Calibratable duct humidity ⁄ temperature sensor HYGRASGARD® KFF ⁄ KFTF (± 2.0 %) or KFF – 20 ⁄ KFTF – 20 (± 1.8 %), with plastic sinter filter (optional metal sinter filter), terminal box enclosure made of impact-resistant plastic, enclosure cover with quick-locking screws, with ⁄ without optional display. It measures the relative humidity and ⁄ or the temperature of the air and converts the measurand into a standard signal of 0 – 10 V or 4…20 mA. It has four switchable temperature ranges and is applied in non-aggressive dust-free atmospheres in refrigeration, air conditioning, ventilation and clean room technology. Relative humidity (in % r. H.) is the quotient of water vapour partial pressure divided by the saturation vapour pressure at the respective gas temperature. These measuring transducers are designed for exact detection of humidity. A digital long-term stable sensor is used as measuring element for humidity measurement. Fine adjustment by the user is possible.