Two questions decide: does the container come back, and at what temperature must the product stay? Both work by frozen contents absorbing heat as they melt; the difference lies in the shell and the melting point.
| Gel pack | Eutectic plate | |
|---|---|---|
| Shell | Thin, flexible pouch | Rigid polyethylene, 34 mm at GEBHARDT |
| Melting point | Water-based, around 0 °C | -3, -14, -18, -21 °C at GEBHARDT |
| Suited to | One-way parcel | Container and vehicle returning daily |
In a one-way box the plate never comes back; a thin gel pack wraps around the product and going with the parcel is an accepted loss. In a container running the same route every day, the plate is frozen again and again. In a GEBHARDT Isotec container the plates slide into rails, and the freezer is kept at least 5 °C below the melting point.
With frozen goods the choice is clear: a gel that melts at 0 °C cannot hold product at -18 °C, which needs a -21 °C plate or dry ice.
