7% 1 -A Division of Agricu ^^^^^ COOLING HOLDING EGGS on the RANCH (in S. M. HENDERSON F. W. LORENZ CALIFORNIA AGRICULTURAL EXPERIMENT STATION CIRCULAR 405 REVISED A COLD ROOM is essential if you want top prices for your eggs. To maintain top-quality eggs, three things are important — time, temperature, and humidity. Gather eggs at least twice a day, and cool them as rapidly as practical to a temperature of approximately 55° F while maintaining 80 to 85 per cent relative humidity. Cooling time largely depends on rate of air flow past the eggs. We recom- mend cooling in baskets holding not more than 12 dozen eggs each. This circular tells you how to construct and operate a me- chanically refrigerated cold room with precooling and storage facilities that are designed to give you best re- sults. If you have a room that you can convert to this purpose, be sure it meets the requirements discussed in these pages. The Authors S. M. Henderson is Associate Professor of Agricultural Engineering and Associate Agri- cultural Engineer in the Experiment Station, Davis. F. W. Lorenz is Professor of Poultry Husbandry and Poultry Physiologist in the Experiment Station, Davis. NOVEMBER, 1956 i The sketch below shows a mecha nically op- era ted cold room as recommended in this er- cular, with eggs precooled in baskets and stored in cases. M&j&ftS&tt This presents the over-all view. For details see the following pages [3 A cold room is essential for top egg quality and insures your getting top egg prices Producing and marketing high-quality eggs is a complex business. It involves the breeding of the laying flock, its age, disease history, housing, nutrition, cli- mate, the care the eggs receive on the ranch, and the care, grading, and market- ing practices to which eggs are subjected at wholesale and retail levels. This circular discusses only one of these problems — the care of eggs on the ranch. The aim: high egg quality Four factors are most responsible for maintenance or loss of egg quality dur- ing the period between laying and de- livery : Time between laying and gathering Egg-room temperature Speed of cooling the eggs to that temperature Egg-room humidity. Various types of egg rooms and equip- ment are in use or have been suggested for maintaining satisfactory egg-room conditions. We recommend a mechani- cally refrigerated cold room; this cir- cular is written to help you construct and operate one. Egg quality brings profits Refrigeration protects egg quality. The financial advantages it brings, however, also depends on many other things, such as Climate: in a cold climate refrigeration allows less room for improvement. Procedures by which climate has been modified: insulated, subterranean, or evaporative-cooled egg rooms. Marketing arrangements : how long eggs stay on the ranch. Initial egg quality: little financial gain is realized from dirty, misshapen, or undersized eggs. Report of field trial. The difference between mechanical refrigeration, as rec- ommended in this circular, and other cooling and storage methods used on 10 ranches, were studied in field trials in four areas of California. Higher income from refrigeration resulted in all cases (see table below). In this trial the egg production of the 10 ranches under study was divided in half; during five two-week periods spaced throughout the year, one half was refrigerated and the other was held under the conditions existing on the ranch prior to installation of the refrigerator. The two groups were graded separately. These differences were extrapolated to form the estimate of the annual extra in- come for refrigerated eggs recorded in the table. The extra price received for refrigerated eggs varied with the seasons and locations. During the cooler months the increase in price of refrigerated eggs was small but during the summer months it was considerable: 1$ per dozen in the North and East Bay areas, and up to 3^ in the San Joaquin Valley. Income differences found in the trial may be attributed, in part at least, to differences in size of flock, to average percentage of large eggs, and to quality of eggs laid. All eggs were sold on grade through a marketing organization that packs a grade AA in large size only. Thus the ranchers did not receive extra com- pensation for egg quality retained by refrigeration in jumbo, extra large, me- dium, and small eggs. A different grad- ing system would have increased these extra returns materially. Why low temperature and high humidity? Temperature and humidity have im- portant effects on the rates of flattening [4] Ranchers Using Mechanical Refrigeration Increased Their Income Substantially Results of a field test on 10 ranches Number of cases de- livered per week Non-refrigerated storages Average price in- crease per doz. Ig. eggs over the 10- week period in refrig. storage Income gain Ranch location Actual, during 10- week test Estimated, per year, based on the 10 test weeks East Bay 75 64 104 19 33 41 185 81 28 18 Barn 0.42c 0.37 0.53 0.59 0.19 0.66 0.41 1.09 1.22 0.69 $55 41 91 16 11 19 31 94 64 14 $288 North Bay Storage room Evaporative cooler . . . Egg room 213 475 86 Egg room 59 Sacramento Valley San Joaquin Valley . . . Evaporative cooler . . Hatching egg room . . Egg room 93 160 488 Evaporative cooler . . . Evaporative cooler . . . 