How to choose a thermal bag (refrigerator bag)?
Before switching to the choice of thermal bag, one needs to understand what kind of bags are called "thermal" and what are their differences with usual bags.
So, thermal bag is a bag that has well-defined thermal insulation* properties, that is, cold or heat badly pass through its walls, which allows for a long time** to maintain the desired temperature inside the bag. In the production of such a bag, special thermal insulation materials are used, which allow to significantly improve the thermal insulation properties compared to the usual bag.
* thermal insulation - the ability to maintain the desired temperature, that is, cold and heat - depending on the need. Unfortunately, many do not understand the principle of the thermal bag and mistakenly believes that the thermal bag works only as a refrigerator and can store only cold;
** after reading this definition, the logical question immediately appears: "for a long time" means how much? There is no clear criterion in this case, but the user of the thermal bag at other equal conditions must feel the significant difference in how long the desired temperature is stored inside the thermal bag and in inside the usual bag. If the difference is not significant - then there is a reason for doubt as to the quality and / or properties of such a thermal bag and the expediency of its use. It should be understood that the greater the difference between the temperature inside the bag and the temperature outside - the smaller is the time during which the thermal bag will be able to store the desired (different to the outside) temperature inside - this is the physics in its pure form and the quality of the bag doesn't play any role here.
Separately, it should be noted that even the best thermal bag under certain conditions may not keep the desired temperature inside - the reason for this is obvious - improper use of the thermal bag and failure to follow the recommendations for its use. Yes, before using any thermal bag (or otherwise, a refrigerator bag) there are clear requirements and instructions. Failure to comply with these requirements and instructions results in the bag losing its ability to perform its thermal insulation function.
There are three such basic rules:
1) The volume of the thermal bag should match (logically correlated) the volume of what you put in a thermal bag to keep the temperature.
If you need to keep the temperature of the frozen package in volume of 1 liter, then the volume of the thermal bag should not exceed 5 liters. Why so?
Here's an example: In a 50-liter thermal bag a 1-liter cooled bottle is placed. Accordingly, 50-1 = 49 liters of air is left in the thermoset, which will warm the bottle very quickly.
So, in order for the thermal bag to perform its thermal function effectively, a MINIMUM "empty" place should be inside the thermal bag. If you have a relatively large thermal bag and a lot of "empty" places in it - then you need to fill it with some filler, in the role of which is well suited paper, newspaper, fabric, etc.
2) You need to use "cold battery".
"Cold Battery" is a plastic container filled with helium or salt solution or a silicone container. Regardless of the type of "cold battery", the essence is the same - certain capacity, which in its physical nature has high heat capacity and the properties to cool or heat (depending on the need), after which it can store this low or high temperature for a long time, gradually giving heat or cold to other objects in a thermal bag, which in turn increases the time they are heated or cooled to the temperature that is outside of the thermal bag.
"Cold Batteries" are different, so depending on the type and size, you need to buy different quantity of them, it is important to read the instructions to them.
3) Do not open the bag without a need / open the bag for the shortest possible time.
It is logical that if you open the thermal bag, the air outside will "fall" inside the bag. Accordingly, after closing the bag this warm / cold air will heat / cool the contents of the bag. Therefore, in order to provide the best thermal effect of the thermal bag, it is desirable not to open at all. And if you have several separate objects in a thermal bag that you need to get at different times (eg, cooled water in the summer), then they are recommended to be isolated from each other. Ideally, for such cases, a thermal bag should consist of several separate departments.
Now let's return to the direct choice of thermal bags. In order to choose a thermal bag that will maximally satisfy your needs, you need to decide on the following parameters:
- Type of product - thermo bag or thermal backpack. It all depends on what you need.
- Size of the product. The size should be chosen according to the objective need. To take "with a stock" in the case of a thermal bag or a thermal backpack is a big mistake.
- The materials from which the product will be made. There is a large selection of materials from which a thermal bag can be made, but it is necessary to choose depending on the conditions in which it will be used.
- The level of thermal properties. Normally, even a slight increase in the thermal characteristics of the thermal bag requires significant financial costs for higher quality materials. Everyone decide for themselves what level of thermal properties they need and what the budget is.
When you have decided on all of these parameters, the most important question for you is how to distinguish the qualitative thermal bag from poor quality one.
In order to better orient, what kind of thermal bag is of sufficient quality and has a good level of thermal properties, it is necessary to understand the following:
- much of the heat / cold (depending on the need) "escapes" from the thermal bag through a variety of cracks - through seams, folds, lightning, etc;
- the thicker walls (at the same density) provide better thermal insulation;
- For thermal insulation of thermal bag, special thermal insulation materials must be used. Without them, the thermal properties of thermal bags are reduced in few times.
Accordingly, a qualitative thermal bag should have a minimum of joints, seams, separate parts and be as integral as possible. Also, the walls of the thermal bag should be fairly dense and thick, and one or more layers of the material from which the thermal bag is made should have a pronounced thermal property.
CITIZEN offers thermal bags and thermal backpacks with different levels of thermal insulation to meet the needs of all our customers. However, regardless of the price category, which includes a particular model of the thermal bag, we are trying to give our customers the maximum quality and thermal properties.