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Vyde tn m R-ta74 ¥ Bo P88 Fa A . fea Po Tie il : t a ‘ caielias ietsen an iH Het Vihwae | ert eteee Rcatypsaeh harsh ene tt el tee ern a? hand wet Sh eans SALAM 18 oc ; tt Ne re Wh ee Wh wing ve wey n peas Se a ee iat a : UNITED STATES DEPARTMENT OF AGRICULTURE LIBRARY l Ags4Mr 889118 No, 130-144 BOOK NUMBER ss Tob ie, f ia Spe a Ris hy ii a ie i A ie ji oY ny Pie ) ; . = = — — i ~ ; 2 - i] = 4 oe Wa had teh mia Me Ste if aa j fe VU Behe Wye C. aeae ee ; ; . 5 al he pes a 5 ue t - a yo A ne i i i a 2 a ae 1 nK : aay : cs : a : - 7 ' i ? { Ys ete 4 ih >A 1 ; | Mere x 7 a, € wa ae =) ats i 7 2 yo ¢ 7 Hy 70 : ‘ } i : ad * . « 7 a." 7 | 7 C LAT * hi raat U ] Sy ; - A i ‘ r t i , : ‘% BA A : i. 2a ay { i) Ve 7 = 7 : €: F f : 1s ~~ VE cn > 2 ; y ; j io a ee ‘i ’ - . a i iw Wy } 4s 1a : : ’ oe, * A ‘ - OF if] fe ; ' és a L Bu ip 5 Pe . - = 7 iy ‘ y av M { oon ” vo io 1, Ta. , oe = n Re - le cy : aa ih ve : 7a ve" 3 r ai uh a aT ' vies , ‘ , yt tog, oan Ce b Pete a oe . ay 7 wry 7 = ae, be vine b ; = = Awe a Bans : ; . ~ 7 - t UJ oY f 3 & 1 iS a “ay - 7 i st ® => ! . BAY) 4 ty ’ a i { : i nH Me } - i ° Be) ao a) j d j m - ' : =A Fi : : j as } ' ¥’y i i UJ ; n : ae a fi to s ri 7 i fini a: Cree x Fi : : \ Paes : i j H ne, ays i ‘ if ap : ‘ime ae | ; Pali ; rT at i CA 7 Ba; - i] is i oe 7 Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. The Effect of APPLE HANDLING METHODS on Storage Space Utilization UNITED STATES DEPARTMENT OF AGRICULTURE Agricultural Marketing Service Marketing Research Division Washington, D. C. MARKETING RESEARCH REPORT NO. 130 July 1956 This is the fourth of five reports to be published by the Agri- cultural Marketing Service from data submitted by the Washington State Apple Commission in fulfillment of its contract with the U.S. Department of Agriculture. The first three reports are Marketing Research Report No. 49, "Apple Handling Methods and Equipment in Pacific Northwest Apple Packing and Storage Houses, '' Market- ing Research Report No. 68, "Innovations in Apple Handling Meth- ods and Equipment,'' and Marketing Research Report No. 71, "Handling Empty Apple Boxes in Pacific Northwest Apple Packing and Storage Houses." The fifth report in this series is expected to cover plantwide materials-handling costs. After this report is issued, a summary is planned. "Methods. and Costs of Loading Apples in the Orchard in the Pacific Northwest, '' Marketing Research Report No. 55, published by the Agricultural Research Service of the Department in January 1954, summarizes another phase of the study. Some of the results of this research are now available in sum- mary form through the U.S. Department of Agriculture film en- titled ''Apple Handling Methods.'' A print of this film may be obtained on a loan basis from: Visual Aids Service Agricultural Extension Service University of Illinois College of Agriculture 713 1/2 South Wright Street Cornell University Champaign, Illinois Ithaca, New York Agricultural Extension Service Colorado A & M College Ft. Collins, Colorado ‘ 55 J ? ™ A 445 4 i gel, Vv ca act RVG OE il PREFACE 889118 The research which is the basis for this report was conducted by the former re- search department of the Washington State Apple Commission under a contract with the United States Department of Agriculture. This contract was administered by William H. Elliott, head, Handling and Facilities Research Section, Transportation and Facilities Branch, Marketing Research Division, Agricultural Marketing Service. The study was made under authority of the Agricultural Marketing Act of 1946. The authors gratefully acknowledge the assistance of Frederick C. Winter, asso- ciate professor of industrial engineering, Columbia University, and consulting industrial engineer, Transportation and Facilities Branch, and Joseph F. Herrick, Jr., agricul- tural economist, also with the Transportation and Facilities Branch, for reviewing the manuscript and making many helpful suggestions. The authors express their appreciation to the operators of apple storage and packing plants in the State of Washington who made their facilities available and otherwise gave invaluable assistance. Credit is due Earl W. Carlsen, who supervised the research, and the other em- ployees of the research department, Washington State Apple Commission, who gave valuable service in assembling and analyzing data and preparing the report, as follows: Raoul S. Duerden, William C. Dower, Walter E. Nelson, and Clarence H. Engberg. CONTENTS Page RRPRL YN ASA Vabi ge viot Seu de me Pea) eat ates cl che 6 Farah