WL 201 Fundamentals of humidity measurement Vocational Training Equipment Thermal Lab Equipment
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 humidity.
The trainer WL 201 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.
different measuring methods for measuring humidity
climatic chamber with adjustable humidity and transparent door
humidification via ultrasonic atomiser
dehumidification via Peltier cooling element
fan for air recirculation
2 mechanical instruments: psychrometer, hair hygrometer
2 electronic instruments: capacitive sensor, hygrometer with synthetic fibre and combined temperature sensor
power consumption: 21,6W
low water cut-off
cooling capacity: 56,6W (50°C ambient temperature)
cooling surface: 1600mm2
Hair hygrometer with deflective needle
measuring range: 0…100% r. h.
Hygrometer with synthetic fibre
output voltage: 0…10V
measuring ranges: 0…100% r. h. / -30…80°C
Capacitive sensor with digital display
output voltage: 0…10V
measuring range: 1…100% r. h.
Psychrometer with thermometer
measuring range: -10…60°C, graduation: 0,5°C
230V, 50Hz, 1 phase
120V, 60Hz, 1 phase; 230V, 60Hz, 1 phase
Dimensions and weight
Weight: approx. 110kg