Definition

Noun: A vacuum flask is a container designed to keep liquids hot or cold for extended periods. It consists of two walls with the air removed (a vacuum) between them, which greatly reduces heat transfer by conduction or convection.

Usage

A vacuum flask is used for storing and transporting beverages or other substances while maintaining their temperature. * She poured the hot coffee into her vacuum flask for the long drive. * Scientists often use vacuum flasks to store temperature-sensitive samples in the laboratory.

Advanced Usage

• Technical Context: In scientific and industrial settings, the principle of the vacuum flask (or Dewar flask) is crucial for thermal insulation in equipment like cryogenic storage tanks.
  • The liquid nitrogen was stored in a large vacuum flask to prevent rapid evaporation.

Variants and Related Words

• Thermos: A common brand name that has become a generic term for a vacuum flask.
  • He packed a thermos of soup for his hike.
• Dewar flask: The scientific name for a vacuum flask, typically used in laboratory contexts.
• Insulated bottle/container: A more general term describing any bottle designed to maintain temperature, which may or may not use a vacuum.

Synonyms

• Insulated flask
• Thermal container

Related Phrases

• Vacuum insulation: The technological principle that makes a vacuum flask effective.
  • The cooler uses vacuum insulation to keep ice frozen for days.

Noun

1. flask with double walls separated by vacuum; used to maintain substances at high or low temperatures