When using passive temperature-controlled containers, it is necessary to pre-condition the components before packing. Generally, the components must be stabilized at specific temperatures. Typically, the outer containers and dunnage are held at room temperature. However, the refrigerants (such as gel packs or Phase Change Materials) need to be refrigerated (2°C to 8°C) and/or frozen (-20°C).
For large scale applications, the refrigerants will be received and conditioned as full pallets. It is not uncommon for a pallet to weigh between 1500 and 2000 lbs. Because of the large pallet mass, it will take a number of days for the entire pallet to stabilize with the environment. The outside refrigerants will come to temperature much faster than the refrigerants at the core of the pallet. The length of time to refrigerate or freeze is typically dependent on several factors, including freezer temperature, the total mass of the pallet, air flow and pallet stacking pattern.
Quick Tip: As a rule of thumb, it can take 1.5 to 2 weeks to freeze a pallet of refrigerants. To refrigerate a full pallet can take anywhere between 1 to 1.5 weeks. Because each freezer and refrigerator is unique, the exact time required will vary. Cryopak has conducted studies on this topic, the details of which are available upon request.