1. Check that the tip of the bottle (ie, the suction nozzle) at the end of the bottle is intact. If there is a break, the vacuum between the bottle and the interlayer is destroyed, and the insulation capacity is lost.
2. Check the bottle for cracks.
3. See if the bottle is round. If the bottle mouth is not round, the stopper can not be sealed, which will reduce the insulation capacity.
4. Check if the asbestos pad is displaced or detached. The asbestos pad is the three round black spots in the middle of the bottle, which is supported between the inner and outer gallbladder. If displaced or peeled off, the bottle will burst due to the inability to withstand the water pressure.