With a plate freezer, temperature comes first and capacity second. GEBHARDT requires the freezing temperature to be at least 5 °C below the plate's melting point: -8 °C for a -3 °C plate, -26 °C or colder for a -21 °C plate. That figure has to hold with the cabinet full of plates and the door being opened, not just when it stands empty; if it does not, the plate freezes on the outside and stays liquid inside.
| Criterion | Why it matters |
|---|---|
| Internal temperature under load | At least 5 °C below the melting point |
| Air circulation | Freezing through to the core of the plate |
| Gap between plates | Cold air reaches every surface |
| Door traffic and recovery | Temperature returns after each opening |
Capacity is worked out by the rack. GEBHARDT freezing racks keep the plates spaced apart and take 72 or 144 plates; for 480 x 280 mm plates the 72-plate rack measures 860 x 600 x 1625 mm and the 144-plate rack 1165 x 985 x 1600 mm, which decides whether it fits the cabinet at all. Since the Isotec TBX slide rails hold up to 6 plates, one 72-plate rack freezes the full set for 12 containers. Freezing takes 15 to 21 hours depending on the freezer temperature, so in practice a rack gives one cycle a day.
A domestic chest freezer may not hold its target under a full load and frequent door openings, so the plate freezer is kept separate from the general-purpose one. Logging the internal temperature of the existing cabinet for a week shows where it climbs during the busy hours.
