A box average can conceal a cold spot next to a product. Assess freezing risk with the actual product, divider and cold-source layout.
Measure the field layout
Mark cold sources, barriers, products and logger on the packing diagram. Place a sensor at product level at the highest-risk point nearest the cold source; if using a second representative point, record its location and purpose. A sensor touching a pack may not represent product conditions.
Run a trial with the real load and work instructions. Record box model, pack preparation, void fill, openings and sensor positions together for each run. Review product-level records rather than relying on the average alone.
If an excursion occurs, segregate the product and retain the graph, timestamps, box ID and loading diagram. Obtain a written, product-specific decision from the manufacturer or authorised quality lead.