tes eres be Sere ialny dd oi eps bd eee (cus ei noe, spake tela geuere® sue ga s iv Batelco moundsOtethesStud yas oi ssi 5 taps ite 7. goes ign Mos colic lo loudahishs, ct wp 2D ose ieub ohare Ciel Goud eee Be « ] Bactorsosattecting Storage spac esti Zab Omics igi. cci resis 0 vvey ede Me co se) whe 6Y' 5h ofpore Wh obi 0 sud fo hazel ey ante 2 Enc Srpet eee. <5 eet AIS chek WISP he. a PENIS «Ect etiio es eiatE amie labs Sue Sel Bhs Sew Stare a! oct eevee 2 BARIESIMCMES CA Cline they oa Peeled. acces cg) Se AS 5G ia, a) oie, (Shoe PUG Vance oto apa sa S "of ale outs Jats ahatioms dees 4 stra Cllatila SUB I © 1D lait ghee) SF sack 0 tes, esis uicics Bot loties eke BUist s) aos, baal st o/s Weeds’, ¢, “sale? Eive, > ehsr'e Swatsiete aval oss 6 ReLmige natvonvandsa ra citcitlation_ equi pmaent sir .c. fist 2 lo. feiss erst. o, 3,2 6s auees id eerie shee 6 EXOISE SMa ONSET: Siig ois eheists orcs Wee be oS co suerkasio che Ly She aoc qe Tene ie de yeh seek, os thanete whee oa 8s te 7 Floor capacity of a conventional bay when using specified types of equipment...... 8 Storage space utilized in rooms of specified designs when using different types of PUTTING TH bi neon oie ctty of obs APIS cpl R Shane: af ads focsch sch sc Ls oA th acts WSL whol egos de ciaeis seus ge wel le alts 60 0 ss 11 @onventional (storage: room: 50, by SO: by 13.) (2 fects ae cud visio ue him oho Riel eee ow aye © | Sonventional storage, room:50) by 11 0-by J 2.1/2: feet so. we cine io Sa cide kiss brass 0 13 Mode rnaEstor age: FOOMms6 Oz Dyi9 Osby 20 -16e bok ic 4. cams fier Seid: wie, sds he vege, aucuenelte at's, © ce oye “s 13 Effect on storage revenue of changing from one type of equipment to another...... 16 For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D.C. - Price 15 cents lii SUMMARY Storage space utilization is an important consideration to the operators of apple storages because it affects their returns for performing all operations in connection with storing and packing apples. Different types of materials-handling equipment which handle unit loads of different sizes govern to a great extent the volume of apples that can be stored in a given space. In this study three sizes of storage rooms were selected. Two of these rooms are of conventional design; they are typical of many found in older multiple-story plants in which clamp-type 2-wheel hand trucks are used for performing handling operations. One room is of modern design, suited for industrial trucks. Important variables considered in determining the amount of storage space that could be utilized in these rooms are: (1) Size of unit load; (2) aisle space; (3) stacking height; (4) type and kind of refrigeration; (5) air circulation used; and (6) spacing and size of posts and girders. In storage rooms with relatively low ceilings and supporting columns set on 16-foot centers, more piling space can be utilized by use of clamp-type 2-wheel hand trucks than by use of industrial lift trucks. However, in rooms that have relatively high ceilings and roofs supported by trusses rather than columns, a substantially greater number of boxes can be stored by industrial lift trucks than by clamp-type 2-wheel hand trucks, even though the industrial lift trucks need more operating space. The following tabula- tion indicates the range in the net storage capacities of three storage rooms when speci- fied types of equipment are used and when boxes are stacked at heights conforming to present industry practices: When a clamp-type 2-wheel hand truck is used in a room measuring 50 x 80 x 13 1/2 feet, the boxes are stacked 12 high and the net storage capacity of the room is 21, 400 boxes. When a 48-box forklift truck is used in the same room, the boxes are stacked 1] high and the net storage capacity is only 15,000 boxes. Using a 2-wheel hand truck in a room measuring 50 x 110 x 12 1/2 feet (boxes stacked 12 high) the net storage capacity would be 28, 850 boxes; this compares with 15, 300 boxes by use of 48-box industrial forklift truck (boxes stacked 11 high). When a clamp-type 2-wheel hand truck is used in a storage room of modern design, measuring 80 x 90 x 20 feet, the net storage capacity--boxes stacked 12 high--of the room is 36,000 boxes, or 37 percent less than the net capacity of 57,000 boxes when using 24- or 36-box industrial clamp lift trucks and 36-box industrial forklift truck. A storage plant operator contemplating a change in handling method and equipment should consider all the advantages and disadvantages as well as the effect on total gross revenue. Some of the advantages of the more mechanized methods