What is a thermos and how to choose it?

The thermos is the most useful invention. Each of us, if necessary, resorts to his help. It keeps drinks and food hot or cold for a long time. In field conditions in winter it warms and feeds with warm food, in summer it provides chilled food. In the article we will tell you what thermoses are and how you should choose them.

The device was the first to be produced by a German company Thermos GmbH, and its name formed the basis for the name of the manufactured product. The thermos is a heat-insulating, hermetically sealed portable device. It can maintain a temperature different from the environment: both high and low. Heat-resistant dishes are used not only for storing food, but also for preparing it. Porridge steamed well in it, herbal teas are infused.

Today you can find different types of thermos, but they are all arranged with the same principle of operation: they consist of double walls, which allows you to evacuate air between the flask and the body and create a vacuum interlayer. Such a device minimizes heat exchange between the products inside the thermos and the external environment.

Flask - the main structural element, it is made of glass or stainless steel. The walls are covered with a mirror coating, creating reflective properties. This works well to reduce heat exchange. The case is most often made of metal or plastic and gives it an attractive, competitive look. The vessel is closed with a sealed lid. But it is she who is considered the weak link of the thermos. The more thought-out and tighter the lid, the longer heat or cold remains in the container.

The history of the modern household thermos began with a device not intended for food. The first glass container with double walls and evacuated air was invented by the physicist A.F. Weinhold of Germany in 1881. It looked like a box and was used to store liquid oxygen.

Scottish scientist and inventor James Dewar perfected the container and introduced it in 1893 as a double-walled, narrow-necked flask. Reducing the inlet allowed less liquid to evaporate. D. Dewar invented to cover the walls from the side of the vacuum space with a thin layer of silver, giving them reflectivity. At that time, the vessel was still used by physicists and chemists.

The product received a household focus only at the beginning of the twentieth century thanks to the German manufacturer Reingold Burger. He made changes to D. Dewar's product, adding a durable metal case, a sealed stopper and a glass lid to it. R. Burger invented a more reliable way of holding the inner flask and patented the product in 1903.

During this period, the question arose about the production of a unique vessel. R. Burger announced a competition for the best brand name. As a result, the name Thermos was adopted, which in translation from Greek means "warm". In 1904, R. Burger opened the Thermos GmbH company, which was engaged in the production of household thermoses. Until 1907, he managed to sell patents to several other firms in the United States and Canada.

D. Dewar had nothing from commercial activity and tried to sue R. Burger, but since he did not timely patent his invention, the court ruled against him. Today, all rights to the Thermos brand belong to the Japanese company Thermos L. L. C., which produces thermoses.

The thermos is convenient as a marching, tourist, sports version of a vessel that maintains the initial temperature of drinks and food. It is suitable for fishermen, hunters, people doing professional activities away from infrastructure. To please everyone and solve different problems, manufacturers produce a large number of types of their products.

They can be divided into three main categories: for drinks, for food and general purpose.

Thermos for drinks store liquid, they have a narrow neck. Meal devices have large inlets to make it easier to load solid food. Versatile products have combined the tasks and qualities of two types of thermos. They can store both liquids and solid foods.

For this, the vessel is equipped with a double-acting lid. To extract borscht or porridge, you need to remove the lid completely. To pour a cup of tea, you can use the narrow inlet located in the center of the lid. It is not always arranged in the form of a plug that must be opened. Instead, the surface can be equipped with a button and a spout for draining the liquid. The narrowed hole is necessary to protect the remaining drink from cooling quickly. For ease of use, universal thermoses are often endowed with side folding handles. The set may include a liquid cup, a deep plate, and even a plastic fork and spoon.

These thermoses are the most popular. They are needed for storing hot coffee, tea, for brewing herbs, or for cold water and drinks in the summer. The devices have a different appearance, but in most cases they can be found in a narrow version, which is most convenient for carrying, and with a small neck (25-55 mm) so that drinks can maintain a given temperature for a long time. Each device contains a cup in the form of a lid for convenience, and some larger models are completed with two cups.

Since thermos for liquid transfer are most in demand, manufacturers have developed various product options that differ in shape, size, design and materials. But more often than not, the differences lie in the way the fluid is supplied. Types of thermos for drinks are as follows.

• Bullet... The name of this type of product is translated as "bullet", but its dimensions are more like a projectile. The thermos contains a metal body made in the form of a bullet. It is compact, easy to carry in a backpack and bag, it is easy to hold it in your hand, pouring liquid into a cup. To get to the drink, it is not necessary to unscrew the cap: you just need to use the valve it contains. The lid of the model acts as a mug. Sometimes a case and a strap are added to the "bullet" for wearing on the arm or on the shoulder.

