DESIVENT MEASURING HUMIDITY

Instruments that measure environmental moisture levels are called Hygrometers.

The major types of Hygrometer are.

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Electronic digital - Modern day electronic hygrometers are small, lightweight and accurate and give easily read digital readouts. This technology is usually based on materials such as lithium chloride. These type of materials give different electrical outputs at different relative humidity's.

Psychrometer
Two thermometers are used side by side. One thermometer has a wet gauze on its base. The drying action of the wet gauze cools the thermometer, but crucially its rate of drying is affected by the humidity in the air. The temperature difference on each of the thermometers is noted and the humidity calculated from a table.

Human hair or nylon
Many of the ornamental hygrometers are based on the changing length of human hair at different humidity's. In recent times nylon has replaced hair as it is stronger and lasts longer.

Scientific hygrometers
There are many highly technical hygrometers for precision research. Some of the most well known types include dew-point, ion-exchange, infrared, microwave and thermal conductivity hygrometers.