in use today include: (1) Smaller labor costs, (2) smaller crews, and (3) less bruising and damage to fruit. Some of the disadvantages are: (1) Greater capital investment and (2) a substantial re- duction in usable storage space. A decision to change from one handling method to another should not be made solely on the basis of gross revenue considerations. iv THE EFFECT OF APPLE HANDLING METHODS ON STORAGE SPACE UTILIZATION | By D. Loyd Hunter, industrial engineer, and Francis Kafer, research analyst* Washington State Apple Commission and Charles H. Meyer, agricultural economist Transportation and Facilities Branch Marketing Research Division Agricultural Marketing Service BACKGROUND OF THE STUDY Most of the older apple packing and storage houses in use in the Pacific Northwest were designed for the use of certain types of materials-handling equipment. Because of ‘their design, the adoption and efficient use of newer types of materials-handling equip- ‘ment has created problems for these houses both in the movement of products between floors and the utilization of storage space. The modern one-story apple storage plant ‘has little resemblance to plants constructed 20 or 25 years ago. The old-type multi- storied plant usually was designed in terms of square feet of floor space rather than cubic feet of stacking space and for extensive manual handling rather than for the effi- cient use of modern materials-handling equipment. The introduction of modern equipment in these houses in recent years has hada decided impact on the utilization of space in cold storage rooms. Today, boxes of apples are moved into, within, and out of storage rooms by many types of mechanical equip- ment. Each type or combination of types of equipment affects the number of boxes that ‘can be stored in a given area because each requires different aisle widths and other operating space. Moreover, the heights to which boxes can be stacked and the ability | to use space in confined areas, around columns, and under coils vary with different types of equipment. The use of some types of equipment also results in more airspace around boxes than is required for other types. This spacing not only affects space utili- zation, it also affects the air circulation around the boxes, which in turn has a bearing on the maintenance of optimum storage conditions for the fruit. Utilization of storage space also is influenced by the size of unit loads, which vary from single stacks consisting of 5 or 6 boxes to as many as eight 6-high stacks, ora total of 48 boxes, and on the height to which unit loads are stacked. A small unit load iS more maneuverable and enables irregular space to be filled more readily, whereas ja large unit load may result in loss of space, or require manual methods for adjustments of unit loads to fit irregular space. Because of their maneuverability, some of the older types of materials-handling equipment permit more effective use of space in the old-type |storage plants than some of the newer types of equipment. Sizes and shapes of containers used for apple storage also influence the utilization of storage space. However, in the Pacific Northwest, fruit is stored in the standard Northwest apple box. To some extent this standardization simplifies the space utilization problem. The outside dimensions of the standard wooden box are as follows: Width, 12 inches; depth, 11 inches; and length, 19 WA inches. After it is packed, the standard apple \box has a bulge on the top and bottom which adds about 2 inches to the depth, so that it measures roughly 12 inches by 13 inches by 19 1/2 inches. Thus, the space required to store a packed box is slightly greater than that for a box of loose fruit. Some growers store apples in field boxes which have external dimensions identical to the standard box. Field boxes frequently are used when fruit is to be packed in cartons. 1 Transferred to the Fruit Industries Research Foundation, Yakima, Wash. 2 Air circulation and other considerations involved in maintaining optimum storage conditions will be covered in other reports on apple storage. The more important factors affecting the utilization of storage space are size of unit load, aisle space, stacking height, kind of refrigeration and air circulation, and spacing and size of columns, posts, and girders. Total gross plant revenue for a given season usually has a direct relationship to the total number of boxes of apples stored. Therefore, possible savings that may be gained through shifts to lower unit-cost methods of handling cannot be considered as net savings if these methods