sensor correctly with respect to the airflow direction. Please consult the mounting instructions for more detailed information.
How does it work?
NDIR or Non-dispersive Infrared technology is used to measure the CO2 level. This technology has a low life-cycle cost and long-term precision and stability. The DSMFG-2R has three analogue outputs. Each of them transmits one of the measured values. E.g. 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 CO2 concentration. The measured temperature is available via output 1, relative humidity via output 2 and CO2 concentration via output 3.
This sensor requires very little configuration. It is almost directly usable once it has been installed. Temperature and relative humidity are often region- and seasonal-specific. These parameters are still adjusted to the correct values during installation. The other default settings will be suitable for most applications. However, they can also be adjusted via the respective Modbus registers if necessary. A different output type, for example, can be selected to make it compatible with other devices: 0-10 VDC; 0-20 mA; 0-100% PWM; Modbus RTU.
This sensor can be supplied with 24 V DC or with 24 V AC. It is intended for 3-wire connection. The ground of the output (GND) is internally connected to the ground of the supply voltage (V-). Make sure not to connect this common ground to other devices that are powered by a DC voltage.
Self-calibrating to compensate sensor drift
The ABC logic self-calibrating algorithm is by default enabled. This algorithm is designed to be used in applications where CO2 concentrations will drop to outside ambient conditions (400 ppm) at least once (15 minutes) in a 7day period, which is typically seen during unoccupied periods. The sensor will reach its operational accuracy after 25 hours of continuous operation at a condition that it was exposed to ambient reference levels of air at 400 ppm ± 10 ppm CO2.
The enclosure is optimised for CO2 measurements in air ducts. It offers an 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 a direct contact between the air flow and the sensor element. The sensor probe itself offers an IP20 protection.