The task of vacuum flask is to maintain a stable temperature for the liquid inside it, and for this reason, the vacuum flask manufacturer adopts a special design to reduce heat loss.
The construction of vacuum flask is not complicated. It is vacuumed between the two layers of the vacuum flask and plated with silver or aluminum, the vacuum state avoids heat convection, and the silver-plated vacuum flask can reflect the heat from the inside of the container. The silver inner wall in the vacuum flask can reflect the heat radiation of hot water, the vacuum state between the inner wall and the shell of the flask can block the transfer of heat, and the flask that does not exchange heat easily can prevent heat convection.
With these simple functions, stainless steel vacuum insulated flask prevent all heat transfer through conduction, convection or radiation. In addition, the lid of the vacuum flask is mostly made of plastic material. Plastic is also a bad conductor of heat, coupled with the multi-layer design of the lid of the vacuum flask, the air in the middle of the lip can reduce the thermal conduction of the plastic material, so the vacuum flask can maintain the temperature for a certain period of time. In fact, it is to slow down the heat exchange time.
If the vacuum flask or insulation bucket contains the ice, the principle is the same, it just reduce the heat exchange speed between the high temperature outside and the low temperature in vacuum flask (barrel).