Three factors affect the rate at which frost and ice accumulate on refrigerator coils: (1) door traffic, (2) excessive temperature difference between the coils and the box, and (3) moisture from the stored materials. In each case the buildup can be reduced by properly planned and executed breakout procedures. Measures discussed in the following paragraphs may be used to prevent excessive icing of coils.

Door Traffic

Breakouts should be planned for a full day's requirements. All messes must draw their frozen subsistence items at a predetermined time, usually in the morning. Any items withdrawn at this single daily breakout from the freeze box, if not intended for immediate use, should be stored temporarily in the chill box.

This one breakout per day should be strictly enforced. With a little planning on the part of the various messes, it should not be too difficult. In this way, the reefer temperature will remain constant and excessive icing from too much door traffic will be kept to a minimum.

Temperature Controls

A difference in the temperature of the refrigerated spaces and the refrigeration coils will cause vapor to form on the coils and the refrigeration coils will turn the vapor into ice. This ice formation continues until the temperatures of the coils and the refrigerated spaces equalize.

The temperatures of the coils and the refrigerated spaces are likely to differ most during the period when the freeze box is being restocked. The higher temperature of the food items being stored will cause a rise in temperature in the refrigerated space and produce vapors. There is no way to prevent this condition, since the work of storing must go on. However, once the storage has been completed, the box should remain closed until the normal temperature level of the freeze box has been reached.

Air Circulation

Proper storage and adequate air circulation help prevent excessive ice formation. Continuous circulation by electric blowers is necessary at all times. Storage arrangements should allow free circulation of air throughout the box.

Adequate aisles and overhead space should be provided to permit the free circulation of air from the blowers. Blowers should be inspected each day to ensure proper operation.  Any malfunction in the circulating unit should be reported to the duty engineer immediately.

Defrosting and Cleaning Refrigerators

The refrigeration coils and units in cold storage spaces should be defrosted as often as possible. A layer of frost or ice 1/4 or more inches thick will reduce the efficiency of the refrigeration system and may result in overloading the compressors. Always consult the engineering department regarding the defrosting of the refrigeration system.

Most refrigeration units are so equipped that hot gas can be run through the cooling coil to melt the ice. Then the bulkheads, the overhead, and the deck remain cold because of the speed with which the coils are defrosted, and there is no necessity for moving the feud. This method of defrosting should be used on all ships equipped with such a hot gas capability, since refrigeration is not interrupted.

If your cold storage plant is not of this type, it will be necessary to consult with the engineering department to determine other methods of defrosting. And, of course, you should never use an ice pick or a sharp tool to pick ice from the coils.

Once defrosting is completed by a nonhot gas method, scrub and wash the box thoroughly with hot soapy water. Rinse, dry, and air the box and return the food to its place immediately.

Refrigerator Log

A refrigerator (or reefer) log must be maintained by the person responsible for the refrigerated spaces. Temperature readings must be taken twice daily and at other times as necessary. The reefer log is presented daily to the leading MS and the FSO for review and initialing. Temperature irregularities must be reported to the leading MS and the FSO immediately.