1. Using magnets, method: Take two thermos cups - one that attracts magnets and the other that does not attract magnets. The two thermos cups can be filled with water at about 80 degrees, and the lids of the cups are tightly closed. After three hours, the water temperature of the thermos cup that attracts the magnet becomes 40 degrees, while the thermos cup that does not attract the magnet is still above 70 degrees. From such an experiment, it can be seen that the effect of the thermos cup that attracts the magnet is not strong
2. Use boiling water: After filling with boiling water, tighten the cork or the lid of the thermos cup clockwise. After about 2-3 minutes, touch the outer surface and lower part of the cup body with your hands. Indicates that the thermal insulation performance of the thermos cup is not good enough. And can test the tightness of the thermos cup. Fill a glass of water, screw the lid tightly, invert it for a few minutes, or shake it a few times. If there is no leakage, it proves that the sealing performance is good.
3. Use accessories: Whether the accessories used are healthy and environmentally friendly. It is very important that the plastic parts of the vacuum flask are healthy and environmentally friendly. It can be identified by smell. If the thermos cup is made of food-grade plastic, its odor will be small, the surface will be bright, there will be no burrs, the service life will be long, and it will not be easy to age; if it is ordinary plastic, it will be inferior to food-grade in all aspects. plastic.
