The use of brine trap - dsdafadGdgdsdgadgaDGFAF PDF

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1. The use of brine trap. The brine in the trap forms an effective seal against ingress of warm air, and it will not freeze, preventing the drain from removing water from the compartment. The most important consideration when stowing general in refrigerated chambers is that of avoiding damage to insulation, air-trucking and gratings. The brine traps serve a dual purpose they prevent the cold air from reaching the bilges and thus freezing out the water in the pipes and also they prevent the bad odour from the bilges reaching the cold chambers. If the vessel is fitted with brine-pipes the side baffle boards (which keep the cargo clear of the pipes) should be removed and the pipes wiped clean. If fitted with the cold air circulation system, air ducts should be cleaned, this is particularly important if a dusty cargo has been carried previously. Brine is water saturated or strongly impregnated with salt in which salt is evaporated; it is used as a cooling agent. Brine trapped in compartment drain line must be heated especially when loading frozen products in the holds in order for the excess water to run freely into the bilges. If brine drain is frozen, the tendency of the water is to return into the compartment that causes malfunction or reduction of cooling effect.  Brine pipes are provided to seal the drain pipes from tween deck to bilges in order to allow only one drain passage from tween deck to bilges.  To stop any backflow of gasses or foul odours from bilges to cargo space.  They should be checked and topped up to prevent cold air to entering the bilges and freezing them or odour from reaching refrigerated compartment. 2. Principle of refrigeration? Refrigeration basic principle named after two scientists, James Prescott Joule and William Thompson. This procedure is called a throttling process or Joule-Thomson. The process where a gas or liquid change its temperature when it is forced through an expansion valve or capillary tube in an insulated system where no ambient heat transfer. At STP (standard temperature and pressure) , all

gases cool upon expansion by the Joule–Thomson process with the exception helium, neon and hydrogen gases. Refrigeration basic principle applies on all system whether it's the smallest water cooler to largest walk-in freezer that ever built. Freon gas or the refrigerant absorbs heat inside the area to be cooled in the evaporator unit and transfers that heat to the refrigerator's condenser at exterior . The Refrigeration basic principle is that with the aid of a heat pump, the refrigerant is being compressed to the condenser and capillary tube thus increasing its temperature (50-60°C) and pressure (750 kPa) in the refrigerator being cooled down by the condensing unit to 32°C depending the existing ambient temperature. Upon entering the evaporator unit the gas expanded and vaporized due to sudden enlargement of the evaporator tube cross-section eventually dropping its pressure to almost atmospheric value (120 kPa) and temperature from 32°C to -24°C. Heat absorption takes place from the evaporator and being pump-out by a heat pump to the condenser where being transformed from cool vapor to liquid state with higher temperature and pressure thus completing the heat transfer cycle. Theoretically, after the cycle the amount of refrigerant will remain contained in the system. When leakage occurs in the closed circuit then efficiency of the refrigerator will gradually diminished till it stops cooling. By then, it requires servicing to be done by a qualified technician to locate its leakage or parts that are not functioning properly. Why refrigerate? Refrigeration is essentially the removal of heat through the process of evaporation. 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. Humidity is also a very important factor in the conservation of many fruits and vegetables. By shipping products in our Controlled Atmosphere containers, the humidity inside the containers can be increased, thus minimizing any weight loss in the fresh produce. Temperature is not the only important part of the equation… but it is the key element to successful refrigerated transport.

