Cause：
It is mainly caused by vibration during transportation and storage (low temperature thermometers should be stored in low temperature equipment). Therefore, the thermometer must be checked before the verification and use. If there is disconnection, it should be repaired in time. After the repair, it should be verified and used after passing the verification. Otherwise, it cannot be used.
Solutions：
Gravity method: When a liquid column with a broken line in the middle bubble or capillary is found, it can also be repaired by gravity method. First, place a layer of elastic soft material on the table top, hold the thermometer under the bubble, and slightly impact the elastic material vertically or Vibration will connect the disconnected liquid with the lower bubble. Sometimes a combination of gravity and cooling can also be used. First cool the disconnected liquid thermometer, take it out and use the gravity method. Repeat several times to remove air bubbles and connect the liquid.
Cooling method: Put the thermometer temperature bubble into the ice-water mixture or dry ice, so that the liquid column surface shrinks to the zero position and the upper part of the lower bubble, so that the bubble can be driven to the top of the liquid meniscus. In order to remove the bubbles, it can be repaired several times by combining the heating method and the cooling method.
Heating method: When it is found that there are liquid beads in the capillary or in the intermediate bubble, the heating method can be used. Put the thermometer temperature-sensing bubble in the heat source and heat it to connect the lower bubble liquid and the disconnected liquid, and then cool it at room temperature. If the connection cannot be made at one time, it can be repeated several times. It is often encountered, and it is worth noting that when the disconnected liquid drop is at the top of the safety bubble, it is difficult to repair, and a little carelessness will cause the lower bubble to burst, so be very careful when repairing.