Type thermometer factory group WSS bimetallic thermometer can be used in high temperature?

WSS in the bimetallic thermometer can measure, liquid and gas in low temperature environment, but some customers will also bimetallic thermometer is used in high temperature environment, then the meter is always a failure and can't normal measurement, what caused this situation happened? WSS bimetallic thermometer is made up of two different type expansion coefficient of metal stitch welding together, when the measured temperature changes, because the expansion coefficient of metal is different, the free end by torsion deformation. In manufacture bimetallic temperature time, its material, geometry size has been determined, so the deformation of sheet metal is only associated with the change of temperature, if on the free end is equipped with drive mechanism, Pointers and tagged in temperature dial, can directly show the measuring temperature. From production and working principle of bimetallic thermometer can understand that the expansion coefficient of metal only when in low temperature can be approximately considered as constant, and by the high temperature, the expansion coefficient of metal will not remain in changshu, so in this case, the bimetallic thermometer measurement fault appears.