How long passive cooling lasts cannot be stated without product, load and route data. Measure its limit in the field.
Define the use case
Record product, load quantity, container and coolant configuration, preparation and starting conditions.
Include route conditions in the trial. Track actual duration, dwell, ambient conditions and lid-opening frequency in a representative test. Take product readings using a defined method and sensor location.
Compare results under the same configuration with the critical acceptance range in product instructions or the quality plan. Do not substitute catalogue duration for field evidence.
With the three numbers in hand the right body is easier to choose. The sizes and plate arrangements on the passive side are listed one by one in the GEBHARDT catalogue.
Document the limit decision. Add tested conditions, loading diagram, temperature record, observed excursion and approver to the report.
A longer route, different season, load or opening pattern may change test coverage; assess the differences.
Compare with an active system. If continuous control or a route longer than demonstrated is needed, assess an active system, transfer point or another approved option and requalify it.
If safe transport against product requirements is not demonstrated, do not rely on a passive container as the only control.