reduce the total number of boxes that can be handled and stored and the consequent revenue received (assuming, of course, that the plant is not already operating at a loss). To illustrate this point, assume that a plant with a capacity of 100,000 boxes shifts to a lower unit-cost method of handling and reduces its storage capacity to 90, 000 boxes. By shifting to the lower unit-cost method it reduces handling costs from $5 to $2.50 per thousand boxes. The reduction in costs would amount to $275 per season. How- ever, if the loss of net storage revenue on the 10,000 boxes for this hypothetical plant amounted to 3 cents per box or $300 for the season, the plant would suffer a net loss of $25 by shifting to a lower unit-cost handling method. This report presents illustrations showing how various factors can be used to esti- mate the amount of space lost through use of different types and combination of types of materials-handling equipment under certain stated conditions found in older plants. In these illustrations, direct comparisons are not made between space lost or gained or the effect on the quality of the fruit. In some plants a change in the type of equipment might facilitate faster handling of the fruit during the harvest period. Faster handling might, in turn, aid in maintaining the quality of the fruit for a longer period. With respect to space gained or lost through changing the type of materials-handling equipment used and the consequent maintenance’ of fruit quality, each plant presents a separate problem. FACTORS AFFECTING STORAGE SPACE UTILIZATION In attaining maximum utilization of storage space, consideration should be given to: Providing optimum storage conditions for the fruit; maintaining the identity of grower lots; using time, labor, and equipment effectively; and moving the fruit into, within, and out of storage rapidly and gently. Otherwise, maximum space utilization could result in a net loss of revenue. The principal factors that affect the utilization of storage space in rooms of different designs or different dimensions are: (1) The size and spacing in storage of unit loads; (2) the number, width, and layout of aisles; (3) ceiling and stacking heights; (4) type and location of refrigeration and air circulation equipment; and (5) the size and spacing of posts or height of girders. In the Pacific Northwest, the more important types and combination of types of materials-handling equipment used for moving apples into storage rooms and stacking | them are: (1) Clamp-type 2-wheel hand trucks; (2) belt conveyors and clamp-type 2-wheel hand trucks; (3) floor chain conveyors and clamp-type 2-wheel hand trucks; (4) elevators and clamp-type 2-wheel hand trucks; (5) industrial forklift trucks and pallets; and (6) in- dustrial clamp-type lift trucks. The amount of cube or gross piling space that can be utilized in rooms of different dimensions varies considerably between these different equipment combinations because some of them require more operating space than others. Moreover, the heights to which boxes can be stacked efficiently differ, especially in confined areas. Unit Loads The size of unit loads handled by different types of equipment is an important factor in storage space utilization, particularly when unit loads are to be maintained throughout the stacking operation. Clamp-type 2-wheel hand trucks usually handle a unit load con- sisting of a single stack of 6 boxes of loose fruit or a 5- or 6-high stack of packed boxes | Z (fig. 1-A). For industrial truck handling, these 5- or 6-high stacks are grouped into 2, 4, 6, or 8 stacks, as shown in figure 1-B through 1-E, the exact number depending on the type and capacity of the equipment. If total plant volume justifies equipment owner- _ship costs, it is of course more efficient to handle larger unit loads, as more boxes are moved at one time and individual boxes are handled fewer times. However, inefficiencies may result from the handling of larger unit loads in some of the older plants which have relatively low ceilings and close column spacing. Table 1 shows the storage space occupied by unit loads handled by specified types of '_materials-handling equipment. More space between unit loads is required for some types of equipment than for others. For example, more space must be provided between loads for the outriggers of a straddle-type industrial truck than for a counterbalanced truck. When unit loads consisting of two or more individual stacks are handled by industrial trucks, the need for space between individual stacks is eliminated. Only enough space is ‘left between unit loads to permit adequate clearance for handling and air circulation. | Single stacks, for handling by clamp-type 2-wheel hand trucks, must be stored so that | space is provided on both sides of the boxes. Therefore the size of the unit loads and | space required between loads to insure safe, rapid, and smooth handling and storage | operations are important factors in space utilization. | Table 1.