Airpots

An airpot, also known as a vacuum flask or thermos, is a portable insulated container designed to keep hot beverages hot or cold beverages cold for extended periods. It consists of a double-walled container, typically made of glass or stainless steel, with a vacuum sealed between the walls. This vacuum significantly reduces heat transfer through conduction and convection, thus minimizing temperature changes of the contents.

The inner and outer walls of an airpot are often coated with a reflective material, such as silver, to further reduce heat transfer by radiation. The opening of the airpot is usually sealed with a lid or stopper to prevent air from entering or escaping, which would compromise its insulating properties. Many airpots feature a pump mechanism, lever, or push-button that allows for easy dispensing of the liquid without removing the entire lid, minimizing further heat loss.

Airpots are commonly used in homes, offices, and for outdoor activities like picnics and camping. They are popular for keeping coffee, tea, soup, and other beverages at their desired temperature for hours. The effectiveness of an airpot depends on factors such as the quality of its construction, the initial temperature of the contents, and how frequently it is opened.