According to GEBHARDT's Isotec TBX paper, an Isotec TBX container used with eutectic plates keeps the cold chain unbroken for up to 24 hours. How much of that a particular route can use depends on the plate's melting point and number, the type of goods, the fill level, how well the container was pre-cooled, and how often and for how long the door is opened. The useful question is therefore: under my conditions, when do the goods reach their limit temperature?
Are an ice pack and a eutectic plate the same thing?. In everyday speech the small sizes are called ice packs; the industrial-size plate is properly called a eutectic plate. In GEBHARDT plates the outer shell is food-safe, durable polyethylene and the filling is a non-toxic mixture of salt and water. Unlike dry ice, a plate is used again and again, and it is chosen by melting point; the cap colour makes it easy to pick the right plate in the warehouse.
| Melting point | Cap colour | GEBHARDT recommended freezing |
|---|---|---|
| -3 °C | Red | -8 °C, 24 hours |
| -14 °C | Yellow | -19 °C, 24 hours |
| -18 °C | Green | -23 °C, 24 hours |
| -21 °C | Blue | -26 °C, 24 hours |
How long does a eutectic plate take to freeze?
GEBHARDT gives a freezing time of 8 to 24 hours depending on the cooling technology, and 15 to 21 hours depending on the freezer temperature. A plate with a -21 °C melting point, for example, freezes through in about 19 hours at -26 °C. The freezer must be at least 5 °C colder than the plate's melting point and the filling must be completely solid; a half-frozen plate does not deliver the expected cold, and every duration estimate assumes a fully frozen plate.
Placing the plates and pre-cooling
In the Isotec TBX, plates sit in galvanised steel slide rails at the top of the container or on an intermediate shelf reserved for plates; the rails take up to 6 plates. When freezing, leave an air gap between plates, because plates stacked flat on each other stay unfrozen in the middle; GEBHARDT freezing racks keep them spaced for this reason. The container itself is pre-cooled too: GEBHARDT recommends 12 to 20 hours, at 0-2 °C for fresh goods and between -21 and -25 °C for frozen goods.
A firm figure for your route comes from calculation. If you send Aris Makina the goods, volume, target temperature, transport time and ambient temperature, we work out the temperature curve together with GEBHARDT's thermal specialists, and the plate type and count follow from that calculation.
