Vacuum cup, as its name implies, such bottle can keep water inside a certain temperature within specified time. When we value the quality of a vacuum cup, the major factor is the thermal insulation. First of all, we should make sure the material of steel to be SS304 or SS316, as these two types of stainless steel meet the national vacuum cup production requirements. Besides, the thickness of stainless steel is also an important element. Generally, thermos cup is made of inner and outer layers, welding technology is used to combine the liner and shell together, and then vacuum technology is used to pull out the air between the liner and shell to achieve the effect of vacuum insulation. stainless steel vacuum cup with thicker material can accept higher vacuum pressure, then higher vacuum insulation comes better insulation performance.
Then what is the principle of heat preservation for stainless steel bottles? In brief, the principle of thermal insulation is to block the transmission of heat in these three ways—radiation, convection and transfer. The silver inner of the thermos reflects radiation from the hot water, the vacuum between the double wall can blocks heat transfer, and in return blocks heat convection. Therefore, the quality of thermos cup mainly depends on whether the three ways of transmission are blocked, as long as the thermal transmission of thermos cup can be blocked perfectly, it can with excellent performance on heat preservation and cold preservation.
According to the steel insulation container standard, under room temperature of 20 degrees, pour into more than 95 degrees of boiling water in the thermos cup with capacity of less than 400ml, cover the lid tightly for 6 hours, the water temperature shall not lower than 42 degrees. While for cup capacity between 400-600ml, the water temperature should not lower than 54 degrees Celsius after 6 hours. This is the way to identify the quality of vacuum insulation performance, it just takes long time.
Here is another simple way. Pour the boiled water into the vacuum cup and tighten the lid for 2-3 minutes, then touch the outer surface of the cup body with your hand, if the cup body is obviously warm, it indicates that the production has lost vacuum degree and can not achieve good thermal insulation effect.