Siemens QFM3101 DUCT RELATIVE HUMIDITY SENSOR, 2 PERCENT ACCURACY, 4-20 MASiemens QFM3101 Duct Relative Humidity Sensor, 2 percent accuracy, 4 20 mA This Q Series Duct Relative Humidity Sensor monitors and transmits changes in humidity to the building control system. This unit is especially suited for applications where precise, stable humidity sensing is required. It has a 2% accuracy rating and a 4 to 20 milliampere humidity output signal. Additional Information Immersion length90206 mm Measurement range humidity0100 % r.