Humidity Measurement Apparatus Model TH 171

  • Different measuring methods for measuring humidity
  • Climatic chamber with adjustable humidity and transparent do.

Item Description

The measurement of air humidity plays an important role in many branches of industry, e.g. during drying
or in the air conditioning of buildings and vehicles. There are different measuring methods to determine

Sci-tech Humidity Measurement Methods Apparatus Model TH 171 enables the measurement of air humidity with four different instruments which can be directly compared to each other: two different hygrometers, a capacitive hygrometer and a psychrometer.

Psychrometers operate based on the principle of evaporation cooling and compare the ambient temperature with the wet bulb temperature to determine the humidity. Hygrometers utilise the property of specific fibres, e.g. hair, to expand with increasing air humidity. In the capacitive sensor the dielectricity constant of a layer and with it its capacity changes due to the water molecules absorbed.

The core element of the trainer is a climatic chamber with transparent door. This chamber can be humidified and dehumidified and contains the four instruments. A Peltier cooling element is used for dehumidification. An ultrasonic atomiser is used for humidification. To circulate the air and ensure good mixing a fan is used.

Technical Specifications

1. Different measuring methods for measuring humidity
2. Climatic chamber with adjustable humidity and transparent door
3. Humidification via ultrasonic atomiser
4. Dehumidification via Peltier cooling element
5. Fan for air recirculation
6. 2 mechanical instruments: psychrometer, hair hygrometer
7. 2 electronic instruments: capacitive sensor, hygrometer with synthetic fibre and combined temperature sensor


  • ultrasonic atomiser
  • power consumption: 21, 6W
  • low water cut-off


  • Peltier element
  • cooling capacity: 56, 6 W (50 degree C ambient temperature)
  • cooling surface: 1600 mm2

Hair hygrometer with defective needle

  • measuring range: 0…. 100% r.h.

Hygrometer with synthetic fibre

  • output voltage: 0…10V
  • measuring ranges: 0…100% r.h. /-30..80degreeC

Capacitive sensor with digital display

  • output voltage: 0…10V
  • measuring range: 1….100% r.h.

Psychrometer with thermometer

  • measuring range: -10….60degreeC, graduation: 0,5 degree C