Siemens QFA3101 OUTSIDE AIR RELATIVE HUMIDITY SENSOR, 2 PERCENT, 4-20 MASiemens QFA3101 Outside Air Relative Humidity Sensor, 2 percent, 4 20 mA This Q Series Outdoor Air Relative Humidity Sensor monitors and transmits changes in humidity to the building control system. This unit is especially suited for HVAC applications where high accuracy and short response times for measuring relative humidity are required. It has a 2 percent accuracy rating and a 4 to 20 milli Ampere humidity output signal. Additional Information