Plastic Vacuum Flasks
for perfect enjoyment
Helios plastic thermos jugs are made of robust plastic material and have an insulating insert - either made of glass or stainless steel.
Helios offers a wide variety of plastic vacuum flasks - they are available in different sizes, designs and colors and are ideal for use at home, in the office or outside.
Why does a vacuum flask keep heat so well?
The interior of the vessel contains double-walled glass insert. In addition, the glass walls are coated with a thin layer of real silver. This reflects the heat radiated by the hot beverage, retaining it in the interior of the glass flask. Furthermore, the cavity inside the double-walled flasks is evacuated, i.e. the air has been extracted. So there are no air molecules which could carry away the heat – simply clever.
Only the perfect interplay of these factors permits heat retention at such a high professional level:
- Reflective coating of the glass flask, prevents heat radiation
- Evacuation of the glass flask, prevents convection
Is there a difference in the heat retention of small and large vacuum flasks?
Yes, there is. Compared to their external volume, small thermos flasks with a capacity of 0.3 or 0.6 l contain less high-energy (therefore hot) liquid. In contrast, large thermos flasks, with a capacity of 1.5 l or above, retain the heat better. Because in this case the external volume in relation to the hot contents is more favourable for optimum heat retention. But there’s no need to be concerned; our small coffee and tea flasks are also “heat retention experts”. So in a 0.3 l product from Helios, you can keep your drinks at a temperature of at least 60° over six hours. Still perfect for drinking.
Here an overview of the heat retention of a Helios thermos vessel:
- Contents 0.3 l – 60° after 6 hours
- Contents 1.0 l – 75° after 6 hours
- Contents 1.5 l – 78° after 6 hours
And because we are absolutely sure that we produce only outstanding quality, we even give a 5-year guarantee on the heat retention of our tea and coffee jugs.
How can I clean my vacuum flask?
There are a number of possible ways to ideally clean your thermos flask. The best option is undoubtedly to own a dishwasher-safe thermos flask from Helios. Because this proven professional quality can be cleaned in every dishwasher – even in professional dishwashers in canteens and hospitals! The products in the dishwasher-safe series from Helios are protected from dishwater with a very special “Santoprene seal” – a unique production process.
But of course you can also wash our products quite normally with water. Simply rinse the vacuum jug with clear water after use and let it dry thoroughly. However, it can happen that after some time in use, discoloration occurs in the interior of the vessel. But there is a solution to this too: the Helios cleaning tabs. Fill the tea or coffee jug with hot water and add a Helios cleaning tab. Within just 1 – 2 hours, the inner flask is spick and span again.
Are there special products for outdoor use or to go?
Yes, of course. If you want to take a vacuum flask along when you are outside, it is particularly important that it is, and stays, leak proof. And you can depend on this with our models. Our internal tests for vacuum flasks (DIN 12546-1) ensure that the function and leak tightness remain guaranteed for the entire outdoor stay.
Are vacuum flasks available with large openings?
Yes, we offer those at Helios. We call these products wide-necked flasks – as they have a wide opening for filling (neck). The standard diameter for a thermos flask is approx. 4.0 cm. This is more than enough for filling it comfortably with coffee or tea. But sometimes a larger opening is useful, for example for additional tea strainer or to allow the flask to be cleaned more easily afterwards. This is why we invented our wide-necked flasks series. With an opening of approx. 8.0 cm, it is even possible to insert your hand into the inside of these products.
Can I replace the glass in a vacuum flask by myself?
Yes, that is possible. We at Helios offer spare parts for all our products – and continue to do so for many years. If the glass in the interior does get broken, we offer extensive replacement parts. In these cases, we also recommend replacing the sealing ring at the same time. Under the following link you will find exact video instructions of how you can replace the glass yourself in your thermos jug: https://www.youtube.com/watch?v=pEhKCKsLf0Q
For vacuum flasks: https://www.youtube.com/watch?v=qULVz7pea6g
Please note that it is not possible to replace the glass in dishwasher-safe vacuum jugs because of to the sealing.
Are there special vacuum flasks for babies or children?
As a matter of principle, all our products can be used for babies or children – they have already been tested for food safety. Of course vacuum flasks made of plastic or stainless steel are particularly well suited as they are especially convenient for outside. Here, we recommend our products Helios Elegance and Helios Active.
What is a Dewar flask?
All insulated vessels contain what are known as Dewar flasks. The name derives from the inventor, the Scottish physicist Sir James Dewar. We call them simply double-walled insert. A flask of this kind is always constructed as follows:
- A double-walled construction made of glass or metal
- The interior space is evacuated, i.e. the air is extracted from the space between the walls
- Silvered inner surfaces
As a result of this structure, the possible heat transfer - specifically heat radiation, heat conducting and heat convection - is reduced to the greatest possible extent.
- Reduction of heat radiation by means of metalisation of the inner surface of the Dewar flask. The energy is reflected by the silvering.
- Reduction of heat convection. Because the space between the vessels is a vacuum, no molecules are present which could act as heat conductors.
- Reduction of heat conducting by means of long conductor routes. Because the glass or metal walls are not connected, the thermal energy along the inner wall has to travel a long way to reach the outer wall.
All insulated jugs, thermos flasks and insulated vessels still work on this principle today – regardless of whether the inner flask is made of glass or metal.