--Comparison of space occupied by boxes of unpacked apples in 6-box-high unit loads of specified sizes when stacked for handling with specified types of materials- handling equipment Space occupied by 1,000 stacked Dimensions of load plus Size of load other allowable spacet and type of equipment | Depth | Width | Height Space occupied by 1 unit load b oxes | 6 boxes--clamp-type 2-wheel hand Inches Inches Inches Cubic feet Cubic feet BeAaIC Mae ees ceca oldies bis oars erelewieicn| Le a /4 22 66 10.29 S752 | 12 boxes--industrial clamp-type PMC Verses c thiee sb evesees | Le 1/4 66 20¢12 1,676.66 24 boxes--industrial clamp-type bible sb TC Kost ere lat de. Mieraierdiele’s wie 'ed oii ti 2D 42.65 7 OS 36 boxes--industrial clamp-type RBar LISUCIGs sheiel a helsece dic ak estos MIST 1/2 63.98 Dee |36 boxes--industrial forklift mle CHMleTs Aeleveis SOs 6 este aie asia sb OT lL /e 66.25 1,840.28 '48 boxes--industrial forklift BISONS favcllo\cis o/e'e 6 0,6 tues ees Sele ars 49 1/2 87.46 1,821.99 + Allowable space for clamps, pallets, and air circulation. Aisle Space The principal factors that determine the number, width, and layout of aisles and the |consequent amount of storage space lost to aisles in apple storage rooms are: (1) Size of |lots which must be segregated by ownership, variety, and grade; (2) type of materials- |handling equipment used; (3) location of doors; (4) shape.or dimensions of rooms; \(5) overhead obstructions; and (6) State or local fire regulations. The aisles in a storage room serve to move fruit in and out of the room. They also t/facilitate segregation of the fruit by ownership, variety, and grade. The segregation and storage pattern may either simplify or complicate the aisle layout in individual rooms. For instance, if large blocks of fruit for only a few growers were stored in a room, the 3 Neg. N-18252 Neg. N-18249 Neg. N-18253 Figure 1.--Patterns of stacking used for different types of handling equipment. A.--Stacked for handling by two-wheel hand truck. B.--For 12-box industrial clamp truck. C.--For 24-box industrial clamp-lift truck. D.--For 36-box industrial clamp-lift truck. E.--For 36-box and: 48-box industrial forklift trucks. —_—— _ storage pattern would be relatively simple; only 1 or 2 aisles would be needed. However, | a greater number of aisles would be needed in a room of the same dimensions if it were | used to store a large number of small lots and if each grower's lot were stored so that it | would face or adjoin an aisle. This storage arrangement is necessary if boxes are to be | broken out of stacks with a minimum amount of handling. The need for ready access to each grower's lot is associated not only with the re- | quirements or needs of the growers but also to good storage practices. Good storage '_management includes constant observation of all lots to check on maturity and provides a basis for deciding when various lots should be packed and marketed. Therefore, in 'laying out aisles in a storage area, accessibility to individual lots is a consideration | which affects both handling costs and the amount of space required to store a given | quantity of fruit. | The following tabulation shows the width of aisles required for efficient operation of | specified types of materials-handling equipment: Equipment Aisle width Feet BeAr ay eR Wheel Ward BUTCH, .8% ie chels lole 0 0 eles (olla cicholicye: @ alels 61s wale ellelaysiiaye. ojo elleveverereds! ef 4 lao Lamp=type 2-wheel hand truck and belt CONVEYOL..ccecccccccccccccccccscccessce 4 pte Ors adnl IC OMVCVON cteiclelele c’elel «els wiclste « wleXs alcberolsle cis Yo eicils) 0) ©) Slelolafale-o =e) efeie'eilsiereie'ere« A, Papo indushim al eillamps truck agen: hanes. cistron’ s/c 4 elete leis ob e208 olare ole soe bie Wis ens ie ave 5 Set Sooner gy mdurci wvelleee Wermno } tisucike. Sede cael . bevste cat. te fenelaile Wavclietass aele creases aieioierSlale: ate evel e's Tie9 Seer roseimdus Getaicitemp ey truclssc. Stim led cate ce cide Ge seis + So bie aie overs wierd > Sieverord & oro = 10 SP comet pallet tandem or limembect mucileeye/cesetaely Shed. Wie earls ie Go Ureis she Baie wae aiel eid Waal lO | 48-box pallet and HOT astab SUG TEUR Cae re aes Bal cela cli choles ebatratiottewls Val ateianal crete beluate Sd see etetenets Pi 1D 1 Straddle-type truck requires only a 6 1/2-foot aisle. 