Bimetallic thermometer takes the hot bimetallic sheet wound into a thread shape as the temperature sensing device and installs it in the protective sleeve. One end is fixed, which is called the fixed end, and the other end is connected to a thin shaft to become the free end. The pointer is mounted on the free end line. When the temperature changes, the free end of the temperature sensing device rotates, driving the pointer on the fine shaft to change the angle, and indicating the corresponding temperature on the dial.

The problems of bimetal thermometer in use are as follows:

1. During the storage, installation, use and transportation of bimetallic thermometer, try to avoid collision with the protective tube and do not make the protective tube The protective tube is bent and deformed. During installation, it is strictly prohibited to twist the instrument shell.

2. The instrument shall work normally within the ambient temperature of - 30 ℃ ~ 80 ℃.

3. The temperature at which the instrument often works should be at least 1 / 2 ~ 3 / 4 of the scale range.

4. The immersion length of bimetal thermometer protection tube into the measured medium must be greater than the length of temperature sensing element. Generally, the immersion length is greater than 100mm, and the immersion length of 0-50 ℃ range is greater than 150mm, so as to ensure the accuracy of measurement.

5. All kinds of bimetallic thermometers should not be used to measure the temperature of medium in open containers, and live contact thermometers should not be used in the control circuit where the working vibration is large.

6. During the storage, use, installation and transportation of bimetallic thermometer, collision with the protective tube shall be avoided, and the protective tube shall not be bent and deformed, and the watch shall not be used as a wrench.

7. The thermometer shall be inspected regularly under normal use. Generally every six months is appropriate. The electric contact thermometer is not allowed to work under strong vibration, so as not to affect the reliability of the contact.