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Published byAbraham Herndon Modified over 10 years ago
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Good Loading Practices Carrier Transicold and PLM Trailer Leasing
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Transport Refrigeration what is its purpose ê To maintain the Temperature of the Product êIt is not designed to reduce or increase the temperature of the product
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Summary of good practices ê A well maintained working unit Reefer and Trailer êA Pre-Cooled box êGood loading conditions and practice
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Consequences è Chilled pork Optimum 29 Degrees F è Rule of thumb : 2 Degree Increase = 10% decrease in shelf life è 29F - 100% Life Attainable è 32F - 70% è 34 F-60% è 36 F - 50% è 41 F - 30%
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Heat Sources 1. Through the body 2. Through the rear door 3. Warm Products 4. Door Seal
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Modern Longitudinal Divide Kemlite Small door opening to retain cold Flat floor E Track
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Three years old ?
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Bulkheads
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Pallet stop to protect bottom of bulkhead Bulkheads should be sealed around the sides to make sure the air does not short cycle Minimum 4 from the front of the trailer to allow adequate air return
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Side Doors Side doors should be kept as small as possible Curtains and door seals should be well maintained
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Flat Floor and T Floor Unless palletized multi temp T Floor is recommended Flat Duct Board
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Inspect Equipment - Debris
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Swing Doors V Roll up Door Roll up is 25% less efficient Swing doors can open one side and retain the cool
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Curtains Curtains are recommended for both rear and side doors These should overlap by 2 Rear DoorSide Door
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Types of Bulkheads Mattress type bulkhead Rigid type bulkhead with door
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Air Chutes Recommended by Refrigerated Transportation Foundation Proper Installation Required
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Unit Positioning Unit should not be positioned any lower than normal Air will hit the top of the load and short cycle
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Summary of good practices êA well maintained working unit Reefer and Trailer êA Pre-Cooled box
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Pre Cool the body Removes the heat that has entered the body from the sun When not in use try to park in the shade
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Typical Heat Gain from Infiltration through the body UA Factor -20F 0F 35F 110 UA 13,200 11,000 7,150 120 UA 14,400 12,200 7,800 130 UA 15,600 13,000 8,450 140 UA 16,800 14,000 9,100
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Summary of good practices êA well maintained working unit Reefer and Trailer êA Pre-Cooled box êGood loading conditions and practice
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Loading Practices Airflow - Return
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Air Flow down the side of the load Minimum 1airflow around the sides of load preferably 2
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Properly loaded pallet giving good airflow Minimum 4 from the rear door
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Short Cycling Loading to the ceiling will cause short cycling
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Loading Procedure è Poor air distribution is one of the primary causes of product deterioration even when unit capacity is more than adequate è Obstruction anywhere around the load can result in hot spots
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Product should be loaded at correct temperature Product should always be loaded at the correct temperature transport refrigeration is designed to maintain temperature only Product should be loaded from a refrigerated loading bay
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Different Containers Do not use plastic wrap on fresh produce as it prevents air circulation reaching the load Fresh Frozen Products
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Correct Pallets should be used Pallets should allow airflow through and under the load Orientation should allow airflow to the rear of the body
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Load Properly Do not mix refrigerated and dry goods in the same compartment Separate items
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Cold air is heavier than hot air Opening doors with no curtains loses all the cold Something has to replace the heavier air and the warm ambient does this instantly Door switch is recommended
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Typical heat gain (Btu/hr) from 15 min door openings in a 10 hour period Trailer setpoint Average number of door openings perday 2 4 8 12 35f Btu / hr 560 1,125 2,250 3,375 0f Btu / hr 750 1,500 3,000 4,500 -20f Btu / hr 935 1,875 3,750 5,625
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Loading Procedure ê Pre-cool the box preferably until setpoint ê Initiate Manual Defrost during pre-cool ê Switch off the unit ê Load product at the correct temperature and in the correct manner êClose doors ê Start up unit êCheck thermostat settings
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è Do not load the product in front of the evaporator air outlet as this will block the airflow èBlockage above the load will result in short cycling èLeave a minimum of 9 between the top of the load and the ceiling èInside of the truck should be clean and the floor free of shrink wrap and debris Loading Procedure
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Good Loading Procedure èDo not block the evaporator inlets (return air ) è Make sure that the return air bulkhead is in a good condition è Keep the trailer door seals in good condition èUse air curtains wherever possible è Keep door openings to a minimum è Turn off unit while doors are open
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