2 Straddle-type truck requires only a 7-foot aisle. |The size of the materials-handling equipment and the overall dimensions of unit loads | handled are the key determinants of aisle width. Although straddle-type industrial trucks | can be operated in narrower aisles than those shown above, this type of truck requires a smooth floor, free of big cracks, holes, and other rough places, on which to operate. In a storage room 100 feet wide and 150 feet deep, in which 2-wheel clamp-type hand |trucks are used for handling fruit, two 4-foot aisles usually run the depth of the room. | Boxes of fruit are stacked at right angles to the aisles. If an industrial forklift truck is ‘used in this room, only 1 aisle, 9 to 12 feet wide, down the center (150 feet long) is needed. In a conventional plant which uses clamp-type 2-wheel hand trucks, the depth of the rows of boxes from the aisles usually does not exceed 30 feet. | A room 50 feet by 150 feet usually requires more aisle space than a room 75 feet ‘by 100 feet, even though they contain the same amount of floor space. In the wide, small- depth room, at least one aisle will have to run the full width of the room. If rows of stacked boxes become relatively long, a second aisle the width of the room may be needed |or one or more lateral aisles must be added. The type of refrigeration equipment used and its location sometimes dictate the aisle layout of storage rooms. Aisles should be laid out so that air circulation is parallel |to stack rows in forced-air circulation storages. In some systems, the aisle is used as a mixing plenum for the supply air; in other systems, the aisle serves as a return air duct. In either instance due regard must be given to the location of the aisle so that these \functions may be properly performed. Fruit cannot be stacked directly in front of duct openings because the constant flow of air, which usually is 1 or 2 degrees below freezing at the duct opening, may freeze the fruit. Thus, the aisle layout must permit the free circulation of cold air with no damage to the stored fruit. In storages equipped with pipe ‘coils certain clearances must be maintained between stacks and coils if freezing is to be javoided. 5 One factor, apart from the packinghouse operations, which affects the width of aisles, is the necessity for compliance with fire ordinances and regulations. In many areas these ordinances require a minimum aisle width of 4 feet. An aisle of this width will permit a clamp-type 2-wheel hand truck to be operated beside a belt conveyor; the conventional counter-weighted industrial trucks generally require aisles 9 feet or more wide. Stacking Height Stacking heights in the cold storage room are directly related to ceiling heights. Because of relatively low ceilings in many of the older plants, the stacking height is limited to 9 or 10 boxes. In more modern structures, common stacking heights range from 12 boxes to 24 boxes of fruit, or from 2 to 4 pallets high. Stacking height may be limited by the requirements for cold air circulation. As previously pointed out, it is necessary to stack those boxes adjacent to refrigeration coils and air ducts at lower levels to prevent the fruit from freezing. The handling method used also affects the stacking heights. The usual stacking heights for both packed boxes and boxes of loose apples when handled by specified types of materials-handling equipment are shown in table 2. From the viewpoint of storage space utilization, one of the most serious problems in older plants is that ceiling heights usually were not designed in terms of multiples of full unit loads. In a storage room in which the ceiling height permits a 9-box high stack, the 3 or 4 boxes above the original 6- or 5-high stacks will require individual handling of boxes to complete the stacks, or 2 sizes of unit loads must be made up. Refrigeration and Air Circulation Equipment In the older apple storage houses in the Pacific Northwest, coil-type refrigeration is commonplace. However, in recent years most installations are of the forced-air type, with the air distributed either from a central location or through ducts. The type of refrigeration equipment used affects utilization of cubic space with different types of materials-handling equipment. Table 2.--Optimimm stacking heights of apple boxes in cold storage rooms with use of dif- ferent types of materials-handling equipment Height of Optimum unit load stacking height Equipment Packed Loose Packed Loose fruit fruit Prue t fruit Boxes Boxes Clamp-type 2-wheel hand truck...ccccsees 5 tA 12-box industrial clamp-type truck..... 