How to judge whether a bimetallic thermometer have bad

Bimetallic thermometer is a kind of field detection instrument suitable for measurement of low temperature, can be directly used to measure the temperature of the liquid and gas. Bimetallic thermometer now widely used in industry, agriculture and food industry etc. Bimetallic thermometer is to put the two different linear expansion coefficient of metal together, one end fixed, when the temperature changes, the two different kinds of metal thermal expansion, drive the pointer to indicate the temperature, that is the bimetallic thermometer. That how to judge the bimetallic thermometer is there bad? Instrument to several common situation for you about the below, if the following four cases, bimetallic thermometer must be damaged. A, temperature increase or reduce the bimetallic thermometer when the pointer is not moving. Second, under the environment of bimetallic thermometer cursor is not in normal temperature. Three, the temperature rise or reduce the jitter of bimetallic thermometer when the pointer. Four, accuracy is not allowed.