Gira CO2-Sensor, Руководство пользователя

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Order No. 2104 ..
4.2.4 Functional description
4.2.4.1 Application basics
Combination sensors that measure physical measured values at the installation location are
integrated in the device. In this way, the CO
2
content of the ambient air as well as the
temperature and humidity in a room can be measured and the measured values compared as
well. From the measured temperature and air humidity values the dew point can be calculated,
which is further processed in the device and can also be transmitted to the bus if necessary.
The measured values of the physical sensor are output on the bus via separate communication
objects. The integrated room temperature controller is operated entirely via communication
objects. Indicators and controls are not present on the device. Two push-button/switching states
can be read potential-free via both binary inputs, and depending on this, telegrams can be
transmitted to the bus.
The device is flush mounted in a switchbox and covers the surface of a socket. The device is a
so-called monoblock product. It does not require any separate bus coupling or additional power
supply.
In rooms frequented by many people, such as conference rooms, meetings or classrooms, the
CO
2
concentration can increase rapidly. People emit carbon dioxide into the air when they
exhale. The outside air normally inhaled contains about 21 % oxygen and 0.035 % carbon
dioxide. The exhaled air contains about 16 % oxygen and 4 % carbon dioxide. Even though
carbon dioxide first becomes extremely life threatening from a concentration of about 20 %, the
well-being, power of concentration and physical fitness already becomes impaired from 0.08 %,
which is first unnoticeable for the person affected, however.
Hence, various standards recommend a maximum value of 0.1 % carbon dioxide in the room
air. In view of today's construction standard and high air tightness of the building shell, this
value is very often exceeded. The result: as from a ratio of 1,000 ppm (0.1%), people become
tired, lack concentration and subsequently complain of a headache. In the case of higher
concentrations, increased heart beat, shortness of breath and unconsciousness occur (the so-
called CO
2
anaesthesia). CO
2
concentrations of 8 percent and more can cause death within 30
to 60 minutes.
Automatic monitoring of the air quality and automatically controlled ventilation can prevent this
effect. The work area of the CO
2
sensor is between 0% and 0.2% because rooms with these
CO
2
concentrations should already be ventilated (Figure 7).
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Software "KNX CO2 sensor"
Functional description