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How do heat packs work?

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  • How do heat packs work?

    I've read the description and it states it warms up to 100-110 fahrenheit/43.3 Celsius wouldn't that be cooking whatever you are shipping?
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  • #2
    1. You don't put the heat pack right next to the fish, so the temperature will be a little lower by the time the heat reaches the fish and makes its way through the bag
    2. Water has a high specific heat capacity, so it takes a lot of thermal energy to raise the temperature
    3. A lot of heat is lost through the box, rather than being absorbed by the water, especially if it's cold outside

    As for how the heat packs actually produce heat, it's an exothermic chemical reaction that starts once it is exposed to air (as it needs oxygen to proceed) and proceeds very slowly, so it takes awhile for the reaction to reach equilibrium and for heat to stop being produced.

    Hope this helps


    • #3
      Most packs use the oxidation of iron to generate their heat. As kinezumi89 said, it is best to have something between the pack and the bag of what ever you are shipping.
      The old that is strong, does not wither.


      • #4
        Iron (III) oxide, the product of iron oxidation, is the proper term for rust


        • #5
          How do heat packs work?

          Its been so hard not to be smartypants...
          It does not matter if you are right or wrong...
          As long as you learn and Keep Moving Forward!



          • #6
            When using heat packs to ship livestock, you want UniHeat packs, not the hand warmers. There are some hand warmers that can last up to 10 hours, but they get to degrees up to 156 F. That will basically cook everything then die once its lifespan runs out and the livestock will get cold from the external temperatures.

            Pretty much a death sentence using those type of heat packs, so you want the ones designed for live animal shipping.