Are your chamber tests mis-guiding you?

Are your chamber tests mis-guiding you?

Shipping temperature-sensitive goods like food and medicines requires meticulous planning and packaging. Many shippers turn to chamber testing as a means to validate their packaging strategies, but this approach often falls short of reflecting the real challenges that shipments face during transit. In this blog post, we'll explore the limitations of relying solely on chamber tests and emphasize the critical role that real-world data plays in developing effective coolant strategies for small parcel shipments.

In chamber tests, conditions are perfectly controlled

When a chamber test is run, boxes are:

  • Suspended in a chamber
  • Meticulously packed to spec
  • Cycled through extremely precise temperatures
  • Kept still for the entire test

This is great for ensuring a shipment can perform in a very precise scenario, but it doesn’t reflect the real world.

In the real world, conditions are chaotic:

  1. Boxes sit on hot surfaces like asphalt, truck beds and other shipments - each conducting heat differently.
  2. Boxes are rotated and shaken during transport causing goods to shift within the box, impacting temperature distribution.
  3. Dry ice can be partially sublimated before packing. Even when 10 lb. are supposed to go in the box, in reality, some might get 8 or 9 lb.
  4. The items in the box will vary. The initial product temperature, product weight, and product placement will vary. Each of these factors impacting thermal performance.
  5. Not all insulation panels are the same. The insulation will have different densities, compressions, and gaps between the panels - each factor impacting how much heat can get into the box.

An example

Below we show a typical test performed by a packaging supplier.  The cooler broke threshold at 60 hours with an average ambient temperature of 80F.

It looks like the shipper received some good news…with this single data point, they can now confidently say their packout held temperature comfortably beyond the 2-day journey.

However, these results don’t hold up in the real-world. Using Keep it Cool’s single-use temperature loggers, we can collect data on hundreds of real-world shipments that underwent the chaotic conditions described above. Below, you can see a graph of the temperature at delivery for shipments that had the same packout and average ambient temperatures as the chamber test above. The only difference was that these were live shipments to real customers.

In the above bar chart, we saw a sample size of 96 shipments that faced an average ambient temperature of 80F-matching the conditions of our chamber test.  Of those 96, 14 of them arrived at or above threshold temp of 41F.

If this shipper had relied on this chamber test alone, ~15% of shipments would have arrived at an unsafe food temperature; leading to unsatisfied customers churning or requiring a refund/reship.

When do chamber tests make sense?

Chamber tests remain valuable for controlled comparisons and single-variable assessments. For example, if you want to compare two identical shipments with different types of insulation. However, they must be used as a complementary tool rather than the sole determinant of coolant strategies. Relying solely on chamber tests can lead to unrealistic expectations and inadequate packaging strategies.

How to get started with real-world testing?

Want to see how your packaging performs in the real world? Set up a demo using link below and we will walk you through deploying sensors in your shipments and how to develop a coolant strategy that accounts for the real-world factors at play.

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Book 15-minutes with Patrick, our founder and CEO.