331 71 of the yolk, weakening of the egg white, and evaporation of moisture from the egg. All of these in turn affect the grade of the egg — and thus its market value — through their effects on such grade char- acters as yolk shadow and air-cell size. Why high humidity? Economically, it is important to prevent the evapora- tion of moisture from eggs because It prevents loss of weight which would reduce many eggs from the "large" classification to "medium," or from "me- dium" to "small." It prevents loss in grade which may re- flect true deterioration in interior egg quality, or primarily the clues by which candlers do the grading. Why low temperature? High tem- perature speeds up deterioration of egg white and yolk: both flatten; the white liquifies or "thins," the yolk mem brane weakens, and the yolk often de velops a blotchy or "mottled" surface All these are true interior quality factors as evaluated by the consumers of eggs High temperature also affects egg grades even beyond measurably lower- ing egg quality : it affects the clues which the candler uses to estimate the amount of deterioration that has occurred, espe- cially the appearance of the yolk through the candled egg shell and the size of the air cell. The yolk becomes more promi- nent and the nature of its movement changes as the egg is turned in front of the candle. Short periods at high temperature may affect this candle clue even more than they affect actual deterioration. For in- stance, in one experiment eggs on which cooling was delayed for two hours after laying were compared with eggs (from the same birds) on which cooling was started at once. There was no difference in measured interior quality, but the eggs showed a significant difference in yolk- shadow visibility under the candle. Air-cell size is, perhaps, the most im- portant clue to the candler for estimating interior egg quality, even though it has no fixed relation to it. Air-cell size can be estimated objectively and, under or- dinary conditions, is closely related to the actual amount of deterioration. The size of the air cell is, of course, a direct (Continued on page 10) [5] High storage temperatures and long storage deteriorate egg quality FRESH 1 WEEK ff 2 WEEKS 13 WEEKS Broken out eggs show egg flattening and egg-white weakening under longer and warmer storage conditions. Loss of grade may result from high temperature, low relative humidity, length of storage, or a combination of all three This graph allows you to calculate weight loss (on which grading is based) from storage temperature, relative humidity, and length of storage. Following arrows in the example, you will find that eggs stored at 54° F and 65 per cent relative humidity will lose an average of 0.9 per cent of their weight in seven days which is not sufficient to increase the air-cell size out of the AA quality. If the relative humidity of the storage room is 50 per cent, the same eggs stored at 54° F will after seven days show a weight loss of 1.3 per cent resulting in air cells within the A quality range. You can find the weight loss for any temperature and relative humidity by moving through the graph as shown by the arrows of the example. For instance, storage at 85 degrees, and 50 per cent relative humidity for three days will produce at 1.55 per cent loss of weight and the resulting air cell will limit the grade to A. [6] Some instruments to measure relative humidity Sling psychrometer (left) will show air temperature on the uncovered thermom- eter, and wet-bulb temperature on the thermometer whose bulb is covered with drenched cloth. Sling psychrometer must rotate until temperature of both ther- mometers is constant. Wall-type thermometer (right) will pro- vide air and wet-bulb temperatures with- out having to rotate, but can be used only where there is air movement. Slide rule will show you the relative humidity from information obtained from either sling or wall-type psychrometer. Relative humidity is the ratio of vapor pressure produced by moisture in the air ro vapor pressure of moisture in saturated air— that is, in air holding all moisture pos- sible. Relative humidity decreases as