5 sai 24-box industrial clamp-type lift truck 5 Bh 36-box industrial clamp-type lift truck 5 eis 36-box forklift truck and pallets...... 5) 18 48-box forklift truck and pallets...... 5 18 1 Boxes stacked above the 5- or 6-high level are manually stacked. 2 It is general practice to place dunnage strips between each unit load to level and steady the second tier. Such material (wood strips) is 5/8 inch to 1 inch in thickmess. 3 The industrial clamp-type lift truck can break the height of the unit load to store at off heights of 9 or 15 boxes. The clamp-type truck, ordinarily is not used to stack 15 or 18 high. Coil Refrigeration Coil-type refrigeration is found in many older plants. Coils usually are hung from the ceiling or from the upper part of the walls. It is necessary for stored fruit to be | kept away from the coils to avoid freezing the fruit and to permit cleaning the coils. When industrial lift trucks are operated in rooms with coil-type refrigeration, adequate space must be available for moving the equipment through the room. Heavy metal guard | structures should be installed around the coils. Moreover, care must be exercised in | tiering the loads in order to minimize the loss of cubic space. In a coil-equipped room, constructed for handling clamp-type 2-wheel hand trucks, |a shift to forklift truck handling would require the addition of a pallet to each unit load, | which would often reduce by 1 box in each stack the amount of fruit that could be stored. Two pallets would add approximately 12 inches to the height of stacks. In other words, | the height of 11 boxes plus the height of 2 pallets is equivalent in height to boxes stacked 12-high without pallets. However, an industrial clamp-type lift truck, which requires no pallets, might be used without reducing stacking heights. The effect of refrigeration coils on space utilization usually can be minimized by installing them over the aisles. However, this may interfere with the handling of large |unit loads and still may require that the height of unit loads stacked near the coils be reduced. Central Fan Systems In a room with a central fan system, the layout of the aisles must conform toa \predetermined pattern. Usually this system of refrigeration consists of a cooling unit ‘and a system of ducts through which cold air is forced by fans. The cooling unit is not necessarily located in the storage room. The ducts may be as large as 8 by 8 feet initially and taper to about 2 by Zz feet at the terminal end. Their size, spacing, and location may reduce the stacking height in the areas beneath the ducts. Free Delivery Unit Systems By these systems cold air is delivered directly from the fan outlets into the storage room from one or more cooling units. Usually the equipment is located in the storage room. Occasionally a short run of duct is used between the fan and discharge opening _|so that the air may be discharged in the desired direction. In the older multistory plants these central air systems necessitated the use of slatted floors, which permit cold air to circulate from one floor to another. In these plants, as in those equipped _|with ducts, the aisles and stacks must be arranged so as to permit the proper circula- tion of cold air in order to maintain optimum storage conditions. Posts and Girders In multistory apple storage plants the upper floors and the roofs are supported by posts which usually are set on 16-foot centers (16 feet from the center of one post to the centers of neighboring posts or walls). Figure 2 shows the floor area of a bayina typical storage room. This spacing of posts may affect storage space utilization if a change is made from single-stack to multiple-stack unit loads. Maximum utilization of space between and back of the posts rarely is possible with the larger units. One means of avoiding the loss of space is to stack boxes adjacent to the posts by hand. However, this practice increases handling costs. Some types of equipment minimize this problem. The portable mechanical lift can be used to stack or break out single stacks of boxes 1 to 6 boxes high or a load of boxes 1, 2, or more layers high around a post or under a girder. Another possibility of reducing the amount of space lost around and behind posts when using an industrial lift truck is to turn the unit loads behind the posts at right it Ei on Oy DEPTH 16' SCALE IN FEET 5 ee et — lal 0 ! 2 3 a 5 i dao gatiooas GR memanaion |S’ —) TT