8
G
EGQ220F931
Rev. 2021 - V35
ATTENTION !
The minimum CO2
concentration of outside air in leafy, hardly industrialised areas is approx. 350
ppm (output voltage = 1.75
V
with MR = 0...2000 ppm
or 0.7 V with MR = 0...5000 ppm). The
gas inter-exchange in the sensor element happens by diffusion.
Depending on the changes to the concentra-
tion and the flow velocity of the air surrounding the sensor, the reaction of the device to the change of concentration may take place with a delay.
It is essential to choose an installation location for the device in which the air stream flows around the sensor. Otherwise the gas exchange may
be considerably delayed or prevented.
Commissioning
After the device is switched on, a self-test and temperature equalisation are performed. Depending on the ambient conditions, this process takes
30-50 min. (as an option, manual calibration can now be performed). If commissioning with automatic calibration, proceed as follows:
1.
Open all windows or set the air conditioning system to use outdoor air
2.
Switch on the device and move away from the device. If possible, all persons should leave the room.
3
The device is ready to use after 50 minutes.
Automatic calibration of the CO2 measurement
The regular exchange of fresh air is all that is required for the self-calibration technology in the sensor (CO2 concentrations: 350-500 ppm). The device
detects this condition and performs the calibration automatically. It is sufficient to open the windows or set the air conditioning system to use outdoor air
at regular intervals and to stop all CO2-producing processes that influence the ambient air. Proceed as follows:
Open all windows fully or set the air conditioning system to use outdoor air 1x weekly for 15-20 minutes.
If possible, all persons should leave the room during this time.
Regular ventilation of the rooms and flushing of the duct with fresh air will increase the measuring accuracy of the sensor.
Manual calibration of CO2 measurement
Manual calibration can be carried out independently of automatic calibration. Sufficient fresh air must be provided before and during the calibration
procedure (CO2 concentration: 350-500 ppm). Also make sure that no CO2-producing processes influence the ambient air. Proceed as follows to
perform manual calibration:
1.
Preparation: Remove the housing cover and open all windows or set the air conditioning system to use outdoor air.
2.
Press and hold the “
ZERO CO2
” button 5 seconds.
The calibration process has started. Keep the windows open or the air conditioning system set to use outdoor air.
3.
If possible, all persons should now leave the room.
4.
After 10 minutes, the calibration is complete and the device transmit a CO2 concentration of between 350-500 ppm.
Connecting diagram
EGQ220F931
Schematic diagram
EGQ220F931
1
2
3
+UB 24V AC/DC
Output CO2
[ppm] 0-10V
–UB GND
1
2
3
zero
Output CO2 [ppm]
+UB 24V AC/DC
–UB GND
