How to prevent reefer cargo deterioration ? Technic of Controlled Atmosphere (C.A.)
A reefer container, also identified as a refrigerated container, is an isolated container provided with a cooling unit. This unit is electrically powered and performs refrigerated transport over longer periods possible.
Reefer containers require special care after they are loaded onboard ship. These containers need to be supplied with power, monitored closely for proper function, and repaired as required in malfunctions. The article here is about procedures and guidelines on how to troubleshoot, repair & preserve the cargo, and avoid deterioration.
Controlled Atmosphere (C.A.) cargoes :
Controlled atmosphere storage or transportation provides a means of augmenting (but not replacing)
refrigeration enhances the shelf life of fresh fruits and vegetables and has been extensively
adopted for refrigerated ships.
The respiration rate of production is closely related to its rate of maturation and subsequent deterioration.
Respiration is reduced by holding at an optimum temperature as low as possible without freezing or chilling
the produce. It may be reduced further by lowering the oxygen content of the surrounding air. Atmospheres
containing below 2% oxygen are found to be most beneficial, though the exact composition of an optimum
atmosphere is species and variety dependent. The degree of the benefit obtained from C.A. varies widely
between different types of products, and it may be advantageous to use additional controls on carbon dioxide,
humidity and ethylene level for some produce.
Low oxygen and high carbon dioxide atmospheres have also been used to slow microbiological
deterioration of fresh meat, though this is more often done nowadays using vacuum packaging or similar
techniques.
It should be noted that the shelf life of produce, previously subjected to C.A. and then stored in air,
has not been fully investigated for many varieties. It should also be noted that while some produce (e.g.
apples, bananas) may be transported without C.A. and could therefore possibly be carried without major
loss in the event of C.A. failure, much subtropical produce may not survive the length of a sea voyage
without C.A.
A common means of providing C.A. in a ship's hold involves using a nitrogen generator that uses
a membrane to act rather like a sieve and effectively separates nitrogen and oxygen from the air. A nitrogen-enriched stream (about 98% nitrogen) is injected into the hold space under appropriate controls to maintain the desired atmospheric composition. For the system to be effective, good sealing and
good control are needed.
It is essential to understand that C.A. involves flooding hold spaces with an atmosphere that will not
support human life. Safety is, therefore, a paramount issue, and control of access to cargo spaces together
with warnings and alarms is essential. Specific recommendations are provided by classification societies
such as Lloyd's Register of Shipping.
Individual ship owners/operators will provide clear instructions for the procedures to be adopted when
loading, carrying, and discharging cargo under C.A. conditions to ensure that ships' staff and stevedores are
protected. Such instructions must be followed rigorously.
Similarly, shippers will provide detailed instructions for the carriage of specific cargo, and these
instructions must also be strictly followed.
Reefer repair
a) If a temperature controlled unit malfunctions while the vessel is in port, the terminal Operator and the ship Operator’s Agent shall be notified and they will, in turn, be responsible for notifying the Container Operator which is operating the unit in question.
b) While at sea, it shall be the ship’s personnel’s responsibility to make all necessary repairs possible to any malfunctioning unit to the best of their ability and contact the charterers for advice.
Integral reefer container side air delivery
c) All repairs performed by the ship shall be documented for each container. The minimum information that must be recorded on is as follows:
i. Vessel’s Name / Voyage Number
ii. Container Number
iii. Container Operator
iv. Port of Loading / Port of Discharge
v. Refrigeration Unit Manufacturer’s Name / Model
vi. Temperature Set Point
vii. Return and Supply Air Temperature before and after repair
viii. Ambient temperature
ix. Indicated Controller Alarms
x. Ventilation Opening Scale
xi. Dehumidification Setting
xii. Date of Malfunction discovery
xiii. Date of repair
xiv. Description of work performed (including temporary repairs)
xv. Description, part number and quantity of parts used
xvi. Signature
d) The "Reefer Container Trouble Report" should be sent to the charterer and the Vessel management office.
e) If the ship requires spare parts replenishment, the ship should submit the Reefer Container Trouble Report to charterer and the Vessel management office as soon as possible after the unit is repaired.
