1. Listening method.
Attaching the empty bottle to the ear, the greater the better echo!
This is a way to check whether the water bottle is broken. Those voices are formed by the flow of air echo, the greater the better echo!
2. Hot water speed test.
Introducing a half bottle hot water into an empty bottle and close the lid. After about three minutes, try holding the thermos with both hands. If you feel hot, poor insulation performance; if you do not feel hot, indicating good insulation properties.
As a China thermos flask manufacturer, KINGMAX HOUSEHOLD PRODUCT CO., LIMITED. can wholesale china thermos flasks include stianless steel double layer vacuum flask, glass inner vacuum thermos flask, vacuum double wall stainless steel thermos flask, double wall stainless steel thermos flask and so on.