tem- perature increases, but not in direct pro- portion. Dew point is the temperature at which the moisture in the air will condense out as liquid water; it measures the quantity of water in the air. When the temperature drops down below the dew point, eggs will start sweating when they are removed. [8] How to measure relative humidity and dew point First establish wet-bulb temperature and dry-bulb (or air) temperature with either a sling or a wall-type psychrometer. Then apply these temperatures to the psychrometric graph below, to find relative humidity and dew point. To find relative humidity: follow vertical dry-bulb line to intersection with wet-bulb line (slanted from upper left to lower right). Intersection of the two lines gives you relative humidity on curved line. To find dew point: after having established intersection for relative humidity, follow hori- zontal line to figures on the left of graph to find dew point. Example: Suppose air temperature is 91° F and wet-bulb temperature is 72° F. If you follow vertical air-temperature line at 91 and wet-bulb temperature line at 72, you will find they intersect at point A, indicating a relative humidity of 40 per cent on the curved line. Moving from point A horizontally to figures on the left, you will find dew point at 63.7° F. For better orientation the example is en- larged in the upper left corner of the graph. In the case illustrated in the example, water will condense on eggs when removed from storage 63.7° F or colder. Area of recommended operating conditions (55°-60° F and 80-85 per cent humidity) is indicated by shaded area. Wet bulb 75 temp. 72 Dew point 63.7 30 35 40 45 50 55 60 65 70 75 80 85 90 100 Dry bulb or air temperature — F 120 [9] measure of the amount of moisture evaporation that has accrued: evapora- tion requires time but is hastened by high temperatures and low relative hu- midities. Large air cells are evidence of age, high temperatures, or both — the two factors most responsible for deterio- ration of yolk and egg white — or low relative humidities. (How the egg con- tents react to age and heat is illustrated on page 6.) To be sure, under some conditions eggs will deteriorate considerably with little evaporation, but these conditions are not usually found in ranch operation. Also at least one condition — low hu- midity at low temperature — permits con- siderable evaporation with relatively little deterioration of the contents. Eggs of this sort are not readily distinguished from deteriorated eggs in ordinary can- dling procedures, and grade standards make no distinction. The normal relationships between stor- age temperature, relative humidity, and egg grades are shown in the graph on page 7. Keep temperature down to 55°-60° F Best temperature for egg storage is the lowest possible temperature above the freezing point of the egg white, or about 30° F. This temperature, however, is not practical for ranch egg-holding rooms for two reasons: 1. The difference in the rate of deterio- ration between 30° F and approximately 55° F is not great enough to be im- portant during the three or four days eggs are normally held on the ranch (al- though it would become increasingly more important during longer storage pe- riods). 2. Eggs must be removed from the ranch holding room and transported in a warmer environment to the receiving station. Prevent "sweating" of eggs. If eggs have chilled to below the dew point of the atmosphere, they will condense moisture or "sweat" when they are re- moved. Sweating promotes bacterial growth and thus increases the prob- ability of spoilage; also, moist eggs are easily soiled by the packing material or by being handled before they have dried again. The dew point in most parts of California rarely exceeds 55° F; there- fore a temperature of 55° F is usually the most practical temperature for hold- ing eggs on the ranch. In a few humid areas eggs may oc- casionally sweat when removed from re- frigerators held at 55° F. In that case, a holding temperature of 60° F may be used with only slightly greater loss in quality. Since 55° F is the best tempera- ture for storing hatching eggs, a room at this temperature may be used both for commercial and hatching eggs. The humidity of the egg room should have no influence on sweating so long as conditions remain constant. Sweating oc- curs only when eggs are colder than the dew point of the surrounding atmos- phere, and the dew point is always below atmospheric temperature as long as the relative humidity is less than 100 per cent. The higher the humidity the closer will be the dew point to atmospheric tem- perature. (See psychrometric chart on page 9.) Mold may develop in cold storage operations at humidities greater than 80 to 