Products- Bimetal thermometer

Overview

Because of the simple construction and high durability, bimetal elements are used not only with glass cartridge temperature gauges but also in applications where direct field readings must be accurate.

Principle and structure

Bimetal elements are two metals of differing coefficients of expansion that are bonded into one and rolled into a strip or rod. Figure 1 shows the initial state, but as the surrounding temperature rises, the metal of the high coefficient of expansion expands and elongates in the length direction, whereas the metal of the low coefficient of expansion expands little and bends upward to the state shown in Fig. 2. When the temperature returns as before, the bimetal element restores its original shape. We use a spiral bimetal, like that shown in Fig. 3, that works on this same principle.