Good Loading Practices Carrier Transicold and PLM Trailer Leasing.
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Transcript of Good Loading Practices Carrier Transicold and PLM Trailer Leasing.
Good Loading Practices
Carrier Transicold and PLM Trailer Leasing
Transport Refrigeration what is its purpose
To maintain the Temperature of the Product
It is not designed to reduce or increase the temperature of the product
Summary of good practices
A well maintained working unit Reefer and Trailer
A Pre-Cooled box
Good loading conditions and practice
Consequences Chilled pork Optimum 29 Degrees F Rule of thumb : 2 Degree Increase =
10% decrease in shelf life
29F - 100% Life Attainable 32F - 70% 34 F-60% 36 F - 50% 41 F - 30%
Heat Sources
1. Through the body2. Through the rear door3. Warm Products4. Door Seal
Modern Longitudinal Divide
KemliteSmall door opening to retain cold
Flat floor
“E” Track
Three years old ?
Three years old ?
Bulkheads
Bulkheads
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
Side Doors
Side doors should be kept as small as possible
Curtains and door seals should be well maintained
Flat Floor and “T “ Floor
Unless palletized multi temp
“T” Floor is recommended
Flat Duct Board
Inspect Equipment - Debris
Swing Doors V Roll up Door
Roll up is 25% less efficient Swing doors
can open oneside and retainthe cool
Curtains
Curtains are recommended for both rear and side doors
These should overlap by 2”
Rear Door Side Door
Types of Bulkheads
Mattress type bulkhead
Rigid type bulkhead with door
Air ChutesRecommended by Refrigerated Transportation Foundation
Proper InstallationRequired
Unit Positioning
Unit should not bepositioned any lower than normal
Air will hit the top of the load and short cycle
Summary of good practices
A well maintained working unit Reefer and Trailer
A Pre-Cooled box
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
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
Summary of good practices
A well maintained working unit Reefer and Trailer
A Pre-Cooled box
Good loading conditions and practice
Loading PracticesAirflow - Return
Air Flow down the side of the load
Minimum 1”airflow around the sides of load preferably 2”
Properly loaded pallet giving good airflow
Minimum 4” from the rear door
Short Cycling
Loading to the ceiling will cause short cycling
Loading Procedure
Poor air distribution is one of the primary causes of product deterioration even when unit capacity is more than adequate
Obstruction anywhere around the load can result in hot spots
Product should be loaded at correct temperature
Product should alwaysbe loaded at the correct temperature transport refrigeration is designed to maintain temperature only
Product should be loaded from a refrigerated loading bay
Different Containers
Do not use plastic wrap on fresh produce as it prevents air circulation reaching the load
Fresh FrozenProducts Products
Correct Pallets should be used
Pallets should allow airflow through and under the load
Orientation should allow airflow to the rear of the body
Load Properly
Do not mix refrigerated and dry goods in the same compartment
Separate items
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
Typical heat gain (Btu/hr) from 15 min door openings in a 10 hour period
Trailer setpoint Average number of door openings per day
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
Loading Procedure
Pre-cool the box preferably until setpoint Initiate Manual Defrost during pre-cool Switch off the unit Load product at the correct temperature and in the
correct mannerClose doors Start up unitCheck thermostat settings
Do not load the product in front of the evaporator air outlet as this will block the airflow
Blockage above the load will result in short cycling
Leave a minimum of 9” between the top of the load and the ceiling
Inside of the truck should be clean and the floor free of shrink wrap and debris
Loading Procedure
Good Loading Procedure
Do not block the evaporator inlets (return air ) Make sure that the return air bulkhead is in a
good condition Keep the trailer door seals in good conditionUse air curtains wherever possible Keep door openings to a minimum Turn off unit while doors are open