There are 40 hour and 72 hour disposable heat packs. Each has different peak time and temperature as well as activation time.
40 hour heat packs activate in approximately 40-50 minutes. It is the most popular type for shipping reptiles, amphibians, and insect shipping. The surface temperature is about 110 degrees at its peak. It releases a steady temperature and peaks between 17 and 19 hours.
72 hour heat packs activate slowly, up to 3 hours. Their maximum temperature is similar to the 40 hour heat pack. 72 hour shipping warmers reach their peak temperature in approximately 24 hours. 72 hour UniHeat shipping warmers are the best choice for 2 to 3 day shipments.
USING THE HEAT PACK
The idea of using heat packs for shipping is not to achieve the optimal temperature inside the box but to keep the temperature from falling so low that it causes the animal to be overly stressed or die.
If testing is needed before use, open the vacuum sealed package and roll in a layer of newspaper or place in a small space like a lunch bag or in your shirt or pants pocket and give it time to heat up. Don’t just place it on the table because you most likely won’t feel any heat released because the air volume surrounding the heat pack is much greater than the heat being released in the initial stage.
There are 2 sides to these disposable heat packs. The side with the red strips must always be exposed to air. Don’t lay the red striped side or tape it in a way that would obstruct the airflow into the perforated holes.
In a 1 cubic foot insulated box, the first heat pack will raise the temperature approximately 12-16 degrees. Each additional heat pack will raise the temperature about an additional 10 degrees. The temperature range of 60 to 75 degrees is very safe for most reptiles and amphibians.
If the temperature in the shipping box falls below 32 degrees Fahrenheit, the disposable heat pad may stop working because the water in the heat pack may freeze.
*Specially design for Pet Industry use* Takes the chill off winter shipping.