• Thermos flask... A small and often flat version of a thermos, convenient for constant wearing during hunting, fishing, or hiking. Thanks to its original appearance, the thermos flask can be a good gift for those who like to travel.

• With pneumatic pump. A capacious desktop thermos with a volume of 3 to 5 liters, designed for a large company and convenient for road transportation. The pneumatic pump is mounted in a lid with a spout. With its help, the liquid is removed from the vessel, even if very little of it remains. There is no need to open the cap and turn the vessel over during the period of use; for filling it is enough to press the button at the top of the thermos. Such devices are often produced with a built-in thermometer to monitor the temperature state of the liquid, because if the company is small, it will take a long time to drink from such a thermos.

• With a tap. Large desktop thermoses are not only pumped. In order not to overturn the overall vessel during filling, it is equipped with a small tap located at the bottom of the product.

• Thermo mug... Small cone shaped thermos for one person. To use the drink, you need to remove the lid and then use the container like a regular serving cup. Often a small hole is provided in the lid. You can insert a straw into it or pour the contents into another mug with it. The product is as compact as possible, it is convenient to carry it with you.

• Thermos-sititerm... Small half-liter thermos... Unlike a thermo mug, it contains double walls with a vacuum interlayer. Keeps the set temperature up to 8 hours. The product weighs 250 g without contents. It is taken with them on walks or bike rides.

There are two types of food thermoses.

• The first ones have a single compartment, into which it is convenient to pour soups or borscht for lunch. The width of the neck of the product is 6-8 cm, the set includes a deep bowl.

• The second ones are called ship-type ones, they contain 2-3 modules with sealed covers. All vessels are connected into a single thermal system. The second option is suitable for solid foods: rice, goulash, pancakes, dumplings, and other dishes.

Sometimes boat sets are completed with a spoon fixed to the body.

As we have already found out, a thermos consists of an outer body and an inner flask. These elements can be made from completely different materials. The body is made of metal or durable plastic. And the flask has many more variations: it can be steel, glass, plastic, copper, and even titanium or ceramic. Let's consider the options for flasks in more detail.

• Glass... More than a hundred years ago, flasks were made only of glass. And today this material is popular. Fragility is its only drawback, the rest of the indicators of glass flasks are positive.The material is easy to clean, does not absorb foreign odors, and maintains the set temperature for a long time. A large thermos with a full fill keeps you warm for 48 hours.

• Steel... For thermal products, stainless steel is used. Although it has a high thermal conductivity and is inferior to glass in terms of temperature preservation, it surpasses it in strength. You can take an iron thermos on a hike without fear of breaking it. Keep in mind, however, that steel models weigh more than plastic ones and are not easy to carry on foot. Teflon coated products have proven themselves quite well.

• Plastic... Thermoses with plastic flasks are lightweight, shock-resistant, and have a budget cost. But they cannot keep warm for a long time. Absorbs odors and retains them. For example, after storing coffee, any other poured drink will have a coffee flavor. In addition, not every polymer is suitable for use at high temperatures.

• Copper... Vacuum flasks with a copper flask are not very common; in terms of their characteristics, they are similar to steel products.

• Ceramics... Ceramic species have the same properties as glass, and their ability to retain heat is even higher. The disadvantages of ceramics include the fragility of products and their heavy weight.

Today thermoses are used in different situations, so their volumes must be varied. When going for a walk with a child, it is enough to take a container with a volume of one glass (250 ml). For a short bike ride, a thermos containing 500 ml of liquid may be suitable. Traveling all day, 0.5 liters will not be enough: here you will need at least a liter or one and a half liter version. So, there are three types of volumes.

• Small... The filling capacity of models is from 250 ml to a liter. These include thermo mugs and sitotherms. You can take them with you for a walk.
• Average... Products with a volume of one or two liters. The best option for a hike. Thermoses fit easily into a backpack and contain enough liquid for a day trip.
• Large... Volume from 3 to 40 liters. Dimensional products are called thermal containers. They refer to desktop options, used at home for a large company. If necessary, they can be transported in the trunk of the car.

If your favorite thermos has begun to fail in something, you should find the cause and eliminate it. Today, manufacturers produce not only thermoses, but also a large number of components and accessories attached to them: from a simple rubber seal to a branded cover. In specialized stores, you can purchase the following types of components:

• silicone valve for thermos;
• replaceable screw cap with silicone gasket;
• replaceable sippy cover valve;
• silicone cork gasket;
• spare cup cover;
• silicone multifunctional insert.

