Document NjVLjJkxLRGqRJjER7XZ0nXD

894 CHAPTER 58 secured from various sources and represent approximate value indexes which must be tempered by judgment and experience for specific job conditions. The values are relative costs, not dollar costs. The installed cost of 2J-in. Type K copper and Schedule 40 steel pipe has been assigned a value of 1.0. Ma terial costs are generally higher for copper than for steel, but the installation costs are less. From Table 21, it is apparent that, for nominal sizes up to 2| in., the use of copper tube is usually more economical, but for sizes over 3 in., the use of steel pipe is usually more eco nomical! However, job conditions, the experience of the men actually installing the piping, design limitations such as cor rosion, ambient temperature, availability of materials, and other factors may supereede simple cost considerations. REFERENCES 1 American Standard Code for Pressure Piping ' (American Standards Association, ASA &31.1, 1955, and Addenda B3I.la, 1965 Guide And Data Book 1983).- Refrigeration.Piping (American Standards Association, ASA B31.5, 1962, and Addenda B31.5a, 1963). * API Specification 6L for Line Pipe (American Petroleum Institute). * Standard Manual on Pipe Wddxnq (Heating, Piping and Air Conditioning Contractors National Association, 1951, 2nd ed.). Welding Handbook (American Welding Society, 1942). * ASME rawer Boiler Code (American Society of'Mechanical Engineers). 1 Marine Engineering Regulation* of the Coast Guard (Amer ican Bureau of Shipping). Welding {General Specifications for Inspection of Material, Appendix VII, U. 8. Navy). General-- for vessels of the O. S. Navy (Specifications for Welding, Ap pendix 5, Part L Bureau of Snips, April 1940). ' The Barco "Off-Set" Method (Barco Manufacturing Company, Barrington,-Illinois). r? ' 1 Sabin.Crocker: Piping. Handbook. (McGraw-Hill Book,Co., New Ybrk)!E.'A. Wert, 8. Smith.'ana,E. T. Cope: A Manual for Ihe Dtsign of Piping for Flexibuityby the Vse of Graphs (The Detroit Edison Company). ->T: ' * American Standard Safety Code for Mechanical Refrigeration (American Standards Association, ASA B9.1, 1964). CHAPTER 59 COMMERCIAL REFRIGERATORS AND DISPENSING CABINETS Waft-fn Storage Cooler*, Reocfi-fn Cahmefx, Normal and low Temperature Display Cases, Cafwnef Construction, Insulation, Evaporators, Defrosting, Controls, Condensers and Cooling Towers OMMERCIAL refrigeration cabinets - can -be divided - coolers are the forced-air and natural convection, (gravity) C into three general classifications: (1) merchandising die-, types. Some market operators want meat cooler-tempera play equipment, (2) storage equipment, and (3) processing.tures of 28.to 32 F. In such coolers, an automatic defrost ' equipment. A further divirion of each of these classifications system is usually required. can be made according to temperatures: (1) for tempera tures above freezing, and (2) for temperatures below freezing. In each of the three general types of cabinets, the products to be stored determines, to a great extent, the general design of tiie cabinet and its refrigeration system. However, in each, design, consideration must be given to temperature, air cir culation, and air moisture content. Table 1 lists the recommended temperatures for retail storage. Reach-In Cabinets The reach-in refrigerator, equipped with hinged or sliding glazed doors, may be used as a self-service cabinet for dairy products or beverages. Solid door models provide additional storage space. The range of sizes of commercial reach-in cabinets is from approximately 16 cu ft to 100 cu ft capacity or more. Some models are self-contained while others are installed with re STORAGE CABINETS Walk-In Coolers . mote condensing units. - Evaporators used in these cabinets are forced-air, natural convection, or ice-cube maker types, depending' upon the The unitary walk-in storage cooler is of sectional construc application or use for. which.the cabinets are intended. - tion, with wall, ceiling and floor sections which must be joined and fastened at the time of installation. The material used in the construction of the cooler sections may be' wood or metal. However, the trend in supermarket installations seems to favor metal, both exterior and interior. Table 1 .... Recommended Temperatures for - Retail Storage - In many coolers, both exterior and interior surfaces are covered with enamel finish. . Wood used on the interior of a cooler must be an odorless . Type of Fixture Average fernp. F Mmaua., Mcx/mmb type, such as spruce, maple, fir, etc. Interior wood panels are usually given a finish.' Many walk-in coolers constructed to maintain 35 to 40 F temperatures are being installed without insulated floor sec tions. In some instannas, an inmilftted floor is built into the Walk-In Cooler (Unfrozen Food) Walk-In Cooler (Frozen Food) Reacb-In Refrigerator Single-Duty Meat Case (Closed) Single-Duty Meat Case (Open) 35 -10 35 35 28 . 42- . . ,: 0 .45 ... ' 42 ` 42 . y market floor at the time of the floor construction, while in other installations, the cooler is erected upon the uninsulated slab. In computing the refrigeration load for a cooler installed upon an uninsulated floor, an allowance must be made for the extra heat leakage. Douhle-Dutv Meat Display Case (Closed) Double-Duty Meat Display Case (Open) Vegetable Refrigerator or Case (Closed) Vegetable Refrigerator or Case (Open) Dairy Refrigerator (Closed) 35 - .. 42. s 28 ' 42 , 35 48 ' ' 35 "55 35 '42 ' Walk-in coolers which serve a dual purpose of storage and display are equipped with either sliding or binged glass doors on the front. These door sections often ale a prefabricated assembly which is set into a door opening within the front of tire cooler. Allowances must be made in computing the re frigeration load for the extra service load through these glass doors. Evaporators commonly used in normal temperature Tbs ooail rMpo&^hiSV for this ebspta b >iiiguft1 to TC Cooupo* ea) Pood Stonge *ad DttptMins-Eqotptnwtt.' Dairy Refrigerator (Open) Baker's Dough Retarder Florist's Display Refrigerator Florist's Storage Cooler Frozen Food Cabinet (Cioaed) Frozen Food Cabinet (Open) Candy Case Candy Case (Frozen) ' -' ' Ice Cream Cabinet or Case (Closed)* Ice Cream Cabinet or Case (Open) Bottled Beverage Cooler 35 35 40 38 - 5. -10 45 40 ; 50 : 45 ' 0 5 65: - 70 ' o - ."TO:! " -- ,5 ... -20 0 * 35 L . ' 42 895