External and internal parts of a vacuum flask and their functions

Thermos has become an indispensable helper for many people since its invention. Millions of people take advantage of it in distant journeys, walks with small kids or caring for elderly people. But only a few know exactly the parts of a vacuum flask and their functions. The most important information for thermos owners is how long it can hold the original temperature of food and water but in fact, it is very important to be aware of the flask structure to choose a quality and durable thermos to meet all the requirements issued to him.

Every thermos keeps heat or low temperatures for a long period of time thanks to the insulation. But to find an answer to the questions: “what is insulation and how does vacuum insulation work?” it is important to understand the structure of the flask with both external and internal parts contained by it.

Parts of the vacuum-insulated flask and their functions

The structure and constituent parts of every thermos might have differences depending on the model but still, there is a single basic way they are built. The most common flask parts are the following:

Screw or pushed in stopper

Parts of a vacuum flask and their functionsA thermos stopper is usually made of two different materials: plastic or cork. A plastic stopper is almost always screwed in while a cork one must be pushed into the flask. Some stoppers can be made of rubber or have rubber details for more reliable fitting.

Function: a tight stopper is used to prevent air from getting in or out of the thermos and avoid convection.

Two vessels joined by a neck and divided by the vacuum gap between them

Thermos vessels are very important parts of the flask. Both of them are usually made of such materials as glass or stainless steel. The last ones are more durable being unbreakable.

Vacuum existing between them is most often single. But there are new thermos versions with double wall vacuum insulated. There are two vacuum sections each filled with helium and liquid nitrogen correspondingly.

Function: the inner one keeps food or water and the outer ones does not allow them to cool down. The role of vacuum is to prevent conduction.
  • Reflective materials on the inner and outer vessel or between them

Flasks with glass walls are always lined with reflective materials like a metal layer, for example. Ones with steel walls have a single reflective line between two vessels.

Function: reflective materials prevent radiation. Energy is not lost and there is no heat transfer in a vacuum

  • Outer casing

Many flasks are hidden inside the plastic or metal case.

Function: a case has a decorative function.

  • Spacers

Long or sizable vacuum flasks are not only joined by a neck but also have inner spacers.

Function: they support the inner vessel adjusting it well to the outer one. However, such spacers are considered to be guilty of the partial reduction in insulating properties.

It is of utmost importance to evaluate every part of the flask for it to serve you well. Many people make a huge mistake being tempted by the only nice look of the thermos and get very disappointed when they start using it. Look through the list of high-quality vacuum flasks and choose the best food thermos that will never upset you.

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