types-one for bulk storage of fresh meats, dairy products, vegetables, and fruits requiring a temperature from 35F to 38F and the other for the storage of frozen food at temperatures of 10^o F or below. The 35F to 38F refrigerators are built and shipped in sections and assembled at the location they are installed. They can be taken apart, moved, and reassembled in another area if needed. Standard-size coolers can be from 24 square feet up to 120 square feet in floor area. A walk-in refrigerator with reach-in doors is shown in figure 6-37.

The exterior and interiors of these units are normally galvanized steel or aluminum. Vinyl, porcelain, and stainless steel are also used. Most walk-in refrigerators use rigid polyurethane board, batten, or foamed insulation between the inner and outer walls. For storage temperatures between 35F to 40F, 3 to 4 inches of insulation is generally used. For low-temperature applications, 5 inches or more of insulation is used. These refrigerators are equipped with meat racks and hooks to store meat carcasses. Walk-in refrigerators also have a lighting system inside the refrigerator compartment. Most systems have the compressor and condenser outside the main structure and use either a wall-mounted forced-air or gravity-type evaporator that is separated from the main part of the cabinet interior by a vertical baffle.

The operation of the walk-in refrigerator is similar to that of the reach-in units. The evaporator must have

Figure 6-37. - A walk-in refrigerator with reach-in doors.

sufficient capacity (Btu per hour) to handle the heat load from infiltration and product load.

DOMESTIC REFRIGERATORS

Domestic refrigerators are used in most facilities on a Navy installation. Most domestic refrigerators are of two types - either a single door fresh food refrigerator or a two-door refrigerator-freezer combination, with the freezer compartment on the top portion of the cabinet, or a vertically split cabinet (side-by-side), with the freezer compartment on the left side of the cabinet. They are completely self-contained units and are easy to install. Most refrigerators use R-22 refrigerant, normally maintaining temperatures of 0F in the freezer compartment and about 35F to 45F in the refrigerator compartment. The Utilitiesman must be able to perform various duties in the maintenance and repair of domestic refrigerators, water coolers, and ice machines at Navy activities. This section provides information to aid you in handling some of the more common types of troubles. But let us remind you that the information given here is intended as a general guide and should, therefore, be used with the manufacturer's detailed instructions. For troubleshooting guidance, see table Y in appendix II at the back of this TRAMAN.

Single Door Fresh Food Refrigerator

A single door fresh food refrigerator (fig. 6-38) consists of an evaporator placed either across the top or in one of the upper corners of the cabinet. The

Figure 6-38. - Single door fresh food refrigerator.