The Cold Chain

A chain is as strong as its weakest link. This is of particular relevance for a cold chain which preserves the integrity of a product by maintaining its temperature within a specific temperature range (2 to 8 degrees C is common). Many products, such as food, pharmaceuticals and some chemicals, can be damaged when not kept within a specific temperature range. Thus, supply chain integrity for temperature-sensitive products includes the additional requirements of proper packaging, temperature protection, and monitoring. For extremely high value cold chain shipments of small packages, even reefer services (refrigerated trailers or containers) is not fail safe, which in large part is fueling the growth of in-transit temperature monitoring. Attaching monitoring devices to the freight insures the recipient that the product integrity was maintained during transportation, and whenever a breach occurs, it helps identify the location along the supply chain where the breach of integrity took place (identification of the liability).

Reefers have become a crucial element of the cold chain as they offer a temperature controlled transport and storage unit, but are often too large for many types of cold chain shipments such as pharmaceutics. On the above figure, a cold chain is maintained over several transport activities, but with two potential breaches in its integrity. In the first case, it could involve the cargo being left exposed during the unloading process (or a reefer not connected to a power source during transshipment or the door left open for a too long time). In the second case, the product could have been stored in a refrigerated warehouse at a temperature below the product's storage specifications.

Due to the growth of temperature controlled shipments, a particular attention must be placed at identifying the locations, the equipment and the circumstances in which a breach in integrity can take place:

• Transportation issues. During transport, a malfunction (or an involuntary interruption of power) of the refrigeration equipment can in a couple of hours compromise the cold chain. Since the refrigeration equipment is designed to maintain a specific temperature level, a batch that was not previously cooled may place an undue stress on the equipment to the point that the temperature cannot be brought to the specified range. The reefer, due to wear and tear or defective equipment, may offer an improper cold storage environment, namely poor air circulation and defective insulation at seals (such as doors). Drivers may also voluntarily shut down the refrigeration unit to save on fuel costs, leave doors open for too long during deliveries or may be forced by local legislations to cut idling time.
• Transshipment and warehousing issues. During the loading, unloading or warehousing of a product, there are many potential situations where a cold chain can be compromised. For instance, a product can be left on the loading dock for an extended period or the refrigeration unit can be turned off during transshipment. Some warehouses can have poor temperature maintenance and control, while others do not have different temperature storage facilities so all the freight is stored at the same temperature.