How Does a Cool Box Work?

Icy cold in Petromax format

As a proven outdoor chef always looking for an adventure nobody can fool you: You can light a fire in your sleep, you skilfully heat up the Dutch Oven to the right temperature, and single-handedly prepare the food. Still, no matter if menu from the grill, steak at base camp, or freshly caught fish at mooring: You always need to face the challenge of cooling your food in nature for several days on end. For that purpose, Petromax provides you with maximum independence with its kx-series of ultra-passive Cool Boxes. Here you can find out about which kinds of cool boxes there are and what makes Petromax Cool Boxes so strong and what extra functions they have to offer.

What Cool Boxes are there in the first place?

The choice among cool boxes is large and the preconditions, as well as the fields of applications, are diverse: at first, thermoelectric cool boxes, absorption cool boxes, or compressor cool boxes seem to be ideal for camping, caravanning, etc. Even though they reach low temperatures within a short time they can only maintain it by means of a power source or gas supply. For you, that means a certain level of comfort on the one hand, however, on the other hand also the dependency on energy sources together with operating costs and operating noise. After all, this restricts you in the way of your adventures under the open sky. Passive Cool Boxes are the only alternative cooling option that works self-sufficient and make you completely independent. Running solely with ice or cold packs this kind of cooling system ensures for the preservation of your food and beverages – without external energy, operation noise or cost, or electricity prone to failure.

Strong performance: Function of a passive Cool Box

Also, among passive cool boxes, there is a vast choice. For the as simple as the clever principle of indirect cooling with ice there are two essential points: product processing and the insulating layer. As in a house, it makes a difference if the walls are thick or thin or if they are lined with thin or thick insulation. The right balance ensures preferably long-lasting temperature stability on the inside. At this exact point the construction of the Petromax ultra-passive Cool Boxes starts:


The corpus of the Petromax Cool Box consists of durable polyethylene. All parts are double-walled, made in one piece, and convince with a constant wall thickness. The core of the kx Cool Boxes is the insulating layer. The pressure-induced PU foam enters even the smallest cavity and forms – in combination with the double-walled corpus – an efficient wall of cold. The high-performance insulating foam has a very low thermal conductivity and with at least 45 mm thickness it also has very impressive strength. For that reason, Petromax Cool Boxes can keep ice cool and the inside temperature at a constant level for up to 12 days. That way you are perfectly prepared with your strong support for independent cooling.

Tips for an optimal cooling performance

  • Cooldown the Cool Box before use in a cold room or with ice
  • Only stock with pre-cooled beverages or food
  • At best use large blocks of ice in one piece
  • Always place dry ice, cold packs or ice on top, as cold sinks downwards
  • Open purposeful and seldom
  • When on the way store the box at a cool, shady place and out of direct sunlight
  • Store and transport only in an upright position

Advantages of a Petromax Cool Box

In addition to the extreme cooling time the Petromax Cool Box has even more to offer: With the kx25 and kx50 you can choose between two models, that with either 25 l or 50 l filling volume provides for enough reserve for long trips in the open. Also, the internal dimensions have been designed in such a way that you can transport common 1 l PET bottles (or 1.5 l for the kx50) in an upright position. The kx50 can contain up to 20 x 1 l bottles or 70 x 0.33 l bottles respectively. Here you can find out more about the filling volumes and the recommended ice ratio.

Another advantage offers the integrated draining system. With that, you can easily drain melting water when on the way and refill ice without having to clear out your provisions. Furthermore, this way your Petromax Cool Box can be cleaned easily after your trip into nature. Apart from that, your Petromax Cool Box has been thus designed that you have a variety of useful functions at hand.

Additional functions of the Petromax Cool Box:

  • Lid with a non-slip surface for use as a seat or raised stand
  • Guide for lashing straps for closed transport
  • Reinforced locking plates for additional securing via U-lock
  • Non-slip rubber locks (one-handed operation)
  • Ergonomic carrying handles with additional lashing eyelets for secure opening/closing during transport
  • Non-slip rubber feet for a secure stand and circulation of air on the bottom side

Conclusion: Indispensable part of your independent outdoor kitchen

Extreme cooling time, protection, and preservation of food and beverages for days on end, seat and stand for fishing, secure transports on the loading area or the boat: The Petromax Cool Box has much to offer and delivers on its promises. With this box, your outdoor experience will become more original and you will be more independent. Pack your stuff and provisions and from now on plan longer breaks away from the hustle and bustle of everyday life.

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