The bimetal thermometer uses a threaded thermal bimetallic sheet as a temperature sensing device, and installs it in a protective sleeve, one end of which is fixed, called the fixed end, and the other end is connected to a thin shaft to become free end. A pointer is mounted on the free end spool. When the temperature changes, the free end of the temperature sensing device rotates accordingly, driving the pointer on the thin shaft to change the angle, and indicating the corresponding temperature on the dial.

The problems that occur during the use of bimetal thermometers are as follows:

1. During the storage, installation, use and transportation of the bimetal thermometer, try to avoid collision with the protection tube, and do not bend or deform the protection tube. During installation, it is strictly forbidden to twist the instrument shell.

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

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

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

5. All kinds of bimetal thermometers should not be used to measure the temperature of the medium in the open container, and the live contact thermometer should not be used in the control circuit of the occasion with large working vibration.

6. During storage, use, installation and transportation of the bimetal thermometer, avoid collision with the protective tube, do not bend the protective tube or use the watch as a wrench.

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