Pre-cooling of Container

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Pre-cooling of Container

  • It is important to note that containers are not designed to pre-cool products. Pre-cooling is a separate operation performed prior to storage or transportation that requires special equipment or cooling facilities. Refrigerated containers will maintain cargo temperatures at the PRODUCT pre-cooled level OR PRE SET TEMPERATURE LEVEL.
  • Pre-cooling of the reefer container itself should not take place unless temperatures in the cold store and in the container are identical and a "Cold Tunnel" is used.
  • A Cold Tunnel is a tight duct between the cold store and the container, which prevents ambient air from entering. If the container is pre-cooled in an open environment, ambient hot air will meet internal cold air once the doors are opened resulting in condensation on the interior surfaces. Condensed water can drip from the roof of the container and cause stains and frost on the boxes.
  • If loading in a Cold Tunnel concept, the machinery may operate during loading.
  • Do not operate reefer machinery when container doors are open.
    • Hot ambient air will rapidly move into the container and heat up the cargo instead.
    • When humid air enters the reefer, moisture condenses on interior surfaces and product which may cause quality of outturn at destination.

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  • If inland transit time is greater than 2 hours for chilled cargo and 8 hours for chilled cargo, it is recommended to use the generator set to supply power to container during inland tracking (8 hours for frozen cargo). IF A GENERATOR IS NOT AVAILABLE, THEN IT SUGGESTED THAT THE CONTAINER IS PLACED ON POWER FOR AT LEAST 6 HOURS PRIOR TO THE TRANSPORT . THIS WILL ALLOW THE MACHINERY TO EXPELL THE AMBIENT AIR THAT HAS ACCUMULATED INSIDE THE CONTAINER DURING LOADING. THUS THE PRODUCT TEMPERATURE IS STABILISED BEFORE TRANSPORT. FOR A 40? REEFER IT IS ESTIMATED THAT APPROXIMATELY 10 TO 13M3 OF AMBIENT AIR IS ACCUMULATED INSIDE THE CONTAINER.
  • Laden heat from external ambient may cause raise in carriage temperature if the reefer unit is left off power for too long.
  • Hence it is always recommended to truck reefer cargo during cooler climate (at night) or with clip on generator set to ensure continue power supply during land transportation.