Humidity measured value transducers of the 907031 series use the hygroscopic proper of specially prepared plastic fibres to define the relative air humidity. Once prepared, the installed humidity measuring element is capable of absorbing moisture. A change in length is the externally measurable effect. The humidity dependent change in length is sensed by a mechanical precision element and then transferred to the connection terminals as a linearized resistance output.

The standard output is 100…138.5 Ohm, which corresponds to a standardized Pt 100 signal. This allows direct connection to standard devices from the measuring, control and recording range for further processing of the measuring signal. Further device versions with different resistance outputs, with standardized current and voltage output signals as well as humidity measured value transducers complemented by temperature recording round off the delivery range.

The humidity measured value transducers are suitable for air conditioning applications as well as fur humidity measurements in industrial fields. The high resistance of the measuring element to water is an advantageous feature allowing permanent use of the device in high humidity applications through to saturation. Moreover, in normal circulated air the measuring is almost maintenance free. In the event of soiling caused by dusty air, the channel version allows for cleaning by washing the measuring element.

The operating range of the measuring element is between 30…100% rF given permissible ambient temperatures of between -40…+80°C. The passive device versions offer a major advantage as they do not require their own voltage supply to operate.

Frequent applications are found in climate air conditioning control, in ventilation, humidification and dehumidification technology as well as for storing fruit and vegetables, and in ripening rooms for foodstuff.