When you are looking around for different cooler boxes, a particularly effective ice box is one that is insulated with at least 2.5 cm of PU foam on the walls and bottom of the box. The lid of the box should have even more insulation as this is typically exposed to more sunlight and sufferers from a greater heating effect than the sides. Aside of this insulation, the outer shell of ice boxes has typically been treated to resist ultra violet rays, as well as being able to resist scratches and the kind of color deterioration that comes with age and use.
There is a range of insulated boxes produced as shipping boxes. These cooler boxes are specifically designed to transport meat, poultry, fish, chemicals, tropical fish and other items that need to be sensitively shipped in temperature controlled conditions. There are many kinds of insulation used, depending on the specific requirements. These insulation materials may be bubble wrap, foamed plastic, thermal blankets or even corrugated cardboard. The one thing these all have in common is their ability to be able to trap the air and utilize this trapped air for insulation properties.
Insulated boxes that are used for shipping various items vary in size and shape depending on the size and shape of the items that are transported. Generally, however, we are looking at an oblong box or earning heights. As an example, some suppliers market a mackerel box which is an extra-long cooler suitable for storing mackerel, king fish and tuna. The external shell is made from tough polyethylene in rugged finish. Although made of lightweight materials, these mackerel boxes are usually particularly durable, made to a high specification for commercial use.
Mackerel boxes come in various sizes. Common sizes are boxes with 100 liter, 210 liter, 260 liter and 700 liter capacity. The empty weight of these boxes varies with size and can be as little as 14 kg while a 700 liter box can weigh as much as 50 kg. When it comes to the average length of a mackerel box, they are much longer than a standard box with the same capacity. For example, a 100 liter mackerel box from one manufacturer is 136cm long, while the 100 liter standard cooler is only 92cm long.
When it comes to the thickness of the walls you can imagine just how much CFC-free PU foam insulation has been pumped into each of these mackerel boxes: the walls of a typical high quality 100 liter box has 30 to 40 mm thick walls; the lid is usually extra thick, measuring 50 to 70 mm, allowing for a reasonable amount of insulation to be pumped in between the two shells. The walls of larger mackerel ice box usually are even thicker, with the walls measuring 70 to 80 mm thick and the lid being 90 to 100 mm thick. That is a lot of insulation so it is seriously surprising that any ice stored in these mackerel boxes may stay viable for up to 7 days.