85 per cent; however, this is no prob- lem because eggs are never held long enough in ranch egg rooms to permit mold development. Keep humidity up to 80-85 per cent Hold the relative humidity of the ranch storage room as high as practical. For example, three or four days storage at 55° F and 45 to 55 per cent relative humidity does not cause enough evapo- ration to reduce to grade A most of the eggs what would otherwise have been AA's; but a few additional days in a [10] commercial storage or retail store would soon drop them to the A grade. There- fore, the higher the relative humidity on the ranch, the higher will be the grade at the retail level. Aim for relative hu- midity between 80 and 85 per cent but as low as 60 per cent may be appropriate for short-time storage — three or four days. See page 25 for ways to maintain high relative humidity in refrigerated storages. Eggs stored as recommended will lose quality much more slowly by egg-white deterioration than by increase in air-cell size from evaporation. Therefore, if you can hold down weight loss as much as possible by proper cooling and storage temperature and relative humidity, egg- white quality will not suffer significantly during the short period on the ranch. Cool eggs rapidly Newly laid eggs have a temperature of approximately 107° F. The sooner they reach the holding temperature the lower will be the average temperature during the holding period. Rapidly cooled eggs suffer less increase in yolk shadow and less moisture evaporation than slowly cooled eggs, even when the latter reach the holding temperature within 24 hours, and the subsequent conditions are the same for both groups of eggs. Cool eggs as rapidly as you can. No cooling rate has been observed that was too rapid. The best rate may be the fastest attainable with practical equip- ment. A practical construction plan for a mechanically refrigerated cold room Some ranchers use cooling and storage units such as basements, dugout lockers, wet sacks over cases, evaporative coolers attached to rooms, or basket coolers. Although the performance of such units is satisfactory under some conditions, variations in outside air temperature and relative humidity alter the cooling and storage conditions. Storage temperature, relative humidity, and egg cooling rate are therefore not consistent — and neither is the quality of the eggs delivered. We recommend mechanically refriger- ated cooling and storage units because they permit maintenance of constant storage-room conditions, thus minimiz- ing the decrease in egg quality during storage. Build at a convenient, shady place Locate your storage room (or cabinet) close to the laying houses and next to the grading room; it will save you walking. If possible, choose a location in the shade. Otherwise the walls and roof will absorb some of the solar heat, and the refrigerator will have to operate longer to keep the room cool. Aluminum or white paint on the outside wall will re- flect most of the sun's heat. You may reduce the initial cost and the solar-heat load by locating the cold room in an existing structure. If you use existing portions of floor, walls, and ceil- ing, be sure to insulate them in the man- ner discussed on pages 20 and 21. Cabinet or room? The home-made cabinet type of egg cooler can be constructed economically for laying flocks up to 2,000 birds. For larger flocks a room-type cooler will probably cost less than a cabinet. How- ever, many ranchers with flocks of less than 2,000 birds may find a room more economical to build — even if larger than required — because of simplified design. In deciding on the type of cold-storage [in unit to use for the small flock, much will depend on labor cost, availability of ma- terial and space. Install an egg precooler Warm eggs packed in cases require over 30 hours to cool from the animal temperature to refrigerator tempera- tures; body-warm eggs in ventilated baskets which are set on the floor of the Well-spaced precooling racks without fans are adequate for most ranches. refrigerator (that is, with little air flow through the basket) require about 15 hours to cool completely. A properly per- forming precooler will accomplish the same cooling in five hours or less. These differences in cooling rate may signifi- cantly influence the average price re- ceived for the eggs. Temperature and humidity at which eggs are held after cooling have even greater effects than the cooling rate. Poultrymen who install a refrigerator will observe a striking improvement in egg quality even without a precooler. Therefore they may be satisfied with their refrigerator, unaware of the addi- tional advantage they could have ob- tained with a precooler. Types of precoolers. Of