FEATURE
INCORPORATING COLD CHAIN
Pros and cons of pallet conveyors
By James Cunningham of Barpro Storage
allet conveyors, which move
pallets of frozen product into and
out of freezer stores, have had a
chequered history in South Africa. They
were popular over 20 years ago, with
extensive systems being installed in several
cold stores. Thereafter, they became
unpopular but now there is a marked
resurgence of interest.
ADVANTAGES
While some recent enquiries may be
due to increasing energy costs, there
are several other reasons why conveyors
should be considered in both cold and
freezer stores.
1.Overcoming floor height differences
Older freezer stores were built on
ground level rather than at 1.5m, to
allow for direct fork truck access. When
raised loading areas were added to
improve loading efficiencies, conveyors
working in conjunction with reach or
counterbalanced trucks, were and still
are a useful way to bridge such height
differences that can be so problematic for
forklift and reach trucks.
2.Freezer room energy control
Solid ‘night’ doors, often 2.4m wide by
up to 5m high, are not a good way to
conserve energy. Often left open, they
allow, even with strip curtains, for large
volumes of expensive cold air to escape
as well as for large volumes of moist warm
air to enter the freezer chamber. Doorways
being the most energy expensive part of
a cold room, several alternatives to night
doors have been developed, most of
which have received attention in previous
issues of this publication.
For energy saving, conveyors are
attractive as hatches only need to be
slightly bigger than the loaded pallet.
However, the hatch arrangement needs to
be designed so that there isn’t a snow/ice
build-up around the conveyor inside the
store. Reach trucks and forklifts enter the
freezer via a larger door that then remains
closed. Where a normal freezer store
entrance can be 13m 2 , a conveyor hatch
can be as little as 2.5m 2 . Even if there are
two hatches, one each for the in and out
feed conveyors, the combined opening
area is still reduced by around 60%.
Storage
P
We explore the advantages and disadvantages of pallet conveyors in cold and freezer stores
to see when they are a good option (and when not).
While there are few South African stores with pallet conveyors designed for
dual cycling, dual cycling can significantly increase productivity.
3. Maintenance of product temperatures
Conveyors are a great way to
keep frozen product at operating
temperatures before dispatch or before
being put away in the racking system.
The pallets sit on the conveyor inside the
store with only one pallet on the outside.
Truckloads of pallets may be left on the
‘warmer’ loading dock for up to an hour
before they are put away in the freezer
or loaded for that matter.
Airlock over pallet conveyor inside freezer to stop the inflow of moisture.
Conveyors can be designed to operate
bidirectionally to cope with large
movements of product either in or out of
the freezer, where both conveyors are
temporarily switched to run in the same
direction. This feature does add to the
cost, however.
After fading in popularity in cold stores, it seems that pallet conveyor systems
are picking up again.
4. Equalising work rates inside the freezer
and on the loading dock
As the pallet numbers moving into and
out of cold stores continue increasing,
counterbalances or man on movers
COLD LINK AFRICA • May 2019
on the loading dock will move pallets
at a different rate to the reach trucks
working in the freezers. At times, the
work rates will be similar but at others, it
will differ significantly, resulting in either
the loading dock or freezer forklifts/
reach truck work rates constantly
changing. Frequently, one set of
machines will stand idle until the other
has caught up.
Continued on page 47
www.coldlinkafrica.co.za
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