Reefer container (refrigerated container) is a refrigerated box used for transporting
temperature sensitive and perishable cargoes. It has an integral refrigeration unit
that required external electrical power to run the system and some are equipped with
cooling water system capable to be loaded in the ship’s cargo hold. There are 20
footer (standard) and 40 footer units that are being used and transported by the
ships.
Reefer containers are used for goods which need to be transported at a constant
temperature above or below freezing point. These goods are divided into chilled
goods and frozen goods, depending on the specified transport temperature. They
principally include fruit, vegetables, meat and dairy products, such as butter and
cheese.
7.9.1 Reefer Containers Components
The refrigeration unit provides; dehumidification process for ensuring optimum
humidity inside the container, controlled atmosphere providing optimum conditions
for the cargoes or products loaded that improved quality and shelf life and capable of
maintaining low temperatures as low as -60oC for special reefers.
a. Compressor Unit
Different types of compressors are installed and mostly are maintenance free
type. They are the hermetic, semi-hermetic, scroll type compressors, etc. The
compressor is used in the refrigerating unit to circulate, evacuate and
compressed the refrigerant into a higher pressure from the evaporator (low
pressure) and discharge to the condenser.
b. Condensing Unit
The condenser either air cooled or water cooled or sometimes dual cooling unit
are installed just above the compressor. The condensing unit provides heat
exchange from gas refrigerant to liquid refrigerant. When the fan is used, it is
automatically controlled by the controller in the main control unit and can
start/stop automatically depending on the temperature setting.
c. Evaporating and Control Unit
The evaporator, fans and expansion valve (thermostatic, electronic, etc.) are
installed on the upper part of the reefer container with various sensor attached
(supply air temperature, return air temperature, etc.) to maintain the cooling
requirements of the unit.
d. Temperature Indicator and Recorder
Temperature indicators and recorders can be of digital unit or mechanical unit. In
reefers using mechanical unit indicator and recorder, the temperatures are written
in partflow chart by a stylus pencil attach through the unit. The chart is capable to
record up to 30 days in either the supply or the return air temperature monitored
inside the reefer container.
Digital temperature indicators and recorders can display the actual temperature
inside the reefer unit and records it in the read only memory in the main control
unit. The temperatures recorded can be read through a digital display and
permanently installed in the memory chips for further retrieval.
Modern reefer units can be both provided with the mechanical and digital
indicator and recorder or digital unit alone.
7.9.2 Handling Procedures
a. At the Loading Stage
i. Reefer List
The Reefer List will be handed to the ship’s Chief Officer from the Terminal Operator
or the Agent. All reefers to be loaded at the terminal are registered on the list and the
container number, stowage, temperature and ventilator settings are to be confirmed.
Estimated time of loading for each container and whether re-handling of loaded
containers are necessary should be confirmed with the terminal operator.
ii. Loading containers
After the containers have been loaded to the ship, the below mentioned duties will be
completed by Stevedores or ship crewmembers. Even if the Stevedores completed
these duties, confirmation by the ship's crew is essential.
Generally speaking, connecting the power plugs and the water hoses should be
done by crew hands.
a. Connecting the Power Plugs
Caution: For dry cargo that are stuffed into a reefer container which does not require
temperature control, some booking lines thus declare the container as “NON
WORKING” or “as dry” on the Reefer List. “NEVER PLUG IN THE CONTAINER” and
confirmed beforehand that it is not plugged in.
In one case on a consortium vessel; reefer container has been loaded onboard
in which wines were stuffed as dry was mistakenly plugged in by a Stevedore and
nobody on the vessel noticed the error, all the wine froze and the bottles were
broken. Generally, such containers do not require a power supply, but this should be
confirmed with the Terminal Operator.
b. Connecting the Monitoring Cable
Note: Connection of the 4-pin monitoring cable is not usually required. However,
it should be utilized if a reefer needs to be monitored.
c. Reefer Container Loaded into the Cargo Hold
When the cooling water hoses are needed due to variation of weather or
circumstances where ambient temperature in the hold is especially forecasted to
rise, all reefers equipped with a water-cooled condenser should be connected to
the cooling water hose.
In addition, in which case where a reefer is not equipped with a water-cooled
condenser, loaded into the cargo hold and does not maintain the setting
temperature due to high ambient temperature, connecting of the cooling water
hose of other reefers which are equipped with a dual condenser (air-cooled/
water-cooled) is effective. It can then control the heat from the unit and avoid
increasing the ambient temperature in the cargo hold.
d. Starting of Unit
When the reefer containers are been loaded onboard and as much as possible
before starting the unit, the ship’s crew must check and ascertain the following
condition:
i. External condition
Any questionable damage on the reefer unit should be examined. Serious
damage should be reported to the Terminal Operator immediately. If any damage
occurs during cargo work, a Stevedore Damage Report should be issued and
signed by the Terminal Operator.
ii. Ventilator
In the case where the Reefer List has already been received, it should be
confirmed if the actual ventilator setting is in accordance with the ventilator
setting declared on the list.
If the Reefer List has not been received, it should be confirmed that the ventilator
for frozen cargo is closed, not open. Also, confirm that the actual ventilator setting
is in accordance with the ventilator setting indicated on the list, and enter the
ventilator setting on the Monitoring Sheet for Refrigerating Containers (Monitoring
Log) for evidence of onboard confirmation.
In addition, locking of the ventilator should be confirmed.
iii. Running condition
After starting the unit, the following items should be monitored:
a. Check any abnormal positions in the switches and warning lights.
b. Check any abnormal noises and vibration.
c. Record the actual setting temperature. If the Reefer List has already been
received, confirm that the actual setting temperature is in accord with the setting
temperature declared on the list.
d. Record the chart temperature. Confirm that the indicated temperature on the
chart recorder (chart temperature) is in accord with the digital temperature on the
indicator (digital temperature). If needed, carry out calibration of the chart
recorder.
e. Check for any lubricating oil stains around the compressor and piping and
determine if there is any refrigerant leakage.
f. The Moisture Indicator should be bright green.
g. Check for any unusual frosting on the piping and the compressor. As for the
carrier’s unit and Daikin’s unit in chill mode operation, it will be found that the
compressor frosts more than other maker’s compressors. Check using the
illustration on the unit.
h. Check the drain hose and piping if they clog.
