RSMFF-3

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 offers a clear, visual indication of the CO₂ level via the green, yellow and red LED. The green LED indicates that the CO₂ level is within range – there is sufficient fresh air supply. When the CO₂ level enters the alert range, the yellow LED lights up. Red means that CO₂ levels are too high or that there is insufficient fresh air supply. The measured temperature, relative humidity, CO₂ and ambient light level are available via Modbus RTU. 

 

Photo-acoustic sensing technology is used to measure the CO₂ level. This makes the sensor very sensitive and specific, making it useful for the detection of various gases. The use of specific infrared wavelengths that correspond to CO₂ absorption lines ensures that interference from other gases is minimised.

 

In contrast to transmissive NDIR sensors, photoacoustic NDIR sensors measure the energy absorbed by CO₂ molecules. When the infra-red emitter is pulsed, CO₂ molecules absorb infrared light on a regular basis. This causes additional molecular vibration, which results in a pressure wave within the measurement chamber. The higher the concentration of CO₂, the more light is absorbed, and thus the amplitude of the acoustic wave increases. A microphone inside the gas chamber detects this, and the CO₂ concentration can then be calculated. Photoacoustic NDIR sensing allows for much more miniaturisation of the measurement chamber. Furthermore, because sound waves are omnidirectional, the relative position of the emitter and microphone is unconstrained. Thus, photoacoustic NDIR sensors are typically more mechanically and thermally robust. 

 

 

This sensor has three analogue 0-10 Volt outputs. Each of them transmits one of the measured values. E.g. by default, output 1 will transmit 0 Volt at 0 °C and 10 Volt 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. By default the output type is 0-10 Volt. Other output types can be selected via de Modbus holding registers.

 

 

This HVAC transmitter offers a clear, visual indication of the CO₂ level via the green, yellow and red LED. The green LED indicates that the CO₂ level is within range – there is sufficient fresh air supply. When the CO₂ level enters the alert range, the yellow LED lights up. Red means: CO₂ out of range or insufficient fresh air supply. The ranges can be adjusted via the Modbus holding registers. The LED indicators can visualize the status of one of the three measured values, by default CO₂.

 

 

The cage clamp terminal blocks reduce wiring and installation time. They eliminate the need for routine maintenance and guarantee a reliable contact for solid or stranded wires. 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. Two wires for the supply voltage and (minimum) two wires to connect the output(s). 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.

 

 

The ABC logic self-calibrating algorithm is enabled by default. This algorithm is intended for use in applications where CO₂ concentrations will fall to outside ambient conditions (400 ppm) at least once (15 minutes) in a 7-day period, as is common during unoccupied periods. The sensor will reach operational accuracy after 25 hours of continuous operation when exposed to 400 ppm 10 ppm CO₂

 

 

This sensor can be installed indoors on a wall or on a surface. The mounting holes are adapted to standard European wall mounting boxes. The sensor can be attached to the wall mounting box with two screws. The sensor enclosure will cover the entire wall mounting box. To ensure optimal performance, the sensor should be protected from direct sunlight.

 

 

The enclosure is designed for indoor use. It offers an IP30 protection against ingress of dust and moisture. The enclosure is exceptionally strong thanks to the use of high quality r-ABS plastic. Thanks to its contemporary modern design, this sensor can be used in most interior styles.

 

See how to connect your device in our video tutorial on our Youtube channel: