Relative Humidity Sensor

The RH40 series relative humidity sensor features a field interchangeable tip that requires no field re-calibration. State-of-the-art semiconductor technology is employed, together with a thin film polymer that changes di-electric constant with atmospheric relative humidity.


  • Inter-changeable tip
  • Linear output frequency
  • Robust construction
  • Reliable humidity measurements


  • Meteorology
  • Crop studies
  • Pest management
  • Ecology
  • Environmental studies


The technology employed results in a linear output change as a function of relative humidity. Response time is 1 to 2 minutes. When the relative humidity is at 100 %, and condensation (dew) occurs, condensation on the sensing element itself will give readings in excess of 100 %. Correct readings will return when the moisture has evaporated, and no permanent damage is done to the tip.

Mechanical protection from insects etc. and particulate contamination is provided by a series of filters. (NB: The standard Environdata warranty does not extend to relative humidity sensor tips and their replacement, as these are consumable items.)

Electronic relative humidity sensors are not recommended for accurate measurements above 95% relative humidity or for polluted environments.