Instrumentation and automation: Measurement of humidity. XV 1st part

Air flows are used in many industrial processes, including those in the textile industry, and it is important to be able to determine the level of humidity in these flows. In addition it is also necessary to be able to measure the humidity of the ambient air in many production and storage areas. Humidity is the content of liquid in a gas and can be expressed as a relative or absolute value. There are many systems for measuring humidity based on one of a number of effects caused by the humidity on the materials. The article described psychrometric systems based on a wet and dry bulb thermometer, hygrometric systems based on changes in dimensions of hygroscopic materials, and systems based on dew point, heat of absorption, electrolysis, absorption, and infrared.