the two main types of precoolers one uses the natural air movement in the refrigerator room (see drawing on this page) ; the other uses fans to move the air (see drawing on page 13) . A third possibility would be to have no specific precooler but to put the baskets of eggs on the floor of the re- frigerator room. In this case the moving air from the ceiling cooler will cool baskets of eggs on the floor in five to six hours. A stack of six uncased filler flats in the same location will cool in six to seven hours. If cased, the stack of filler flats will require 10 to 13 hours to cool. You can reduce cooling time about half by directing air from a household fan toward the container on the floor. Precooler using the natural air move- ment of the refrigerator (see drawing on this page), can have baskets on slatted shelves located close to the inlet to the ceiling evaporator. Eggs on slatted shelves will cool a little faster than on the floor. Stacks of filler flats will cool much more slowly because the room air moves perpendicular to the direction of air movement through the stack. Where low construction costs are necessary, these fan-less precooling racks are recom- mended over forced-air shelves. [12 The forced-air precooler (see drawing on this page) is recommended for large ranches where fast cooling is necessary to keep the eggs from accumulating. The slatted-shelf precooler is adequate if shelf space can be provided for all the eggs gathered at one time. The forced-air precooling shelves shown on this page are designed to re- move the animal heat from the eggs and cool them to approximate room tempera- ture in less than five hours. The eggs from one gathering will be nearly cool at the time of the next gathering. Thus the refrigeration load will be well distrib- uted, permitting satisfactory perform- ance with a minimum-sized refrigeration system. Know your fan capacity. Allow a minimum of 20 cubic feet of air per minute for each pail or hole. Since each shelf in the example contains seven holes, a fan capable of delivering at least 140 cubic feet of air per minute is required for each shelf. An eight-inch exhaust fan will probably be satisfactory for six-, seven- or eight-hole coolers. A six-inch or seven-inch fan will be suitable for coolers with less than six holes. Do not install a fan if you do not know its ca- pacity. Use one fan for one shelf. Do not at- tach a number of shelves to a single fan by building a conducting passage be- tween them. Such construction, while possible, is more difficult, and conduct- ing conduits may crowd out a basket, thus reducing capacity. Two or three small fans will cost little more than a large one of a capacity equal to the total of the smaller fans. Shelves complete with individual fans can be operated inde- pendently. Capacity of precooler. Determine precooler capacity by the size of your flock. The dimensions of the precooler will depend on the size of egg baskets you use and the number of birds in the flock (see table on page 14). Distance between shelves. Plan dis- tance between shelves so there is approxi- mately three inches between top of pail and bottom of next shelf (which in most installations amounts to a 12-inch shelf spacing). You can precool cased eggs on the shelves by using a shelf spacing of 15 or 16 inches, and a hole spacing of 13 Precooler using fans. Arrows indicate flow of air moved by the fans. The three-inch holes in the shelves insure uniform air flow through the containers. Do not cover unused holes. [13] inches. The case bottoms and flats must be well perforated to permit air flow around the eggs. Number of holes per shelf. The cooler should contain about 60 per cent as many holes as the number of pails of eggs cooled per day. For example, a flock of 7,000 will produce 29 baskets a day. About 18 baskets will be cooled at the same time. Number of shelves. If the baskets are 12 inches in diameter, allow 14 inches of shelf length per basket. Since the stor- age room for a flock of 7,000 is approxi- mately eight feet wide inside (see page 19), seven pails can be cooled per shelf. Three full shelves should be used to simplify construction and provide extra capacity for times of better-than-average production. The precoolers for the larger plans shown on page 19 will not hold all of the eggs laid per day if used for the maximum-sized flock. After cooling those gathered in the morning, you will have to remove a few baskets from the cooler to make room for those gathered later in the day. Those removed can be processed, or can be stored on the floor for future treatment. This is not a particular dis- advantage because grading and casing twice a day will probably be advisable with large flocks in order