Thermos are small appliances that are used to keep hot liquid hot and cold liquid cold for considerable duration of time. Thermos or vacuum flask are very useful appliance when you are traveling and want hot cup of coffee. A vacuum flask has very good capacity to hold extremely cold liquids like liquid nitrogen for a considerable length of time. The boiling point of liquid nitrogen is 77K compared to a room temperature of about 300K. You can hold liquid nitrogen for about a day without even a cover on the flask. There are many types of thermos flask available, if you are looking for a best thermos in India, this article will help you in this regard.
How Does Thermos Flask work
A thermos does not allow heat transfer by any of the three ways like radiation, conduction or convection that heat can travel. The silver coating on the inner surface of the vacuum flask prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask by conduction. The case surrounding the thermos flask provides additional insulation.
A thermos is very much like a super-insulated jug. Though there are many types of thermos available today, but all of them have an inner chamber and an outer plastic or metal case separated by two layers of glass with a vacuum in between. The glass is usually lined with a reflective metal layer. Unbreakable flasks do away with the glass. Instead, they have 2 layers of stainless steel with a vacuum and a reflecting layer in between them. There’s also a tight, screw-down stopper on the top.
The above features that we mentioned above prevent virtually all heat transfer by either conduction, convection, or radiation. The vacuum prevents conduction. The tight stopper prevents air from entering or leaving the flask, so convection isn’t possible either. What about radiation? When infrared radiation tries to leave the hot liquid, the reflective lining of the inner chamber reflects it straight back in again. There’s virtually no way heat can escape from a vacuum flask and a hot drink stored inside will stay steaming hot for many hours.
Heat Blocking at Vacuum Flask Top
The blocking of heat transfer into the liquid nitrogen from the top of a vacuum flask involves the insulating properties of gases and the ideal gas law. The gas above the liquid surface can be presumed to be dry nitrogen. When the ideal gas law is applied at approximately constant atmospheric pressure. So the cold nitrogen above the liquid occupies about one-fourth of the space it would occupy in the surrounding room- temperature air. The dry nitrogen at about four times normal density forms an effective insulating “stopper” on top of the liquid.
Choosing The Right Thermos
Thermos are comes in both stainless steel and plastic with stainless steel being more expensive compare to plastic. Even though stainless steel initially costs more, it will give you much better value for your money. Plastic mugs can break when dropped and they don’t keep your coffee or tea hot nearly as long as the stainless mugs. While choosing a vacuum flask, it is important that you buy according to your need. A vacuum or thermos flask is used to keep hot beverages hot and cold beverages cold for many hours. There are different types and functions of a thermos flask, depending on your need you should pick an appropriate thermos flask.
You can expect much better performance from a stainless steel thermos keeping your coffee or tea hot for more than two hours. If you are looking for the very best vacuum flask in India to keep your favorite beverage hot or cold longer, look for a mug with stainless steel double wall insulation. Thermos flask come in a variety of volume sizes. If you only for single person who drinks a small amount, consider buying a small flask of 500ml. On the other hand, if you want a large amount of coffee or tea to drink, consider a larger 1 litre or 2 litre thermos flask. The advantage of a travel mug that fits a cup holder is you don’t have to hold onto it. Just make sure the dimensions of the mug will fit your holder.
Many people want to make their coffee on the go instead of just drinking it. There are thermos that you can buy that have infusers that you can use so you can put the tea bags directly into the mug along with the hot water. The vacuum insulation these mugs usually have will keep the tea hot for hours. This is perfect for green tea lovers since brewing the tea for a long time doesn’t seem to affect the flavor in a bad way at all. You could even make a mug full of cold brew iced tea in these mugs on the go. Many travel mugs aren’t dishwasher-safe, so look for wide openings and easy-to-disassemble lids, without lots of nooks and crannies, that will be easiest to wash thoroughly.
Thermos also comes in different color and design. You won’t have to settle on plain white or gray anymore. You can even choose your favorite sports team for a travel mug. Don’t sacrifice performance for style though. A sports team travel mug may look great but if it leaks and doesn’t keep the drinks hot or cold it’s not worth it and you’ll end up buying something else.
Benefits of Using Thermos Flask
So many people today are so busy and do not have much time for cooking and preparing breakfast. They are always on the go now more than ever and having a way to safely transport coffee, tea and other hot beverages makes the trip much more enjoyable. Thermos are popular with commuters, office workers, and many people who work in an industry where they are driving such as taxi driver, bus driver, pilot, and other types of jobs where having a regular cup of coffee or tea isn’t very safe. Here are some of the benefits of using thermos flask.
- Vacuum flask are useful during winters, when many people have the urge to drink hot coffee or tea. Tea and Coffee tend to change taste when reheated. Therefore, in order to savour its original taste, you can use a thermos flask. These thermos flasks are insulated and are of great help.
- Thermos are often used during traveling. Thermos flasks are made in such that the chances of spilling liquids are minimized.
- Apart from keeping things hot, they are also used for keeping cold water, drinks and cold coffee cold for several hours.