Refrigerated cargo

Air always takes the path of least resistance. If air gaps or chimneys are left in a stow, they provide an easier route for airflow than that through the cargo. Air that does not go through the cargo cannot remove respiratory heat, and air moving through chimneys near the air distribution area cannot reach further parts of the cargo. Gaps and chimneys therefore reduce the capability to maintain temperature; ergo, the cargo must cover the entire T-floor to ensure proper distribution of temperature-controlled air.

When the cargo does not cover the entire T-floor, some type of filler material (heavy cardboard, dunnage, etc.) must be placed wherever there is no cargo. This prevents a short-circuiting of the circulating air, and forces air up and through the cargo to ensure proper air distribution in reefer containers with bottom air supply. Improper stuffing, and consequently the bypassing of circulating air, initiates a larger spread of temperatures within the cargo and can lead to severe cargo damage. It is important to ensure that air can circulate under, over and to each side and end of the stow and, in the case of respiring cargo, throughout the load.

As air provides an additional insulation against the ambience, the load should not be squeezed into the container – a space of a few millimeters to the side walls of the container should be left in order to allow air circulation between the cargo and the inner surface of the container.

Please note: In a reefer container, both the cargo and any filler material must be blocked and braced to stop the load from shifting. This graphs are general schematic illustrations depicting air circulation in reefers only and do not show any required cargo-securing material.

This graph shows an alternative stuffing method that is often used for fresh bananas to ensure proper distribution of temperature-controlled air. Instead of covering the T-floor and pallet face at the door end (bottom blocking), a sponge foam block or cardboard is placed on top of the last pallets, between the last carton row and the container ceiling.

Please note: In a reefer container, both the cargo and any filler material must be blocked and braced to stop the load from shifting. This graphs are general schematic illustrations depicting air circulation in reefers only and do not show any required cargo-securing material.

Chilled meat is a premium cargo that continues to ripen during shipment. In this illustration, the degree of airflow through the cargo is largely dependent upon the stuffing pattern at the doors.

Please note: In a reefer container, both the cargo and any filler material must be blocked and braced to stop the load from shifting. This graphs are general schematic illustrations depicting air circulation in reefers only and do not show any required cargo-securing material.

In the case of pre-cooled frozen goods, temperature-controlled air only has to flow around the cargo, since no heat has to be dissipated from the cargo itself. Only the heat that penetrates the insulation from outside (and the heat of the fan motors) has to be removed.

If frozen cargo is pre-cooled to the correct carrying temperature as prescribed, it is only necessary for air to circulate around the periphery of the load. A block stow, i.e., one that has no deliberate spacing between any of the packages or pallets, is all that is required to avoid air short-circuiting. It is, of course, necessary to ensure that air can circulate under, over and to each side and end of the stow.

Please note: In a reefer container, both the cargo and any filler material must be blocked and braced to stop the load from shifting. This graphs are general schematic illustrations depicting air circulation in reefers only and do not show any required cargo-securing material.