Let’s briefly the thermos, the container of choice for hot drinks.
The thermos used to lug around a hot drink (coffee, tea or herbal tea is generally discouraged) always nice at the top if the weather is not too hot, which is essential when you expect cold because the altitude or weather uncertain. Preferable metal ones to those in plastic weigh and clutter less and can withstand more shocks. A thermos from 0.33 provides two to three cups, evaluated according to your needs, there are also by 0.5-0.75-1lt. overall dimensions greater than a bottle of the same capacity. Many have a thermos stopper provided with exit holes to pour the liquid without unscrewing the cap, useful for restricting beverage cooling and to avoid having to place the cap and prevent it from getting dirty or regrettably rolls downhill.
In the second picture we see the plugs which seal the opening of the thermos, under the “nut” that can perform the function of glass. Identifies:
1-spout (thermos left) and chinks (thermos right) for leakage;
2-center button to open the leakage (pictured are both pressed);
3-ring (around the central button) button to close the leaking (pictured are both raised, ready to be pressed)
To fill (and clean up) we’re still going to need to also remove the thermos lid itself. A good thermos, if filled with hot liquid or nearly so and if not open except for the hole to pour the drink mentioned above, should keep warm fluid containing all day (or nearly so, according to the external temperature met).
To get an idea of the weight of the thermos flask and see weights. In addition the thermos flask and cups also thermic, of various types, too.
Last note “technique”: water bottles & thermos hermetically sealed as they suffer decompression effect that happens whenever we bring in fee (at atmospheric pressure) an airtight container sealed to lower altitude (and higher atmospheric pressure). This effect is particularly evident in the case of soft containers or plastic bags sealed as those for cheese, salads, chips, etc. which brought high-flying swell like balloons as the balance between internal and external pressure exists when were sealed fails: internal pressure is greater than the external thrust of indoor air is no longer adequately countered by that of the outside air resulting in bloating the container. In water bottles filled at low altitude the same phenomenon, with the result that for those in metal or fiberglass opening water snorts and squirts out, especially if too full and open quickly, while plastic ones from cyclist can even swell and warp. The same happens in thermos though generally realize less, especially with the caps that we don’t have to unscrew to pour the liquid. If on the other hand we fill the bottles at high altitude, opening them downstream we should feel some kind of sucks (the opposite effect) or, for those in plastic, even should we see them “collapse” (is a test that I have yet to do). To expand or collapse is only the amount of air left in the bottle (the water keeps constant volume) and the effect is more or less evident depending on the pressure and/or share overhang.
It is also the reason why within the spacesuits for spacewalks, while using outer space, atmospheric pressure is kept very low (otherwise would tend to swell even if in reality there is a knitted fabric that is used to counteract this effect).