to utilize labor effectively. Precooler as storage. You can use your precooler to store ungraded eggs in addition to cooling them, permitting the floor to be used only for storage of cases. Do not overload the fan by covering un- used shelf holes, or the motor may be damaged. Gathering containers. Select con- tainers carefully so the eggs can be gathered easily, cooled quickly, and breakage during handling minimized. Baskets with rubber or plastic-covered wires are light weight, hold down break- age, and permit fast cooling. Filler flats — with or without carrying racks — can be used to gather the eggs and precool as shown in the photos on page 15. Filler-flat gathering reduces breakage and improves grade since eggs are gathered little-end down. Cool filler- flat stacks with the air stream approach- ing the side. Galvanized pails with hardware cloth bottom are excellent for the forced-air precooler but not appropriate for cool- How to Determine Storage Capacity Size of your flock Number of baskets (containing 12 dozen eggs each) that need to be precooled per day Storage capacity in number of cases you need if you have per week 2 deliveries 3 deliveries 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 4. 8 13. 17. 21 25 29. 33 37 42. 7 13 20 27 33 40 47 53 60 66 5 10 15 20 25 30 35 40 45 50 [14] Basket (left) and filler flats (right) are among containers that will enable you to gather eggs easily, also cool them quickly and minimize breakage. ing on the floor or on open shelves. Small baskets and pails are recom- mended over large ones because small containers are easy to carry, breakage is low, and they cool quickly. How Large a Storage Room? For best quality eggs and best use of the rancher's labor, eggs should be de- livered to the processor at least twice a week and collected from the yard at least twice a day. Collections three times a day will produce a superior quality egg and decrease the size of the required re- frigeration system. Assuming 60 per cent production — which is an approximate normal for a flock — you would have to provide at least the storage-room capacities listed on page 14 (see also examples of storage units of various capacity on pages 18 and 19). However, if you expect irregulari- ties in weekly delivery times or in time of grading, or if your flock might be larger than normal at certain times, you should consider a larger unit. Height The clear inside height should be nearly eight feet. of rooms A clear inside height of 6%, 7, or 7% feet would save material and still pro- vide an adequate storage space if the refrigeration evaporator could be placed in a corner. However, in this case some precooling space may be taken up by the evaporator; precooling space for empty cases is reduced; and the size of refriger- ation equipment required will be re- duced but little. Capacity Adequate precooler capacity and suffi- cient storage room can be provided for flocks of large size by using a room with inside width of 7', and long enough to store the cases in the pattern shown in the 7' x 7' or 8' plan on pages 18-19. A nearly square room is preferred to a rectangular room because, for equal vol- umes, a square room requires less ma- terial and less refrigeration. The capacity of the rooms shown is based on case stacks four high, which is a satisfactory lift for the average person. The height of the room will permit stacks five or six high, which will increase the room capacity proportionately. This is too high a lift for most workers and is not recommended as general practice. [15] Efficient arrangements Arrange your room in such a manner that: ( 1 ) The precooler is close to the door, and the walking path to it is as nearly a straight line as possible. (2) The unit cooler can be located as close to the ceiling as possible and the blast of cold air directed uniformly over the room. (3) The available space is used most efficiently. Place the door at a corner and the precooler on an adjacent wall. If you want to construct rooms of size and shape other than those shown, you can figure out your refrigeration require- ments by the calculations in the box on page 23, based on the type of wall con- struction illustrated on page 21. Outside l'x2" slats 2- l"x2" supports Insulation 2' -6" clear depth Door hinged here On these two pages you see samples of storage and precooling cabinets. Neither of them is as efficient as the one shown on page 13 but their construction is simple and they will be satisfactory for most ranches. Insulated panel doors, such as shown on page 22, are recommended. The cabinet above is designed for flocks of 1,000 hens or less. [16] "French" doors hinged on opposite sides Insulation This cabinet is for a flock of 1,000 to 2,000 