Coolers, Ice, and your Samples

Below is some data on how long a cooler may last depending on how you prepare it.?Nothing that you probably didn’t already suspect but this shows that a little effort on the packing side could make the difference in the samples arriving within the temperature range or not

To pre-chill or not?

We took two standard Coleman coolers with four one-liter containers of water, packed them with 20 pounds of ice, then placed them in the storage building where it was normally 80° to 85° F (27°-29° C). ?The time to reach 6° C was as follows:

Prechilled samples – 62.75 hours

Room temperature samples – 56.75 hours

So prechilling the samples and cooler increased the time they remained below 6° F by 6 hours / 10%.

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More Ice is Better!

Again, we took two standard Coleman coolers both with three one-liter containers of water.?One cooler was packed with 20 pounds of ice and one packed with 30 pounds of ice.?The two coolers were stored in a room that was 68° to 69° F (20° C).?The times to reach 6 degrees C were:

20 pounds of ice lasted 91 hours (3.75 days)

30 pounds of ice lasted 123.5 hours (5.15 days)?

So, a 50% increase in ice resulted in the cooler lasting 36% longer.

Ambient Temperature Matters!

If we look at the two datasets above, we see a cooler with 20 pounds of ice lasted over 90 hours if it was 68° to 69° F (20° C) but only lasted approximately 60 hours if the ambient temperature was 80° to 85° F (27°-29° C).?But…..it is important to remember, that your cooler may be:

·???????In a FedEx truck in the sun with no air conditioning

·???????Setting on a tarmac at 150° F

·???????A sealed shipping container setting on the tarmac.

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In Summary

It is best to pre-chill, more ice is better than less ice, and ambient temperatures matter (especially in the South in August).