The majority of refrigerated containers are integral units either 20ft or 40ft long. To activate the built in refrigeration plant they need to be connected to an electricity supply. This would be the ships system whilst at sea, the ports system whilst on quay and, if required, to a portable power source called a genset during inland transportaion. Port Hole or Con Air reefer (sometimes called Fruit boxes) are insulated containers without any built in machinery and require connection to a refrigeration plant during transit. They are used mainly for port to port shipment on traditional reefer trade lanes. Rare nowadays are self sustaining units which have both refrigeration plant and electricity generator built in. These just need fuel to work.

Reefers have become more sophisticated over the years, with the advent of super units capable of maintaining extremely cold temperatures and Controlled Atmosphere containers specifically designed for the carriage of live produce such as fresh fruit or vegetables. Most 20ft containers are 8ft 6" high and 40fts either 8ft 6" or 9ft 6" high. See Container Specifications

Reefer containers are designed to maintain a temperature throughout the transport and the temperature of the cargo upon loading therefore should always mirror the required carrying temperature. Typical carriage temperatures

Most refrigerated containers are bottom air fed, that is the cold (or warm) air is fed under the floor of the container. It is important therefore that the floor area is covered to ensure even distribution of the air being fed into the container. For Frozen cargo it is usually best to block stow, wall to wall so that the cargo remains enveloped by the cold air. For chilled or live cargo it is usually desirable for air to circulate through the product.

Refrigerated Containers will have a load line usually about 6 inches from the ceiling and cargo should not be loaded above this point.

After loading and without connection to power a reefer’s insulation under normal conditions will maintain a cargos loaded temperature for 24 hours so most inland haulage is effected with the container “non operating”. There are of course exceptions to this general rule and for particularly sensitive cargo or overland journeys we would recommend active refrigeration throughout.

FACTORS TO BEAR IN MIND WHEN LOADING YOUR CARGO INCLUDE:

• Optimum carriage temperature (which should generally be the same as the storage temperature).
• That the floor of the container should be covered and the load spread evenly.
• Whether to load loose or on pallets.
• Type of packaging that best suits your cargo - should you use pallets ?
• Whether the cartons are capable of supporting the required stacking height.
• Whether any form of ventilation is required. (Generally frozen goods require no ventilation but live cargo may require ventilation and humidity control and possibly an induced controlled atmosphere).

Controlled Atmosphere Containers ...................................

More recent developments have introduced the controlled atmosphere range of containers. These containers have computerised climate control systems which can change the amount of oxygen, carbon dioxide and nitrogen present in the container thus slowing the ripening process and prolonging the shelf life of transported product. The introduction of these controlled atmosphere containers allows a greater range of commodities (perhaps otherwise requiring expensive air freight shipment) to be transported by sea. Many products currently shipped without controlled atmosphere may benefit from a switch to this method of transportation as it may well result in an extension to the products shelf life and a reduction to product loss caused by deterioration. We would be pleased to receive any enquiries from customers curious to see if the use of controlled atmosphere containers would benefit them.