Digital Humidity Sensors

HYT 939 Hermetically Sealed Digital Humidity Sensor

HYT 939 has a welded, hermetically sealed TO 39 housing with glass grommet and sinter filter designed for compressed air systems up to 16 bar. Due to the humidity calibration process and special polynomial correction method, a high accuracy of ±0.1% rH is achieved in the the low humidity region of 0-10% rH up to 50 ppm water content. The sensor is suitable for dew point measurements up to -40C dp, such as for the evaluation of medical compressed air quality.

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Because of its robust construction, the sensor withstands peak loading at high temperatures. Therefore, this special model is also ideal for extremely sophisticated industrial applications in drying systems and suitable for medical systems. For pressure up to 16 bar, please order the HYT939p.

I2C compatible interface is standard.


  • Measurement range of 0 to 100% rH, -40°C to 125°C
  • Accuracy ±1.8% rH and ±0.2°C
  • Accuracy ±0.1% rH + 17% aw from 0-10% rH
  • Resistant to pressure up to 16 bar, HYT939p version
  • I2C interface
  • High chemical resistance
  • Dew formation resistant
  • Low operating voltage of 2.7 to 5.5V
  • TO39 housing
  • RoHS conformance

Technical Features

Measuring Principle: Capacitive polymer humidity sensor
Humidity Range: 0-100% relative humidity
Humidity Accuracy:

±1.8% rH from 10-80% rH

Accuracy 0-10% rH from 0-50°C ±0.1%rH + 17 aw
Humidity Resolution: 0.02% rH
Temperature Measurement Range: -40 to +125°C
Temperature Accuracy: ±0.2°C
Temperature Resolution 0.015°C
Hysteresis: less than ±1% rh
Response Time: less than 10 sec with sinter filter
Digital Interface: I2C, Address0x28 Alternative address
Meets RoHS conformity: Yes


  • Medical systems
  • Autoclaves
  • Pressure dew point measurement
  • Drying systems
  • Laboratories