A cold-chain box does not state its own duration. The same box holds for a long time on a full, direct route and crosses its temperature limit much sooner on a half-filled multi-drop round. So always read an hour claim together with the temperature range the product has to stay in: without the range, the hours mean nothing.
The inputs that decide the duration are in the table; a test record should carry all of them.
| Input | What the record states |
|---|---|
| Product | Type, lot, loading temperature, packaging, box starting temperature |
| Load | Minimum and maximum fill, placement |
| Ambient | Hot and cold profile, position in the vehicle, dwell time |
| Coolant | Model, preparation, full solidification, placement |
| Lid | Number of openings and approximate open time |
| Measurement | Sensor positions, whether product or box air is measured, end value |
WHO's technical supplement on shipping containers for pharmaceuticals shows this layout plainly: the box is tested in a hot and a cold ambient profile, each with minimum and maximum load, and transport time runs from sealing the package to opening it in the recipient's cold store. A change in load, route, duration or components calls for requalification. The guide is for medicines, not food law, but it is one of the clearest statements of how a duration claim should be tested (WHO shipping container qualification supplement).
If sensors sit only next to the coolant, the result comes out optimistic. Points near the product, far from the coolant and affected by lid and wall need measuring too, with positions marked on a drawing; product temperature and box air are different measurements, so the record names the one the acceptance range belongs to.
A test that ends inside the range supports only the duration observed. If every value in a hypothetical eight-hour trace complies, it says nothing about hour ten, and it does not show the box would fail at hour eight either. Delay is not covered by adding arbitrary hours to the verified time: the route and expected delay are planned in advance and stay inside the tested configuration. If an untested delay happens, product and temperature data are assessed and the shipment is not released automatically.
GEBHARDT recommends freezing eutectic plates at least 5 °C below their melting point; if preparation differs, so does the box's duration. Send Aris Makina the route, product and target temperature and we obtain GEBHARDT's thermal calculation and pass it on; it gives the maximum transport time until the temperature limit is reached (GEBHARDT eutectic plates).
When the box, product, load, packaging, coolant, sensor position, route or delay changes, the old result is reviewed; the new configuration is numbered and its starting conditions, layout drawing, data file and acceptance decision are tied to one record. For monitoring see the cold-chain evidence guide, for packing ice-pack placement in EPS boxes.
