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896 CHAPTER 59 1965 Guide And Data Book The cabinet may be constructed of wood, steel, aluminum, or stainless steeL Doors can be binged or sliding and either solid or glased. Fig. 1 indicates the approximate loads (by cabinet sise) for reach-in refrigerators with a 90 F ambient temperature. . Reach-in refrigerators are also built for low-temperature storage and for process applications, such as for bakeries. The meats, produce, dairy products, poultry, smoked meats, eggs, and many other foods. Temperatures required in the case for these products are shown in Table 1. Evaporators in open self-service cases usually are the forcedair type, although the natural convection type may be used. Defrosting is accomplished by automatic defrost systems or compressor off-time. low-temperature cabinets may use refrigerated plate coils or'forced-air-finned-tube evaporators with automatic defrost Display Cases for tow Temperatures systems. - .j. - -- -* - - *i ^ -Service-type lowrtemperature cases may have hinged or ;' sliding doors on .the'fop of the cabinet,'or hinged doors at the back. When top doors of the sliding type are used, these often ""areglazed for tfre'display.of products stored and to allow for "customer service.' * ' The refrigeration of these cases may be accomplished by Opiate coils, liner colls or-forced-air systems which incorporate automatic defrost means of some type. Open self-service cases are available as single-duty, double duty, wall, island, or multiple-shelf wall type. The most ' popular type of refrigeration system for these cases is the forced-air type with an automatic defrost system. - ' In many installations, either reach-in or walk-in type stor age cabiaets are used in conjunction with dispensing cabinets and are used as a reservoir to supply the dispensing cabinets. The'refrigeration'ih such storage cabinets can be either plate type evaporators' or finned evaporators using an-automatic defrost system. ' . '', ` Table. 2 shows typical condensing unit sizesr for' multiple sections of open cases for 75and 90 F ambient conditions. It should be noted that these are general recommendations'and fig. 1 .... Approximate Refrigeration Load for - .Reach-In Cabinets that the manufacturer's recommendations should be followed for any specific case. INSULATION Display Cases for Normal Temperatures "The two general types of display cases are the service type and the open self-service type. Either.of these types may be refrigerated by a natural convection or forced-air system. The service type or closed case may be either the single-duty or double-duty type. The single-duty case is refrigerated in the display-section;o.nly, and the.unrefrigerated base.is left open from the rear of the case. The double-duty case is refrigerated in both the display and base sections. When the single-duty case is cooled by natural convection, a finned-tube evaporator is usually located in the top of the case, ahd with abare-tube coil is located near the bottomjrf the refrigerated section. A drain pan is installed beneath'the finnad coil, and the bottom of the case is pitched toward a' drain outlet. FLg.: 2 shows a cross-section view of thbrgeheral, arrangement. .... - Fig. 3 indicates the approximate loads on top display, closed! type, meat cases for-75 and 90 F'ambient-tempera tures. ' ' . ' 1J The' double-duty display case uses a' top coil arrangement in the display section similar to that used in the single-duty, or top display case. The coil for the base compartment is a bare-tube or finned coil located along the front wall of the or beneath -the main shelf in a horizontal position., Fig. 4 shows a cross-section view of this coil arrangement; Several types of open display cases sire built for normal tem perature storage. Single-deck cases can be supplied single-' or double-duty. The double-duty type can be supplied with doors in the front or rear of the base compartment. In addition to the single-deck cases, multiple-deck cases-are available .with two, three, or four shelves. "j. Products displayed in these cases include^ fresh and cold Insulation in commercial refrigerators may be of the loose fill, batt, rigid, or semi-rigid types, depending on its function in the cabinet. In some locations in a cabinet, the insulation must also serve:as a supporting member. Such cabinets have a oombination of rigid and batt type insulation. . ' Proper Riding against moisture penetration may be ac complished by using a vapor-proof insulating paper sealed with mastic,.or: by, sealing all joints on the outer shell of a Commercial Refrigerators and Dispensing Cabinets 897. metal 'cabinet with a water-proof, odorless mastic. Many foam-type insulating materials form their own vapor barrier as the result of the nature ahd cellular structure of the ma terial- . The thickness of insulation required depends upon the tem perature' maintained within the cabinet. General practice has been to insulate with 3 or 4 in. of insulation in cabinets designed for temperatures of from 35 to 40 F, and to use 4 to 6 in. of insulation in those cabinets designed for temperatures of 0 F or lower. - fig. 3 .... Approximate Refrigeration Load for Singie. . Duty Service-Type Meat Display Cose struction lends itself readily to mass-production methods and,' more particularly, to hermetical scaling of the cabinets.': Commercial cabinets for market installations are usually of the endless construction in order to form a continuous dis play as the fixtures are joined. The use of steel construction in . these cabinets is almost a -necessity, of the elose tolerances in dimensions required to join the fixtures. Separate' end sections are provided for the first and last units in a eon- tinuous display arrangement. Methods of joining self-service cases vary to-some extent, but cases usually are either bolted or wedged together. " In open'self-service cases condensation may occur on metal parts located - near the top of - the refrigerated zone. To eliminate this condensation it is necessary to apply heat to: this area. This may be done by applying heater wire directly to the metal, or by applying some type of heater element to the under side of the metal.- The wattage required 'for this heater is best determined by test of the particular cabinet un der high humidity conditions. Typical heater requirements are shown in Table 3. Heaters are used around doors in reach-in or walk-in type cabinets, and the heater element or wire is either attached to the metal around the opening or imbedded in the breaker ma terial REFRIGERATION EQUIPMENT Evaporators Evaporators used in commercial refrigerators may be: (1) finned-tube, (2) bare-tube, (3) plate, or (4) icemaker type. The finned-tube type is the most common, andusualiy con sists of aluminum fins mechanically bonded to copper tubes.. Fin spacing depends upon the particular application but .For further information on insulation of commercial re frigerators, refer to the section Domestic and Commercial Refrigerators in Chapter 22. CABINET CONSTRUCTION . " Framing used in commercial fixtures may be metal, or wood which has,been treated with a waterproofing materia) Wood is also used in the framing of cooler sections and as supporting members or thermal breakers in metal cabinets. Welded steel construction is more common than wood in the, construction of portable 'commercial cabinets. .Such cou- Table 3 .... Typical Requirements for Heaters to Prevent Condensation Type of Com Meat Frozen Food Ice Cream Watts per Foot of length ' 20 16 12.5 26 27 35 35 27 35 Average - 15 31 33 ToWe. 2 ....Typical Condensing Unit'Sizes (Horsepower)' . for Multiple Sections of Open-Type Cases length Ft ,8 24 36 fee Fftjfi Multiple Food Produce Shelf Meat* Dairy Ambient Temp--F 75 90 75 90 75 90 75 90 75 90 1 IK lK 2 ftIK 3 333 335 K H K M IK IK Yt 1 1 22 I IK i IK 2 3 IK 2 i IK 3 3 35 5. 5 5 7K IK 2 ----2 3 5., ft- -- , -- 2 3 5. m --3 3 IK 2 IK 2 23 23 3 5. 5 __ __ ----