Gas-actuated temperature gauge

With a gas-actuated temperature gauge the stem, the capillary and the Bourdon tube are joined together into one unit. The instrument is filled with inert gas. If the temperature changes, the internal pressure will also change. The pointer is moved by the action of the pressure via a measuring tube. To compensate for the ambient temperature, a bimetal element is mounted between the movement and the measuring tube. Gas-actuated temperature gauges are available with scale ranges between -200 … +700 °C in accuracy class 1.