The household thermos has been produced for over 100 years. During this time, the designers have actively worked on its appearance, and the designers have made their own innovative additions. Thanks to their efforts, unusual electric and smart thermoses were created. Let's talk about some of the design models.

Electric thermos by designer Adam Heiler. He decided to combine a compact electric kettle and a thermos in one model. As a result, I got a device that can warm up the contents of a thermos or brew fresh tea. Hayler added an electric heater to the Dewar flask, which is triggered when connected to the base. He worked on the design, and now the cap of the Thermo-Kettle liter container is also a teapot and the lid acts as a cup. The device has comfortable handles.

The smart thermos is designed by the designer Wenhua Zhang, it is user programmable and works in real time. The E-WAT device tells the owner when to take water. Athletes can use the thermos on the go as it has a non-spill dispenser and does not slip in the hand thanks to the carbon ribbing on the body.

Today even ordinary thermoses look unusually stylish. For example, you can choose a beautiful gift item or a cute item for a child. We offer a selection of thermoses with a pleasant design solution:

• a New Year's thermos, the lid of which is decorated with deer antlers;
• New Year's gift set;
• children's thermos toy "pink rabbit";
• a miniature fun product made of durable metal;
• thermo mug with an unusual design.

In the domestic market, it is easy to find a high-quality thermos for every taste and budget. You can choose a Russian-made product, German and American products have proven themselves well, Finnish models also leave good reviews. To make it easier to understand the range, we have compiled an overview of the most popular products for you.

• Dobrynya DO-1823. Domestic steel thermos with a wide mouth, designed for 1 and 2 dishes. Has a push-button valve to relieve pressure. The lid acts as a bowl.

• EMSA... The brand of the German company with a worldwide reputation. Gives a guarantee up to 5 years.

• Biostal NB-1000. A liter thermos made of steel, maintains the set temperature for up to 20 hours. The model is endowed with a push-button valve, a cup, and is distinguished by the strength of the case.

• Thermos SK-2010. It has a beautiful American retro design, but at the same time it is quite technological and modern. The product is compact, contains a volume of 1.2 liters, is durable and reliable.

• LaPlaya Strap. A miniature half-liter steel thermos keeps heat up to 6 hours. It is equipped with a sippy cup and a button-valve, which allows you to drink directly from the container.

• "Arctic-102"... Liter steel thermos, keeps heat up to 26 hours.

To date, different types of thermoses have been developed for different life situations. Before making a choice, you need to have an idea of ​​the tasks that he will have to solve:

• a thermo mug, a small children's thermos or a sitterm are enough for a walk with a child;
• for a one-day hike, a container of 1-1.5 liters is suitable, which is easy to place in a backpack;
• for a large company, home use or traveling by car, you can purchase a large product with a pump and a volume of 3-5 liters;
• if you have to carry drinks with you during the day, it is better to choose a thermos flask that fits in your pocket.

When choosing, you need to pay attention to the following points:

• for liquid, you should give preference to a thermos with the narrowest neck: it keeps the set temperature better;
• you should not buy a product "for growth": take a container of the required volume, since a flask that is not completely filled does not hold the temperature well;
• before buying, inspect levers, knobs, buttons: everything should work in standard mode;
• after removing the stopper, the flask should not exude an odor.

A correctly chosen thermos will be a good helper, not a problem.

The recommendations for using a thermos are very simple. They are contained in the instruction manual for the product, you just need to familiarize yourself with it. It is also advisable to take into account the following tips.

• Having purchased a thermos, you should arrange for him to be tested. Examine the product carefully. If there are no visible violations, fill it with boiling water, close it and leave it for the period stated by the manufacturer. If the liquid has cooled down by the appointed time, then the goods can be returned to the store.
• If everything is in order with the thermos, you need to prepare it for use. To do this, rinse the container and all parts thoroughly with warm water. The product can be assembled only after complete drying.
• During the operation of the thermos, it is necessary to monitor its cleanliness, wash the flask in time. After cooling, the unfinished liquid should be drained and the thermos should be thoroughly washed. Some flasks can trap unpleasant odors and transfer them to fresh drinks. Timely care, drying and ventilation will eliminate the problem.
• If the smell persists due to untimely care, you can try to eliminate it by rinsing with water and lemon juice or vinegar.

An experiment on which thermos retains heat better, and you can watch its results in the following video: