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Siemens AQR253/4... Flush Mount Sensor

List Price: $210.00  
($219.45 inc tax) You save: $10.50 (5%)
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  •  Active flush-mounted room sensor comprising front module, base module and design frame accessory that can be ordered separately
  • Operating voltage AC 24 V or DC 15-36 V
  • Adjustable signal outputs: DC 0-10 V; DC 2-10 V; DC 0-5 V; DC 0-20 mA; DC 4-20 mA; DC 0-10 mA;
  • Maintenance-free CO2 sensing element based on optical infrared absorption measurement (NDIR1))
  • VOC2) sensing element based on a heated tin dioxide semi-conductor
  • Determination of air quality (IAQ3)) by maximum selection from CO2 and VOC sensing signals
  • CO2 value indicated by LED
  • Field of use 0…+50 °C / 0…95 % r.h. (non-condensing) / 0…2000 ppm
  • Active multi-sensor for CO2-temperature, CO2-humidity, and humiditytemperature
  • Passive temperature sensor (LG-Ni1000 / NTC 10k)

1) NDIR = Non-dispersive infrared
2) VOC = Volatile organic compounds
3) IAQ = Indoor air quality


In ventilation and air conditioning plants, to optimize comfort and energy consumption based on demand-controlled ventilation.

The room sensor records:
CO2 concentration to indicate presence in smoke-free rooms.
VOC concentration to indicate presence of odors in rooms, e.g. from tobacco smoke, body odor, material fumes.
Relative humidity in the room.
Temperature in the room.

Typical use:
Measure CO2 and VOC concentration: In party rooms, foyers, exposition and exhibition halls, canteens, shopping malls, sports facilities, sales rooms, meeting rooms, residential rooms.
Measure CO2 concentration: In rooms with varying occupancy with regard to time or number of persons, smoke-free rooms such as museums, theaters, movie theaters, lecture halls, offices, classrooms.

Devices for CO2 or VOC measurement are not suited for safety applications such as: Warning against presence of gas or smoke.


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