G
Installation and Commissioning
Rev. 2021 - V40
ATTENTION!
The minimum CO2
concentration of outdoor air amounts to approx. 350
ppm (output voltage = 1.75
V
at MR = 0...2000 ppm or 0.7 V at MR =
0...5000 ppm) in leafy, hardly industrialised areas. Gas inter-exchange in the sensor element happens by diffusion.
Depending on changes in the
concentration and flow velocity of the air surrounding the sensor, the reaction of the device to changes in CO2 concentration may appear with a delay.
It is absolutely necessary to choose the device mounting position to ensure that the air stream “presses” into the duct tube. Otherwise, below-
atmospheric pressure will develop in the duct tube that may cause a substantial deceleration of gas exchange of even prevent it.
Putting in operation
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 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 until the flashing LED row changes to a steady light after
5 seconds. Devices with a display indicate “
AUTO 0
” and change the countdown from 5 to 600.
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 (status LED has gone out, the countdown is complete) and
the device should indicate or transmit a CO2 concentration of between 350-500 ppm.
Display
The first line shows the
CO2
measured value
in ppm.
In the second line, the
switching status of the relay
is shown on the left as a circuit
(full
●
= relay energised; empty
○
= relay de-energised)
followed by the
indicator
(
C
for CO2)
and the
switchpoint value
is shown on the right.
Switching point setting
A potential-free changeover contact is available as a switch output.
A switching point between 10 % and 95 % of the measuring range can be selected using
the SET potentiometer. The 10 % value is added to the fresh air limit of 400 ppm for CO2.
(600...1900 ppm with MR = 0...2000 ppm or 900...4700 ppm with MR = 0...5000 ppm).
Offset
Subsequent adjustment of the CO2
measured value can be carried out using
the offset potentiometer. The adjustment range is ± 10 % of the measuring range.
Notes regarding mechanical mounting and attachment:
Mounting shall take place while observing all relevant regulations and standards applicable for the place of measurement (e.g. such as welding
instructions, etc.). Particularly the following shall be regarded:
– VDE ⁄ VDI directive technical temperature measurements, measurement set - up for temperature measurements.
– The EMC directives must be adhered to.
– It is imperative to avoid parallel laying of current-carrying lines.
– We recommend to use shielded cables with the shielding being attached at one side to the DDC ⁄ PLC..
Before mounting, make sure that the measuring device technical parameters comply with the actual conditions at the place of utilization, in particular
in respect of:
– Measuring range
– Permissible maximum pressure, flow velocity, temperature and humidity
– Protection type and Protection class
– Installation length, tube dimensions
– Oscillations, vibrations, shocks are to be avoided (< 0.5 g)
Attention! In any case, please observe the mechanical and thermal load limits of the protective tubes according to DIN 43763 or
according to specific S+S standards!
