The correct name for a reefer is temperature-controlled container. The GDV Container Handbook uses exactly that term: the unit does not chill the cargo, it holds the temperature set at loading for the whole carriage. According to ISO 1496-2, the internal width of a temperature-controlled container must be 2200 mm; the floor is a T-shaped aluminium grating that a forklift can drive onto.
What the ATP class promises
The UN ATP Agreement sorts refrigerated equipment into classes. Each class defines how far the inside of the box can be pulled down and held with the outside air at +30 °C. ATP covers land transport; for a reefer at sea the class matters on the road legs to and from the port and when comparing equipment. Türkiye joined the agreement in 2012, and TSE has been issuing Turkish ATP certificates since 15 May 2017.
| ATP class | Setting for mechanical equipment | Outside test temperature |
|---|---|---|
| A | any value between +12 °C and 0 °C | +30 °C |
| B | any value between +12 °C and -10 °C | +30 °C |
| C | any value between +12 °C and -20 °C | +30 °C |
| D | fixed, +2 °C or lower | +30 °C |
| E | fixed, -10 °C or lower | +30 °C |
| F | fixed, -20 °C or lower | +30 °C |
The class is clear on paper, but the real question shows up in the record. The contract should state the target temperature and the equipment class together. A class D unit holds at most +2 °C, a class F unit goes down to -20 °C; for frozen cargo the two are not the same machine.
Hours without power. ATP asks passive equipment, which relies on ice, eutectic plates or dry ice, to hold the carriage temperature for at least 12 hours without renewing the cold source. A reefer has no equivalent official period, so 12 hours serves here as a yardstick. Example assumption: 9 hours in port, 4 hours on board, 7 hours at the transhipment port, 20 hours unplugged in total. Calculation: 20 - 12 = 8 hours beyond the yardstick. Who carries those eight hours, and whether power returns on time, has to be written into the contract.
Airflow follows the stacking pattern. A reefer blows cold air forward through the T-grating floor and draws it back over the top of the load. Packing pallets tight to the doors, laying cardboard on the floor or stacking to the ceiling breaks that loop. Where it breaks, the goods warm up, and it stays invisible in the record: the return-air probe still reads correctly.
Three checks and a record
Before loading three things are checked: the box is pre-cooled, the air channels are clear, the door gasket is intact. Most lines pre-cool the container but not the cargo: the core temperature of the goods has to be on target at the moment of loading. The independent logger's serial number, position and file owner go into the shipping record.
Write the delay scenario in advance: who plugs the box in if the vessel is missed or customs holds it, who pays, and how long the goods can wait at what temperature. Ask the carrier for the route, planned transfers and delay alerts in writing.
Between seller and buyer, risk and cost are set by the Incoterms 2020 rule; between shipper and carrier, liability is set by the transport contract.
