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 body
2. Through the rear door
3. Warm Products
4. Door Seal
Modern Longitudinal Divide
“E” Track
Kemlite
Small
door
opening to
retain cold
Flat floor
Three years old ?
Three years old ?
Bulkheads
Bulkheads
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
Pallet stop to protect bottom of bulkhead
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
Duct
Board
Flat
“T” Floor is recommended
Inspect Equipment - Debris
Swing Doors V Roll up Door
Roll up is 25%
less efficient
Swing doors
can open one
side and retain
the cool
Curtains
Curtains are
recommended
for both rear and
side doors
Rear Door
These should overlap by 2”
Side Door
Types of Bulkheads
Mattress
type
bulkhead
Rigid type bulkhead with door
Air Chutes
Recommended by
Refrigerated
Transportation
Foundation
Proper Installation
Required
Unit Positioning
Unit should not be
positioned 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
110 UA
120 UA
130 UA
140 UA
-20F
13,200
14,400
15,600
16,800
0F
11,000
12,200
13,000
14,000
35F
7,150
7,800
8,450
9,100
Summary of good practices
A well maintained working unit Reefer and
Trailer
A Pre-Cooled box
Good loading conditions and practice
Loading Practices
Airflow - 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
always
be 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
Products
Frozen
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 manner
Close doors
 Start up unit
Check thermostat settings
Loading Procedure
 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
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 condition
Use air curtains wherever possible
 Keep door openings to a minimum
 Turn off unit while doors are open