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Reefer Cargo Temperature Measurement & Recording- Certification of Reefer Containers

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. They are commonly used for carrying fruit, vegetables, or other foods. The cooling machinery is, in many cases, provided with a thermometer so that the right temperature can be set and monitored; after taking into account nature of goods being carried.

In many other type, 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 under-neath the new chart in order to build up a complete temperature record for the entire voyage up until arrival at the final destination.

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These charts should always carry the following endorsements: Data logger recorders may monitor both breaths of air, and a cargo pulp temperature within a reefer unit, and the data is stored in an electronic memory.

The memory also logs PTI (Pre Trip Inspection) results, alarms, and transit details (e.g., shifting the container in port). The information is more comprehensive and accurate than indicated by a Partlow chart alone.

Temperature Measurement

It is uncommon to find mercury or alcohol glass thermometers in use today, but it is worth covering their use. When using these instruments (apart from their fragile nature as with all types of thermometers), the sensing head (in this case the bulb) must be kept in the environment where the temperature is required to be known long enough for all the liquid in the bulb to settle to that temperature and ensure the correct degree of expansion or contraction. It must also be shielded from external sources of heat or cold. With liquid cargoes, it is simple enough to immerse the bulb for a few minutes, and in the case of solids, if not too dense, it may be possible to insert the thermometer carefully.

Reefer machinery unit
Reefer machinery

Metal sheathed (spear) thermometers enable proper penetration but require a longer time to achieve the correct temperature of the commodity being measured. In other instances, it may be necessary to drill a hole (particularly in hard-frozen commodities) to ensure penetration to the heart of the article to obtain an accurate temperature. In the case of sealed packages, such penetration may destroy or reduce their value. A close approximation of the temperature can be obtained by sandwiching the thermometer between two packages and wrapping them together for a while to exclude draughts and other outside influences.

It may well be considered advisable, on receiving a cargo of sealed packages, the temperatures of which have to be ascertained, to penetrate selected samples and ensure they are conspicuously marked so that the same packages can be used for measuring the temperature if required on discharge, thus reducing the number so damaged.

A bi-metal instrument consists of two strips of dissimilar metals with different coefficients of expansion joined together at one end, such that the varying temperature causes them to expand or contract at a different rate, this variation being accurately measured as a temperature reading, and connected to a calibrated dial.

Integral refrigerated container top air delivery

More robust than glass thermometers, they are easier to read but require more time to settle and for the temperature to be measured.

Electrical resistance thermometers depend on the resistance of a wire or filament varying in ratio to its temperature. It is necessary to have a suitable instrument to measure the resistance, calibrated in degrees of temperature, but the sensing probe may be remote from the instrument. Distant reading thermometers are of particular value during the cargo's actual carriage, as the sensing probes can be distributed amongst the stow. Then the temperature read off externally during the passage. Such instruments can also be fitted with a recording chart to give a continuous record of the temperature of the cargo during passage.

Some importing countries require proof that the requisite temperatures have been maintained for the required time. This may be to ensure cold sterilisation of the commodity with regard to parasites in living cargoes or for other temperature monitoring requirements. A temperature recording chart fitted to integral refrigerated containers may serve a similar function.

Insulated reefer container
Insulated container requiring external refrigeration source.
Bottom air delivery.

Certification of reefer containers

A reefer container's ability to maintain a given temperature when using its integral refrigeration unit is tested following ISO 1496-2. It consists of two tests: one to determine the heat loss through the container's envelope and the other to ensure the refrigeration unit can operate with a specific internal load. These tests are arranged during type approval.

The amount of electrical power required to maintain a reefer container at a given temperature depends on the size of the box (TEU or FEU), the temperature of cargo needed, the shipment being carried and the external ambient air temperature. For example, 9 kW of electrical power is needed to maintain a temperature of minus 18įC in a 40-foot container carrying frozen meat. In comparison, a container carrying fruit at 2įC requires approximately 11 kW. This is because of fruit respire and produces heat during transit. Certain cargoes, for example, bananas, may require even more power because of the more significant heat produced as they ripen. There is a high electrical load on the ship's generators when reefer containers are carried.

Instructions For Temperature Controlled Containers (Reefer Containers)

These general guidelines shall be used unless overruled by client / charterer or container operator procedures.

Electrical Power And Plug Requirements
  1. All refrigeration machinery must operate from a 380/440 volt, 50/60-cycle electrical power supply.
  2. The main power plugs shall be 380/440 volt, 32 amp type complying with ISO1496-2: 1988E and CEE-17, 3h IEC309-2 standards.
  3. It is the container operator's responsibility to ensure that the temperature-controlled units they use are designed to meet the standard ISO 1496-2.
  4. When necessary, the container operator shall supply the adapters or pigtails required when the unit's plugs are not compatible with the ship's power outlets. These can be kept on board and managed with the spare parts pool.
  5. When necessary, the container operator shall supply the step-up or step-down transformers required when their container's power requirement is not compatible with the vessel's power supply. These transformers can be kept on board and managed with the spare parts pool. All costs associated with the loading, discharging, and shifting of the transformers shall be for the booking Line's account and arrangement.

Maintenance / Operator And Parts Manual Library

a) It shall be the vesselís responsibility to ensure that all necessary tools are on board and available to perform emergency repairs to the refrigeration units. These tools shall be agreed with the management office and may typically include:-
b) All vessels shall carry a library of manuals supplied with the spare parts kits if provided by charterers.

c) If a container operator wants to ship a new or different model of refrigeration unit, he is responsible for providing one (1) set of manuals to the vessel to update the vesselís library.

d) Whenever any of the container operator phases out a refrigeration unit mode, that operator shall be responsible to collect or request disposal of the relevant manuals from the affected vesselís library.

e) Replacement of any of the manuals onboard a vessel shall be as per the charter party.

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:
  1. 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....

  2. 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. ....

  3. 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. ....

  4. 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. .....

  5. 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.....

  6. 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......

  7. 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. ....

  8. 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. ....

Container handling additional guideline:

Containership cargo stowage and planning

Stacking Weights Restrictions

Lashing strength calculation

Dangerous goods stowage and segregation

Reefer Container Stowage

Out of Gauge Container Stowage

Special Container Stowage

20 or 40 or 45 feet Compulsory Stowage Locations

Irregular Stowage of Containers

Over-stow of Containers

Hatch Cover Clearance (High cube containers Under Deck )

Other matters regarding cargo stowage as necessary

How to load maximum number 20 feet container on deck ?

What are the extra precaution should be taken prior loading a 45 feet container on deck ?

Container damage in ''2 in 1'' cargo Operation

Modern containership & loading of various container types

How to load containers coming in different forms/sizes

Our additional pages contain somewhat larger lists of resources where you can find useful informations

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Reefer cargo handling Troubleshoot and countermeasures
DG cargo handling Procedures & Guidelines
Safety in engine room Standard procedures
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