Technically speaking, the internal biological and chemical processes of fresh produce, such as respiration, will continue after harvesting. This means that the product absorbs oxygen (O2) and releases carbon dioxide (CO2) and ethylene (C2H4). This is a process that generates heat. Lowering the temperature reduces the respiration, and consequently the heat, considerably. Therefore, temperature is the most important factor when prolonging the practical shelf life. As high concentrations of CO2 and ethylene can deteriorate the commodities, these gases must be removed and replaced with fresh air through the ventilation system. Ethylene production is especially high in fresh produce such as apples, peaches, apricots, avocados and pears. Many perishable cargoes are carried in refrigerated compartments on dry cargo ships, and there are an appreciable number of vessels specifically designed for carrying refrigerated cargo only. Stowage of refrigerated cargo Chilled meat cargo is hung from the strengthened deck stiffening members, and the tween deck height is arranged to provide space below the hung carcasses for the circulation of air. Frozen meat is stacked in the holds of the ship. Fruits and vegetables are stowed in a manner which permits an adequate flow of air to be maintained around the crates, etc. Refrigeration systems on board Brine made by dissolving calcium chloride in fresh water will have a freezing point well below the desired temperatures of the refrigerated compartments. Cold brine may be pumped at controlled rates to give the correct working temperature, and it is led from the evaporator of the refrigerating machine to pipes at the top of the cold compartment. The brine absorbs heat from the compartments and returns to the evaporator where it is again cooled and recirculated. Air must be continually circulated where fruit is carried to disperse any pockets of carbon dioxide gas given off by the ripening fruit. The brine is then led into grid boxes and air drawn from the bottom of the compartments

by fans is blown over the brine grids into the compartments via trucking arranged along the ceiling.

As the steel hull structure is an excellent conductor of heat, some form of insulation must be provided at the boundaries of the refrigerated compartments if the desired temperatures are to be maintained economically. Cork, glass fiber, and various foam plastics in sheet or granulated form may be used for insulating purpose, also air spaces which are less efficient. Glass fiber is often used in modern ships as it has a number of advantages over the other materials; for example, it is extremely light, vermin-proof, and fire-resistant, and it will not absorb moisture. On the decks and particularly at the tank top the insulation must often be load-bearing material, and cork might be preferred, but fiberglass can be supported by tongue and grooved board linings and wood bearers. 3. Purpose of compartment temperature recording?

Reefer containers require special care after they are loaded on board ship. These containers need to be supplied with power, monitored closely for proper function and repaired as required in case of malfunction. The article here is about procedures and guidelines on reefer cargo Temperature Recording

Reefer machinery

A Part low 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. These charts should always carry the following endorsements:         

>Name of Vessel > Voyage Number > Container Number > Temperature Setting > Load Port > Discharge Port > Date of Stuffing/Change > Ventilators: Closed/Open (degrees) > Humidity Controls (HMC) (percentage) Data logger recorders may monitor both 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 of the container in port). The information is more comprehensive and accurate than indicated by a part low 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) it is important that the sensing head (in this case the bulb) is 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 extraneous 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 carefully insert the thermometer. Metal sheathed (spear) thermometers enable proper penetration but require a longer time to achieve the true 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 and 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.

Reefer

containers require special care after they are loaded on board ship. These

containers need to be supplied with power, monitored closely for proper function and repaired as required in case of malfunction. The article here is about procedures and guidelines on reefer cargo maintaining records. Temperature of the air which is drawn off from the refrigerated hold/container is called "Return air temperature". It is important to maintain the return air temperature during refrigeration. Maintaining proper records is as important as the actual performance of the job itself. In case of any cargo damage and claims, it is most important to prove that the Due Diligence was exercised by the master / vessel from the time the container was loaded on board until the time it was discharged. Therefore, the master should keep all records to prove due diligence on board, and send them to the company immediately in case they are requested: Item Records i) Supply of electric power within reasonable time after loading reefer containers Loading check lists including the loading / plug-in times and temperatures should be maintained. ii) Monitoring the digital & chart temperatures of all reefer containers at least twice a day. Daily reefer container temperature check lists should be maintained, and printouts from monitoring unit should be preserved iii) Notifying booking line and/or agent immediately in case of malfunction File of Reefer Unit Trouble Report should be maintained iv) Keeping enough spare parts in good order Record of regular inventories, and communication to booking lines for consumption and/or supply receipts...