13
G
AERASGARD
®
KTM - CO2 - SD
Rev. 2021 - V33
G
Installation and Commissioning
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 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. 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
The service life of the sensor depends on its functional principle and the type and concentration of pollutant gas burden. The sensitive layer of the
sensor element reacts with all volatile organic compounds and is therefore modified in its electrical properties. This procedure leads to an offset of
the characteristic line. When measuring the air quality, the general condition of the air quality is recorded. Whether the air quality is “good” or “bad”
depends on the individual interpretation of each individual. Different pollution burdens and concentrations influence the air quality signal (0 - 10 V) in
different ways. Examples are cigarette smoke, deodorant sprays, cleaning agents and various adhesive materials for floor and wall coverings, as well
as dyes. Increased levels of solvents, nicotine, hydrocarbons, aerosol propellants, etc. intensify the wear/ageing of the sensor element. Especially at
high pollutant gas burdens, even when the devices are idle (transport and storage) the zero point is adjusted. This must be corrected on-site depending
on the specific conditions or basic burdens. Air quality measuring instruments from various manufacturers cannot be compared directly with each
other because of the different functional principles, the pre-set basic burden (zero point) and the permitted burden (amplification/sensitivity). The
devices are set or calibrated according to the specifications of the sensor manufacturer. Here, a zero point and end value, and therefore a maximum
load, are established. In special circumstances, there is an overrun of the measuring range or an excessively high basic burden on the devices (out-
gassing carpets, wall paint, etc.) In order to enable a measurement or distinction of different air qualities, the devices must be configured by the client
in accordance with the on-site conditions which do not correspond to the function domain and thus the factory calibration. Here, it should be noted
that the factory calibration will be lost and technical data compliance can no longer be guaranteed.
Schematic diagram
KTM - CO2 - SD
DIP switch
KTM - CO2 - SD
CO2
content
DIP 4
0...2000 ppm (default)
OFF
0...5000 ppm
O N
4
5
6
OFFSET
CO²
°C
1 2 3
4
ON
ZERO CO²
DIP CO²
+U
B 2
4V A
C/
DC
–UB GND Output CO
² in ppm
free
Output temperature in °C
free
