ABSTRACT
This chapter deals with the parameter temperature, which, like the parameter pressure, affects all material on the earth. It looks at methods using mechanical means of measuring temperature; these rely on the physical changes solids and liquids undergo when they are exposed to a source of heat or cold. Temperature is a means of determining the amount of heat that a body contains for a given condition; it is not a direct measure of the heat of the body. Temperature can be measured in several ways, but the methods in general fall broadly into two categories, mechanical and electrical Under the category of mechanical methods are instruments based on the principles of thermal expansion of solids, liquids, and gases. Another way of measuring temperature is by detecting the change of resistance of a stable resistor when subjected to a change of temperature. The chapter considers thermoelectric temperature-measuring devices, which are being used more frequently for process control.
