Countless temperature-sensitive products are shipped everyday using cold chain packaging systems. While these systems were designed and tested to protect their cargo during transit, many components need to be prepared and assembled under specific conditions in order to work properly. For example, a prescribed number of refrigerants are usually cooled or frozen to a specific temperature and then assembled in a cold chain packout based on a designed protocol, which are established depending on seasonal temperatures. Inadequate selection of protocols, conditioning of refrigerants and assembly can lead to lower performance and ultimately jeopardize the products integrity. The reproducibility of cold chain packaging assembly is an important factor that has a direct impact on its performance over time.
Here’s a list of actions that can be carried out to increase process repeatability.
Cold Chain Packaging Pre-Qualification Results Analysis
Every tested cold chain packaging comes with a report that includes a description of the solution, the testing methodology, the test requirements, the test results and the protocol to follow when preparing and assembling the systems. Among the test results are repeatability indicators (statistics), which are given by each tested sample Mean and Standard Deviation. These statistics are very useful to determine the following:
What the pre-qualified shipping system average inner temperature is during transit for each season it was tested against.
How much inner temperature variances are recorded across each shipment when using the pre-qualified shipping system.
Repeatable cold chain packaging systems will have a Mean and Standard Deviation that are very similar, if not identical. Tested solutions that show a large difference in both statistics should be avoided.
Note: The sample’s minimum and maximum temperatures are not indicators of repeatability but will tell you if the shipping system inner temperature remained within the required temperature range.
Refrigerant Conditioning Process
Refrigerants used in qualified cold chain packaging solutions are conditioned using commercial freezers and refrigerators. These equipment can have various shapes and specifications from one manufacturer to another. As an example, when looking at two different freezer models from two different brands, although seemingly identical, there can be a difference of ±2.0°C temperature uniformity. A significant difference that can affect the speed and uniformity at which gel packs are frozen, leading to uneven refrigerant freezing, a common mistake operators make during the conditioning process.
Here’s how to avoid this mistake:
Conduct temperature mappings on each refrigerators, freezers, and ambient conditioning rooms and equipment to establish their adequacy for conditioning refrigerants at the right temperature. Note: that for most cases, equipment qualification (IOPQ) is required by Health Canada and provides more assurance in the equipment performance output.
Continuously monitor every equipment involved in the conditioning of refrigerants to verify that temperatures aren't fluctuating outside acceptable limits.
Conduct preventive maintenance on every equipment involved in the conditioning of refrigerants to avoid failures and temperature drifts over time.
As the season changes, so does the shipping system assembly protocols. Cold chain packaging solutions are tested against shipping route profiles that are based on the carrier's shipping lanes, the carrier’s ability to maintain good temperature control, the outdoor temperatures and the exposure of solar radiations. These profiles are usually summarized into summer, winter, and fall/spring test scenarios. While summer and winter will include extreme temperatures (the highest and lowest temperatures recorded over the year), the fall/spring temperatures will not include such peaks. Because of these temperature differences, the required amount of refrigerant latent heat will largely differ for each season. Hence, the importance of using the right tested design temperature profile. For example, summer designs include a large amount of frozen refrigerants to keep internal temperatures within acceptable limits. If this design was used during the winter season, it would likely reach subzero temperatures and harm the transported products. It is therefore essential to ensure that assembly protocols are matching the current seasons and that refrigerants are prepared and conditioned by following the same protocols.
Cold Chain Packaging Materials
Knowing where Cold Chain packaging materials are coming from and how consistent the product quality is, can make a big difference in the overall performance of shipping systems. Vendor qualification and audit processes are good ways to ensure that the necessary operational and quality infrastructure are delivered consistently every time. Also, having an inspection process (Batch Sampling) upon the receipt of critical parts can help identify non-compliant products. Buying locally can also reduce supply chain disruption events and improve in-time deliveries. However, if buying locally is not an option, having safety stock at a nearby storage facility can help mitigate supply chain issues.
Cold Chain Packaging Operators and Environments
For the most part, companies that use Cold Chain packaging methods have a dedicated team of trained staff to handle, condition, assemble and send shipping systems. The “packers” can assemble a significant number of shipping systems per day, with a variety of products to protect. These products can have different temperature requirements with different Cold Chain packaging protocols to use. Needless to say, “packers” must be vigilant and well instructed in order to assemble parts efficiently.
Here’s a few things “packers” must be aware of:
Current Weather Conditions
Assembly Protocols (usually determined by the company’s QPIC or the SME)
State of the refrigerant’s conditions (ready to use or “Under Conditioning”)
Product temperature requirements and destination
Assembly environmental conditions (room temperature, relative humidity, dust, and vibrations).
All these listed factors are continuously changing and must be well supervised. To avoid assembly mistakes, it is essential to have a good training program with dedicated personnel, a well organized assembly environment and clear assembly protocols. Process repeatability is critical to maintain cold chain packaging solutions at a high reliability level and to ensure that every assembled system is holding up to its expectations.