Reefer containers power requirement, venting heat & recording of information
Fig:Container ship at anchor
Each reefer container is estimated
to consume power of 5 KW and the
ship's main power supply should be
designed to cope with the extra load
of running its maximum capacity
of reefer containers, although if
necessary an additional generator can
be installed onboard the ship.
Power shutdowns should be kept to
a minimum. All power shutdowns
and breakdowns should be diligently
logged in order to correspond
with the records of the electronic
datacorder. It is important that
the chilled cargo containers are
reconnected as soon as possible after
any power loss.
If cargo damage is suspected, inform
the company and attempt to salvage
the maximum amount of cargo
possible by transferring it into an
empty but functioning reefer.
At the end of the voyage, disconnect
the power from the loaded reefers
just before their discharge from the
ship. Keep the power supply on as
long as practicable. Keep copies
of the Partlow charts if they were
changed during the voyage. Ensure
that documentation is properly
Reefer containers inside the cargo
hold expel heat from the air cooled
condensers when they are running.
This hot air must be vented outside
the hold or it will accumulate and the
refrigeration machinery will not work
efficiently. The blower capacity should
provide sufficient air exchange to
remove the heat extracted.
If water cooled condensers are used
there is a water circulation system
of pipes installed in the cargo hold
that can be connected to individual
reefer containers. These containers
are often marked `In Hatch Stowage
Allowed'. To determine whether a
particular reefer container is suitable
for stowage inside the cargo hatch,
simply check the water cooled
condenser inlet and outlet water pipe
1. Monitor personal safety when
- On high tier reefers
- during rough weather and
- with controlled atmosphere
2. While operating valves on
refrigerated machinery (or any
pressurised machinery) it is
important not work directly in
front of certain parts and to be
aware that the valve spindle or
other parts can fly off at high
speed. Many serious accidents
have been reported from the
valve spindle accidentally flying
off from the valve housing.
3. Refrigerants may cause frostbite
and asphyxiation. It is important
to keep away from any leaks.
Refrigerants at high temperature
can release phosgene which is a
highly noxious gas. When they
come into contact with moisture
they can also form hydrofluoric
acid, which is highly toxic,
corrosive and attacks metals.
Death can result from exposure
to hydrofluoric acid rather than
just damage to skin and eyes.
If there are any differences between
the container settings received and
the bill of lading instructions, these
should be reported immediately.
Reefer units should be inspected
at intervals not exceeding six
hours when at sea. The times of
the inspections and details of any
problems should be recorded in an
There are many situations where the
temperature tracking pattern may
be misleading and not be a precise
representation of the temperature or
condition of the cargo. Conclusions
should not automatically be made
from this temperature information
alone. For example:
1. Cargo should be loaded at
the carriage temperature
stipulated by the shippers.
However, if a container is
loaded with a cargo where the
pulp temperature exceeds this
temperature, the (warm) cargo
will cause the temperature of
the delivery air to rise rapidly
when passing around the cargo.
Eventually, the return air may
reach a temperature where the
refrigeration machinery cannot
cool it down sufficiently prior
to re-circulating it as delivery
air. The tracking pattern on
the chart or logger will show a
temperature higher than the
In most cases the difference
in temperature between the
delivery and return air will
narrow as the continuous
circulation of air cooler than
the cargo brings the cargo
temperature down towards the
2. If a refrigeration unit ceases
to operate, the chart or logger
will register a gradual but
steady rise in temperature to
the point where the ambient
temperature is recorded.
The sensor will record the air
temperature and the record
will not then accurately reflect
the true position regarding the
cargo itself. The cargo will be
reasonably well protected from
the influences of the external air
temperature by the surrounding
3. The return air temperature
sensor is positioned close to
to the refrigeration machinery
and the temperature record will
register some increase during
defrosting. These increases,
which are noticeable on paper
chart recorders, do not have
an immediate effect on the
actual temperature of the
cargo and do not indicate an
unstable refrigeration unit.
Electronic loggers usually
indicate the timing and lengths
of defrost periods in addition to
If erratically functioning reefer
machinery cannot be fixed during
the sea transit, the vessel should
advise its owners and agents at the
next port prior to their arrival so
that arrangements can be made to
correct the problem ashore. In these
circumstances a Surveyor should be
appointed to attend the vessel on
arrival in order to inspect and report
on the condition of the cargo and
If a container sustains any physical
damage the agent and/or the
surveyor must ensure that action
is taken to rectify the problem as
quickly as possible so as to minimise
potential cargo loss.
Where there is a discrepancy in the
temperature on the reefer and in the
manifest, the matter must be referred
to the company for clarification. Do
not make assumptions as either could
Confusion between the temperature
units of degrees Celsius or Fahrenheit
has lead to much cargo damage.
Do not make assumptions, obtain
Most units have a critical alarm
signal (LED) which when lit,
needs immediate attention and
- The `in range' light on the display
panel should be illuminated.
This shows that the air
temperature at the controlling
probe (irrespective of whether it
is chilled cargo or frozen cargo)
is satisfactory and within limits.
In certain circumstances such
as defrosting, this `in range' light
may not be lit continuously.
However, when the unit returns
to its normal cooling mode of
operation, and settles down to
a stable operation, the `in range'
light should be illuminated
- if the red light indicating a
critical alarm is lit, it requires
immediate investigation and the
necessary corrective action
- earlier models used LED
temperature displays that
could be seen from a distance.
Unfortunately, most units now
have LCD displays that are
difficult to read from a distance.
If damage or a loss of quality in the
cargo is detected at the end of a
trip, the record of the temperature
maintained inside the container
and the performance record of the
reefer machinery will be examined
to establish the cause and the extent
of the damage and to identify the
responsible party. The record of
temperature maintenance is called for
by the courts in order to determine
the integrity of a cargo damage claim.
Our detail pages contain many topics related with refrigeration process of various commodities and prepare for shipment , maintaining temperature in reefer containers ,troubleshooting etc.
- Precautions when working in refrigerated spaces
- How to change-over of refrigerants of a reefer container ?
- How to maintain compressor oil level of a reefer container ?
- Function of refrigerant receiver & where it is located?
- Maintenance requirement of condenser of a reefer container
- Reson of compressor failure and troubleshooting
- Maintenance of evaporator coil - how to replace the evaporator fan ?
- Maintenance of expansion valve
- Inspection of reefer components
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All information contained in this website is for preliminary
information only and is not legally binding. The publisher of this website cannot take responsibility for any damage to your reefer cargo due inadequate data or errors. For any remarks please
We choose to refrigerate commodities such as fruits and vegetables because we want to prolong their “practical shelf life” – the time from harvest until the product loses its commercial value.
- How refrigeration process works in a reefer container ?
- Chilled and frozen refrigerated cargo - stuffing requirements
- Integrated reefer containers transporting commodities at trans-ocean services
- Maintenance requirement for integrated reefer containers