The most frequent question about Isotec is also the one most often answered badly: how many hours does it last. The GEBHARDT sentence is clear - an unbroken cold chain is held for up to 24 hours - but that is an upper bound and it depends on conditions. This page explains where the figure comes from and what changes it on your route.
Five factors that set the time
- The goods and their temperature at the moment the lid closes
- Fill level: a half-empty container holds more air to warm up
- Whether pre-cooling was done
- How often and how long the lid is opened along the way
- Route duration and ambient temperature
Any number of hours quoted without those five is a guess. The time for each route is calculated by thermal analysis from those inputs.
The system has three layers
The first layer is insulation: the walls keep the warehouse cold inside and the heat outside. The second is the cold store: eutectic plates in the rails under the lid draw heat at their melting temperature and feed the regime. The third is pre-cooling: container and goods are brought to the target temperature before departure.
Skip the third and the first two cannot do their job. A plate placed in a room-temperature container spends its first energy cooling the container rather than the goods.
How pre-cooling is done
- Move the container into the cold room or freezer 12-20 hours before the trip.
- Set the target temperature by regime: 0 to +2 °C for fresh goods, -21 to -25 °C for deep-freeze.
- Freeze the plates separately: the freezer must be at least 5 °C below the plate's melting point, with an air gap between plates.
- Do not leave the lid open longer than needed during loading; load in the cold room where possible.
Why the number of lid openings matters
Every opening lets cold air out and warm air in. If the lid opens ten times on a multi-stop delivery route, that route cannot be compared with the same load going to a single destination. The count can also be documented afterwards: GEBHARDT points to the 4smartlogistics solution, which records lid openings and the temperature profile along the way.
Where the exact figure comes from: thermal analysis
Together with GEBHARDT's engineers in Germany, Aris Makina carries out a separate thermal analysis for each application. It returns the number of plates needed for your goods and route, and the expected temperature profile. Its inputs are:
- The goods and the regime (fresh or frozen, target temperature)
- Route duration and number of stops
- Daily number of lid openings
- Fill level and the chosen size
- Ambient conditions
How to read the 24-hour statement
The GEBHARDT sentence describes a capability: in a properly set-up system the cold chain can stay unbroken for up to 24 hours. Reading it as a commitment valid for every trip would be wrong. What turns the figure into something about your route is the thermal analysis; what proves it afterwards is the temperature record.
