What is Reefer Container?
A reefer container is a thermal freight container with an integral refrigeration unit that holds cargo at a set temperature, often with control of humidity and fresh-air ventilation, throughout the transport chain. ISO 1496-2 sets the specification and testing requirements for series 1 thermal containers used in international road, rail and sea transport, covering insulated, mechanically refrigerated, expendable-refrigerant, heated, and refrigerated and heated types. The standard defines a thermal container as one with insulating walls, doors, floor and roof designed to delay heat transmission between the inside and the outside. Mechanically refrigerated units draw power from the ship, from terminal reefer points, or from a generator set (genset) during road haulage. Common variants include 20-foot and 40-foot high cube reefers and units with controlled atmosphere for produce that needs a modified gas mix.
Why it matters for forwarders
The booking and shipping instructions must state the setpoint, the temperature unit (Celsius or Fahrenheit), and the ventilation and humidity settings, and an error in any of them can ruin the entire load. Reefer units are built to maintain carriage temperature, not to pull it down, so cargo should be pre-cooled before stuffing and the empty unit should pass a pre-trip inspection (PTI) before release. Terminals usually bill plug-in or monitoring charges, and the pre-carriage needs a genset and a delivery slot that keeps the container powered as continuously as possible. If the consignee raises a quality complaint, ask the carrier for the controller data download promptly, because the unit's log is the primary evidence of what temperatures the cargo saw. Equipment availability is a real constraint, so confirm empty reefer release at origin before committing to a sailing.