Preconditioning
Preconditioning brings cooling elements and, where applicable, other packaging components to a defined initial thermal state before packing. Temperature, duration and loading method are specified for this purpose. Depending on the system, preparation includes freezing, chilling, warming or an additional tempering stage.
Which process variables matter?
- The temperature of the conditioning equipment and the time actually required to achieve the intended state.
- Spacing, stack height and air circulation: a densely packed load may condition differently from individually spaced elements.
- The permitted time between removal and packing and, where applicable, deliberate tempering after freezing.
Is a suitable surface temperature sufficient?
No. The surface and core can be in different states. With PCMs, the solid and liquid fractions can also change without a marked temperature change. The state of charge therefore cannot be read from a thermometer alone. Approved packing instructions describe the verified process; general freezing times cannot be transferred to every format.
Related terms: Packing Instructions · Gel Pack
Technical references:
WHO: Qualification of shipping containers