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Cargo Cool

Keeping Cargo Cool

The global network that manages your international refrigerated cargo transport is complex. The transport process for a piece of fruit, or high value cargos such as pharmaceuticals, move from a loading warehouse in one country and arrive at an unloading warehouse in another country, while involving many different modes of transportation. When these cargos require specific maintained temperatures, many shippers and exporters utilize 40-foot-long, ocean going refrigerated containers, most commonly referred to as “reefers” or reefer containers. Systems offered by Purfresh can play a central role in the assurance that these temperature controlled cargos arrive at their final destinations in quality condition.


When a reefer container is loaded, or “stuffed” as they say, with its cargo, and departs its origin warehouse, there is a long road ahead with many transport mode changes before it arrives at its final destination. One of the critical functions necessary to keep the cargo inside the reefer cool, or at protocol temperature, is the supply of power or electricity to the reefer container. Without supplying power to the reefer, the cargo inside can become damaged or completely ruined. 


Almost all international refrigerated cargo containers require a supply of 460 volts of electricity in order to operate their cooling systems. The following is the most common chain of events that provide power to a reefer container during an international trip:

  • Diesel generators are attached to the container or truck chassis, while the container is being trucked from the origin warehouse to the nearest ocean port.
  • When the reefer arrives at the ocean port the power is disconnected from the independent diesel generator, and is reconnected to land based power supply at the port, where the container may wait several days before it is loaded onto a container ship.
  • When the reefer is loaded onto the ship, the land based power is disconnected and then power is reconnected aboard the ship - supplied by the ship’s generators. 
  • After the ship departs the origin ocean port, in many cases the reefer container will travel thousands of miles to a hub or transshipment port, where the reefer will be offloaded from one vessel and reloaded onto a different vessel.
  • While at the transshipment port, the power supply to the reefer must be disconnected and reconnected two more times, as it is normal for the container to wait at the transshipment port for a few days before it is loaded onto the connecting ship.


Then after a few thousand miles more, when the connection ship arrives at the cargo’s destination port, the reefer container will again have to disconnect and reconnect power several more times as it moves from the ship to the port, and then finally back onto a truck for delivery to a warehouse.


During all of these disconnections and reconnections to its power supply, the reefer container still needs to maintain internal cargo protocol temperature during their 15 to 50 day trip. That is why all reefer container walls are constructed with several inches of insulation material to help keep the cargo cool or at temperature. It is expected that the insulation system of the reefer container is able to maintain internal cargo area temperatures within 1-2 degrees Celsius of the cargo protocol temperature, even with average power disconnection time periods of 1 to 6 hours during its trip.

Global reefer monitoring systems such as Purfresh can remotely identify and communicate alert information when the power supply to the reefer container has been disconnected or shut off for too long. Corrective action can then be taken before the lack of power causes damage to the cargo inside the reefer, in many cases with values of $50,000 to $500,000 USD. Many shippers, exporters, logistics companies, and importers use Purfresh systems to help protect their cargo with either real-time temperature monitoring and/or controlled atmosphere management. Purfresh products reduce the risk of cargo loss, and help to ensure quality arrivals for fresh fruit and other high value cargo, transported internationally by refrigerated containers. 



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