hens, with refrigeration at 2,800 Btu/hr. Construction details are the same as for the cabinet on page 16. dimensions are used, and a 110° F day is assumed. Construction Details The egg cooling room will be operated at a temperature between 55° and 60° F depending upon the dew point of the out- side air (see page 9). Since operation will be above the dew point, it is not necessary to provide a vapor barrier in the wall. However, if the owner antici- pates operating the room at low temper- atures for long periods at a future time, a vapor barrier should be added. Your local contractor or building-material sup- plier can offer suggestions for installing. Furthermore, since the temperature dif- ferences between the room and the out- side air will not be great, the insulation requirements can be met simply. Floor: The most satisfactory floor from the standpoint of both cost and per- formance is four inches or more of con- crete over three or more inches of gravel fill. However, any concrete floor that has no air circulation underneath would be satisfactory. (Continued on page 20) [17] >v ooo Suggested layouts for cold rooms of various sizes Precooling shelves (3 high) are shown by cir- cles, as well as the location of the door and the recommended method of stacking cases (4 high)— shown by rectangles— for best use of space. Flock of 2,500 or less 5' x 5' inside, 16 cases, 9 baskets Refrig. 3,500 Btu/hr. \.f oooo \u y ooooo Flock of 3,600-4,100 6' x 7' inside, 28 cases, 15 baskets Refrig. 5,100 Btu/hr. Flock of 2,500-3,000 5' x 6' inside, 20 cases, 12 baskets Refrig. 4,000 Btu/hr. \t\ / ooooo } w oooooo FJock of 4,100-5,100 7' x 7' inside, 36 cases, 18 baskets Refrig. 6,000 Btu/hr. Flock of 3,000-3,600 6' x 6' inside, 24 cases, 15 baskets Refrig. 4,500 Btu/hr. [18 y / II ooooooo Flock of 5,100-6,000 7' x 8' inside 40 cases 21 baskets Refrig. 6,900 Btu/hr. Flock of 6,000-7,800 8' x 8' inside 52 cases 21 baskets Refrig. 8,200 Btu/hr. > } f ooooooo V v ooooooo Flock of 7,800-9,600 8' x 9' inside 64 cases 21 baskets Refrig. 9,900 Btu/hr. [19] A wood floor is not recommended for new construction, but an existing wood floor can be used by insulating as shown in the drawings. Air circulation under the floor should be restricted as much as possible during periods of hot weather. Wall and ceiling: These should be framed of 2 x 4 studs and joists spaced 16 inches on center, with cross bracing and other details conventional for frame construction. The wall and ceiling are filled with insulation such as redwood fiber, mineral wool, expanded mica, or other material with comparable insulat- ing properties. Do not leave any open space in the wall. Pack the material to a density speci- fied by the supplier. Sawdust and planer shavings are in- ferior to the materials listed above, because they settle with time and may harbor insects and rodents. Undesirable odors may develop, particularly under high humidity conditions. They may, however, serve adequately as insulating material if you (1) use structural mem- bers 2x6 rather than 2x4; (2) pro- vide for additional insulation to the side walls (and ceiling) if needed; and (3) avoid insulation odors which might affect egg quality. You can construct the outside wall of any conventional weatherproof material such as drop siding, rustic siding, ply- wood, sheet metal, stucco over rough sid- ing, etc. Inside walls and ceilings may be made of any material {plywood, T & G lumber, pressed wood, etc.) that will ade- quately retain the insulating materials and will stand up under high relative humidities. Poured concrete and concrete block walls with at least 1" of insulation board on the inside wall are satisfactory. Cover insulation board with 1" lumber, ply- wood, or other material to protect the insulation against mechanical shock. Doors and sills: Doors must be wide enough to pass a man carrying a case of eggs, or a cart used for transporting cases Floor construction Double floor "^V^ Waterproof building paper Insulation board under joists Ak^v\uvmu^^^^^^^uuu^^r\u^^um^^^ T and G floor £& -^ Waterproof building paper T 2-1" insulation boards Here are two ways to insulate a wood floor. Waterproof building paper protects the insulation when the floor is washed, and keeps air from moving through the cracks. [20] Walls and ceiling Provide under-roof ventilation 2 x 4" studs 16" OC Use this type of conventional frame construction with 2x4 studs and joists spaced 16" on center, with cross bracing and insulation. [21] Door and sill construction Panel door 2 strap hinges Refrigeration door gasket 2-1" insulation boards nailed to door Refrigeration door latch 2x4' Vi" plywood ^ 1" horizontal board at midpoint to support insulation and brace door ± "*-X