vaakumlülitid
Vaakumlülitid, also known as vacuum flasks or thermoses, are containers designed to keep liquids hot or cold for extended periods by minimizing heat transfer. The term "vaakumlülitid" is derived from the Estonian language, where "vaakum" means vacuum and "lülitid" means flask. These devices consist of a double-walled vacuum-insulated container, with a vacuum or gas-filled space between the walls to reduce heat conduction. The outer wall is typically made of stainless steel or glass, while the inner wall is usually made of glass or plastic. The vacuum or gas-filled space is created by removing most of the air, which is a poor conductor of heat. This design allows vaakumlülitid to maintain the temperature of their contents for several hours or even days, depending on the insulation quality and the initial temperature difference. Vaakumlülitid are commonly used for storing beverages, food, and other liquids, as well as for scientific and industrial applications where temperature control is crucial. They are available in various sizes and shapes, including cylindrical, spherical, and rectangular designs.