Reefer Container Selection
Refrigerated transport containers (reefers) come in standard 20-ft and 40-ft configurations. Key specifications include temperature range (-30ยฐC to +30ยฐC), air circulation (top-air or T-floor), and power supply (diesel generator set or shore power). Selection starts with the cargo: the set point the product requires, the heat the load will release during the journey, and the duration of the trip. A container matched to its load holds temperature more steadily than one that is heavily underloaded or packed to the ceiling.
Air circulation is the specification that is frequently misread. Top-air units deliver cold air along the ceiling and return it through the floor; T-floor units use a fluted floor to distribute air beneath the cargo. In both designs the cargo must not block the return path, or the unit cools the air above the goods instead of the goods themselves.
Temperature Monitoring
Modern reefer containers are equipped with IoT temperature sensors that provide real-time monitoring. Data loggers record temperature at intervals of 1-15 minutes, providing a complete chain of custody record. This data is critical for HACCP compliance and quality assurance.
Sensor placement matters as much as sensor accuracy. Supply-air and return-air readings describe how the equipment is performing; a probe placed in the cargo describes how the product is responding. Comparing the two is what reveals a developing problem before it becomes a claim at destination.
Loading and Handling
- Pre-cool the cargo before loading instead of asking the container to remove field heat or residual cooking heat.
- Keep carton vents aligned, and keep pallets clear of the evaporator and the return-air openings.
- Inspect door seals and look for panel or floor damage before departure.
- Record set point, actual temperatures and load condition at handover, so responsibility at each transfer point is documented.
Contingency and Records
A plan for delay, breakdown or customs hold is part of transport refrigeration: a defined response such as transferring the load, changing destination or notifying the consignee protects both the cargo and the record. Monitoring data should be downloaded per shipment and kept with the batch documents, both for traceability and for reviewing how the equipment performed on that trip.