Damage and Failure Report for Refrigeration Unit
f) If a malfunctioning unit cannot be repaired onboard, and possible cargo damage is anticipated, it shall be the vessel’s responsibility to report the situation to the Container Operator as soon as possible. This report shall include the following information:
i. Vessel’s Name / Voyage Number
ii. Container Number
iii. Load Port / Discharge Port
iv. Commodity
v. Temperature Set Point (in degrees Celsius)
vi. Work performed
vii. Current return and supply air temperature (in degrees Celsius)
viii. Current return and supply air temperature (in degrees Celsius)
ix. Ambient temperature
x. Defrost interval
xi. Stowage location
xii. ETA & Location of Next Port of Call
xiii. Status of Reefer unit
1. Electric power line
2. Condition of compressor with amperage reading
3. Alarm item
4. Discharge and suction pressure
g) If, at any time, the ship needs technical assistance addressing refrigeration unit problems, enquiries should be sent to the container operator or charterer.
Caution prior reefer loading
(1) Check and monitor each reefer container as per voyage instruction, which requires
following essential check items.
Upon sailing from a loading port, make sure ;
a) if number of reefer containers loaded matches that of reefer list
b) if the temperature of all the reefer containers loaded matches reefer list temperature
c) if ventilation setting of all the reefer containers loaded is all OK
d) if power plugs of all the reefer containers are duly connected
e) if all the reefer containers are (seem to be) working normally
(2) Once any malfunction or troubles are detected, make an immediate report to the
concerned parties as per voyage instruction. If they are reefer units, also
follow instructions provided .
Reefer Container Shipment
Procedures and guidelines for stowage of reefer containers shall be adhered to. A reefer container list or manifest must accompany every reefer container proposed for shipment. Additionally read our article on:
Reefer cargo Handling In Port Reefer containers shall be plugged in and supplied with ships power as soon as practicable after loading. In case it is to be done by shore hands, ships crew shall still closely monitor the operation and confirm that all reefer containers are supplied with power earliest after loading....
Reefer cargo care at sea At sea, all reefer containers shall be monitored by checking physically at least twice daily (weather permitting). All monitored data for each reefer container on board shall be entered in a reefer monitoring log and retained for three years. Some reefer containers with special cargo (e.g., VIP cargo) come with instructions for more frequent monitoring and reporting. Such instructions shall be strictly followed.
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Commodities Shipped In Reefer Containers Some cargoes may require controlled humidity (e.g. flower bulbs). In such cases, many refrigeration units are only capable of reducing humidity within the cargo space, and the settings should be applied accordingly.
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Reefer Cargo Temperature Recording A Partlow recorder registers temperature on a pressure-sensitive circular chart over 31 day period. If the voyage transit is expected to exceed 31 days, care must be taken to ensure charts are replaced before expiry. The first chart should be placed underneath the new chart to build up a complete temperature record for the entire voyage up until arrival at the final destination.
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Reefer Cargo Maintaining Records Monitoring the digital & chart temperatures of all reefer containers at least twice a day. Daily reefer container temperature checklists should be maintained, and printouts from monitoring unit should be preserved.....
Reefer Cargo Care During Sea Transit Reefer containers usually have their own refrigeration unit, with an air or water-cooled heat exchanger. They have a data logger to record the temperature. The logger may be in the form of a Partlow chart or a digital logger. They usually contain high-value cargo, and any damage to cargo would likely result in substantial claims......
Reefer Cargo Defrosting During the operation of a refrigeration unit, a layer of ice will form on the evaporator coils depending on the temperature set, the temperature of the cargo, the amount of fresh air ventilation and the cargo humidity.
The unit periodically enters a phase where heat is produced by a series of electrical bars, allowing defrosting to occur. At such times, all fans are turned off automatically to prevent heat from entering the cargo compartment. ....
Basic check item prior stowing Reefer Cargo Stowage location of reefers must be checked against vessels reefer receptacle locations. In case reefer containers must be loaded in random locations, it must be confirmed that monitoring and repair will be possible during the voyage, and that vessel has sufficient extension cables for providing power. ....
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