The QPA20… series room air quality sensors optimize room comfort by enabling demand-controlled ventilation. The sensors can acquire: CO₂ and volatile organic compound (VOC) concentrations, relative humidity, and temperature. Models are available for CO₂, CO₂/VOC, CO₂/T, and CO₂/T/RH.

The sensor evaluates the CO₂/VOC concentrations and transforms it to a 0 to 10 Vdc linear proportional output signal.

For models with humidity, a capacitive humidity sensing element changes capacitance as a function of the relative humidity. An electronic measuring circuit converts the humidity signal to a continuous 0 to 10 Vdc signal that corresponds to a relative humidity range of 0 to 100%. For models with temperature, the sensor acquires room temperature with a sensing element that changes electrical resistance as a function of the temperature. The resistance is converted to an active 0 to 10 Vdc output signal that corresponds to a temperature range of 32°F to 122°F (0°C to 50°C) or -31°F to 95°F (−35°C to 35°C).

Sensors with an LCD window display the following measured values:

• CO₂ in ppm
• CO₂ and VOC as a bar chart (4 bars ≈ 2V, 20 bars ≈ 10V)
• Temperature in °C or °F
• Relative humidity in %
The wall-mounted sensors are suited for use with all systems and devices capable of acquiring and handling a 0 to 10 Vdc output signal.