What is the cause of the poor insulation of the Dewar flask

Dewar flasks are widely used. Commonly used industrial gases such as oxygen, nitrogen, argon, carbon dioxide, etc. need to be stored in Dewar flasks. Because they are all cryogenic liquids, the insulation performance of Dewar flasks directly affects the gas storage cycle. The vacuum degree is only one aspect of the actual judgment of the insulation performance of the Dewar. The choice of insulation paper, the vacuum maintenance material, and the design of the bottom support of the inner tank all have a lot to do with it. After the vacuum reaches the standard, the quality of the insulation paper directly affects the insulation performance of the Dewar, and the selection of vacuum maintenance materials affects the vacuum maintenance time. As the Dewar is a pressure vessel, it moves more during use. Whether the design of the bottom support is reasonable also affects the heat conduction of the Dewar flask. Therefore, judging the insulation performance of the Dewar can not be confirmed by the vacuum alone.
 
1. Lifting of Dewar flasks: The design and manufacture of Dewar flasks can withstand conventional handling, but they will be damaged due to rough handling. When lifting the Dewar, the sling must be tied to the top ear, and it is strictly forbidden to directly act on the protection ring. Caution: Keep the Dewar equipment stable during lifting, and don't collide with other objects to avoid damage to the Dewar. 2. Dewar transport: When transporting Dewar, the supporting trolley or trolley can be used to assist the transport, and it is never allowed to roll the Dewar through the protective ring.
 
3. Dewar transportation: In order to prevent the Dewar from moving or colliding with each other during transportation, ropes are used to fix the equipment accordingly to ensure transportation safety.
 
4. Dewar storage: Dewar bottles should be stored in a well-ventilated place, and not exposed to the sun for a long time.