When testing packages for temperature assurance performance in a laboratory setting, using temperature profiles helps represent the expected temperatures that packages will experience in the field. A temperature profile is a sequence of time and temperature steps that can be programmed into an environmental chamber, allowing for repeatable tests to be run to examine this performance. Developing profiles to represent worst case temperature scenarios for each season is common practice. Rather than doing live shipments, the lab can simulate any season regardless of the current time of year.

Standard profiles are available from organizations such as ISTA (International Safe Transit Association), but the best practice is to create a profile specific to your actual planned shipping logistics. There are two main methods in which this can be accomplished; with a theoretical profile or a shipping lane mapping.

Theoretical Profile

First, create a theoretical profile via a detailed study of the logistical system, followed by assigning temperatures to each step in the shipment. Knowing the expected time durations and locations associated with the shipment allows for the searching of climate databases (such as NOAA’s National Center for Environmental Information) to choose worst case temperature conditions.

The advantage of this process is that it can be done simply with internet research, but has the disadvantage of not knowing how the logistical system’s temperatures relate to the environmental temperature. It is understood that an uncontrolled internal truck’s temperature will generally be higher than the ambient temperature outside of it in the summer due to heat pick-up from sunlight. 

Conversely, if a logistical step involves being at a sorting or cross-docking facility, the temperature will be near room temperature regardless of the external climate temperature. As a result, it can be difficult to determine how the climate temperatures will relate to temperatures the shipment will actually experience.

Shipping Lane Mapping

The other method of determining a custom temperature profile is through a lane mapping shipment (or series of shipments). In this process, actual shipments are conducted through routes and methods representative of the future logistical system, with temperature recorders included (such as Cryopak’s iMini USB PDF) to track the data.

The ability to measure actual temperatures in this process is an important advantage over the first method, but it also has its disadvantages.  Since a single shipment is being measured on a specific day, there is potential for the data to not capture the most extreme temperatures possible due to weather variability over time. Like any sampling activity, it is important to perform enough measurements that the result is significant and then apply logic to the results in order to remove outliers. 

Cryopak suggests doing at least three consecutive weekly shipments and timing them so that they occur during the hottest and coldest months of the year.  This results in enough data to create a profile.  Keep in mind that the overall project will take at least six months in order to capture both summer and winter conditions.