9
G
EGQ110F931
Rev. 2021 - V35
ATTENTION !
The gas inter-exchange in the sensor element happens by diffusion. Depending on the changes to the concentration 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 absolutely necessary to
choose the device mounting position to ensure that the air stream “presses” into the duct tube (see mounting diagram on page 3). Otherwise,
below-atmospheric pressure will develop in the duct tube that may cause a substantial deceleration of gas exchange or even prevent it.
General information on air quality
There is no universally uniform standard, which could be applied to a
VOC sensor
(Volatile Organic Compounds). The monitored air contains a large
number of substances to which the sensor responds, and gas mixtures are adjusted. Therefore this sensor does not act selectively, but rather
reflects the overall air quality. In principle, one also cannot state precisely what is "bad air" or what is "good air" because this is a purely subjective
sensation.
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 minutes
(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 VOC measurement (permanently active)
The regular exchange of fresh air is all that is required for the self-calibration technology in the sensor. 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.
Make sure that no harmful substances influence the ambient air during this process. Proceed as follows:
Open all windows fully or set the air conditioning system to use outdoor air 1x weekly for 15-20 minutes.
During this time, the release of gases from volatile organic substances must be prevented as far as possible.
Regular ventilation of the rooms and flushing of the duct with fresh air will increase the measuring accuracy of the sensor.
Every time the device is switched on, the automatic calibration cycle restarts and calculates a correction value across the operating period. In case of
power disruptions of less than 7 days, the calculation algorithm may be supported with a manual calibration to adjust the correction value more
quickly.
Manual calibration of the VOC measurement
Manual calibration can be carried out independently of automatic calibration. Sufficient fresh air must be provided before and during the calibration
procedure. Also make sure that no harmful substances influence the ambient air. Proceed as follows to perform manual calibration:
1.
Preparation: Prevent the release of gases from volatile organic substances as far as possible,
open windows and set air conditioning system to use outdoor air, remove the housing cover and wait 15 min.
2.
Press and hold the
“ZERO VOC”
button 5 seconds. The calibration process has started.
Keep the windows open or the air conditioning system set to use outdoor air.
3.
After 60 seconds, the calibration is complete and the device indicates or transmits the current VOC concentration.
Switching point setting
A switching point between 10 % and 95 % of the measuring range can be selected using the SET potentiometer.
A potential-free changeover contact is available as a switch output.
Offset
The VOC measured value can be adjusted subsequently using the offset potentiometer.
The adjusting range is ± 10 % of the measuring range.
