How to determine if the leak-proof design of a thermos flask is effective?

When choosing a thermos, leak-proof design is one of the key points that many consumers pay attention to. A well-leak-proof thermos not only protects your bag from water stains but also provides convenience in various usage scenarios. Here are some methods to judge the leak-proof design effect of a thermos:

First, the inverted test
Fill the thermos with water, tighten the lid, then place it upside down on the table and observe for a few minutes to see if there is any water leakage. If there is no water leakage, it indicates that the sealing ring is tight and the heat preservation effect is good. If there is any leakage, it may be necessary to replace the sealing ring or consider replacing the insulated cup.

Second, the shaking test
After tightly closing the lid, shake the thermos flask vigorously a few times and observe again if there is any leakage. By vigorously shaking, a considerable pressure is applied to the water inside the cup. If no water seeps out at this time, it indicates that the cup's sealing performance can withstand a certain pressure impact.

Third, observe the sealing ring
Make sure the sealing ring on the cup lid is intact. Any crack or missing part will affect the heat preservation effect. At the same time, pay attention to checking whether the sealing ring has aged or oxidized. An aged sealing ring not only leaks water but also causes temperature loss.

Fourth, check the screwing condition
Observe whether the lid and the rim of the cup can be screwed in smoothly and whether there is any gap. Flexible screwing can facilitate user operation, while the existence of gaps may be a potential risk factor for poor sealing, which may cause water to gradually seep out during use.

Fifth, temperature change measurement
Although this mainly tests the insulation effect, to a certain extent, it can also reflect the sealing performance. Fill the thermos with hot water, tighten the lid, let it stand for a while and then measure the water temperature. If the water temperature can be maintained at a relatively high level, it indicates that the thermos has good sealing performance, as good sealing performance helps to keep the temperature.

Sixth, actual usage test
After purchase, you can observe the leak-proof performance of the thermos during daily use. For instance, carry it in your bag for a while or use it during exercise to see if any water seeps out.
By using the above methods, you can comprehensively evaluate the leak-proof design effect of a thermos. When making a purchase, choosing products that have undergone strict testing and received good user reviews usually leads to better leak-proof effects. At the same time, regular inspection and replacement of the sealing ring can also ensure that the insulated cup maintains good leak-proof performance for a long time.