*« % V*o. 
 
 A Publication of The College of Agriculture 
 
 - \ \r u N 
 
 IVERSITY OF CALIFORNIA 
 
 COOLING AND HOLDING 
 EGGS ON THE RANCH 
 
 S. M. Henderson F. W. Lorenz 
 
 CALIFORNIA AGRICULTURAL 
 EXPERIMENT STATION 
 
 CIRCULAR 405 
 
k COLD ROOM 
 
 is essential if you want top prices for your eggs. 
 
 This circular tells you exactly how to construct and operate a ranch egg 
 storage room and precooling cabinet. 
 
 Perhaps you have a room you can convert to this purpose. If so, be 
 sure it meets all the requirements discussed in these pages. 
 
 Three things are important in maintaining top-quality eggs — time, 
 temperature, and humidity. Eggs should be gathered at least twice a day 
 and cooled as rapidly as possible to a temperature of about 55° F. and 
 80 to 85 per cent relative humidity. Cooling time is largely determined by 
 the rate of air flow past the eggs. We recommend a precooler and baskets 
 holding not more than 12 dozen eggs apiece. 
 
 Illustrations on pages 4 and 5 are used by courtesy of the Bendix Aviation Corporation, 
 Friez Instrument Division, Baltimore, Maryland. 
 
 September 1951 
 
 THE AUTHORS are S. M. Henderson, Assistant Agricultural Engineer in the Experiment 
 Station; and F. W. Lorenz, Associate Professor of Poultry Husbandry in the Experiment 
 Station. 
 
EGG QUALITY determines consumer acceptance 
 and relates directly to market value 
 
 Production of high-quality eggs is a 
 matter of increasing concern to the poul- 
 try industry. The consumer appeal of 
 good fresh eggs is so much greater than 
 that of inferior, stale, or deteriorated eggs 
 that egg quality in retail markets has a 
 considerable effect on total consumption. 
 This effect inevitably determines the price 
 the producer receives for his eggs. 
 
 Increasingly often the relation of qual- 
 ity to price is direct and immediate, as 
 when eggs are bought on grade or when 
 premiums are paid poultrymen who em- 
 ploy certain practices to insure superior 
 quality. Even in the absence of grade 
 buying or of specific premiums, however, 
 and in spite of local conditions such as 
 large imports from other areas, the price 
 of eggs will ultimately be determined by 
 the demand — and thus to a great extent 
 by the quality of the eggs produced. 
 
 The problem of producing and market- 
 ing high-quality eggs is a complex one 
 involving many variables. Among these 
 are the breeding of the laying flock, its 
 age, disease history, housing, nutrition, 
 the climate in which it is maintained, the 
 care the eggs receive on the ranch, and 
 ultimately the care, grading, and market- 
 ing practices to which they are subjected 
 at wholesale and retail levels. 
 
 This circular is intended to discuss only 
 one of these — the care of eggs on the 
 ranch. 
 
 Temperature and humidity 
 are responsible for egg quality 
 
 The factors most responsible for main- 
 tenance or loss of egg quality during the 
 period between laying and delivery are: 
 
 (1) time between laying and gathering, 
 
 (2) egg-room temperature, (3) speed of 
 cooling the eggs to that temperature, and 
 (4) egg-room humidity. Various types of 
 egg rooms and equipment are in use, or 
 have been suggested for maintaining sat- 
 
 isfactory egg-room conditions. The pur- 
 pose of this circular is to assist the rancher 
 in constructing and operating a ranch egg 
 cold room. 
 
 Temperature and humidity have im- 
 portant effects on the rates of flattening 
 of the yolk, weakening of the albumen, 
 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. 
 Yolk and albumen conditions are, of 
 course, important factors in consumer 
 acceptance of the product. 
 
 The temperature of the egg room has 
 a striking effect on all three of the above- 
 mentioned egg quality characteristics. Al- 
 bumen quality has been shown to decrease 
 more in 4 days at 80° F. than it does in 
 10 days at 65° F. The rate of yolk flatten- 
 ing is strikingly affected by temperature. 
 A day or two at approximately 100° F. 
 will produce flatter yolks than those re- 
 sulting from several months of cold stor- 
 age. 
 
 Evaporation of water from the egg is 
 also affected by both temperature and 
 relative humidity. Eggs stored at 87° F. 
 lose moisture 10 times as fast as when 
 stored at 31° F. at the same relative hu- 
 midity (82 per cent). At 56° F. and 48 
 per cent relative humidity, a group of 
 eggs lost 0.71 per cent weight during a 
 3-day storage period. Eggs stored for the 
 same period and temperature but at 64 
 per cent relative humidity lost only 0.43 
 per cent. 
 
 Low humidities will increase the rate 
 of moisture evaporation and thus increase 
 the size of the air cell. For example, in 
 an egg room in Ohio a striking loss in 
 average quality with increase in the num- 
 ber of Grade B eggs was observed at the 
 approach of winter. This egg room was 
 an underground basement with no special 
 
 [3] 
 
Relative humidity is the ratio of 
 vapor pressure produced by moisture in 
 the air to vapor pressure of moisture in 
 saturated air, that is, air holding all the 
 moisture possible. Relative humidity de- 
 creases as the temperature increases — 
 not, however, in direct proportion. 
 
 Dew point is the temperature at 
 which the moisture in the air will con- 
 dense out as liquid water; it is a meas- 
 ure of the quantity of water in the air. 
 Fog or condensation on the surface of 
 objects causing "sweating" results when 
 the temperature drops below the dew 
 point. 
 
 Relative humidity can be determined 
 by a sling psychrometer, which consists 
 of two thermometers, one bulb covered 
 with cloth — not shown in the illustra- 
 
 Determination of relative 
 humidity and dew point 
 
 tion. The cloth is saturated with water 
 and the psychrometer rotated with a 
 circular motion until the temperature of 
 both thermometers is constant. The as- 
 pirating psychrometer operates on the 
 same principle and is more convenient 
 and easier to read. 
 
 These temperatures are applied to the 
 psychrometric chart opposite in order to 
 find relative humidity and the dew point. 
 The relative humidity is determined from 
 the intersection of the vertical dry bulb 
 line with the wet bulb line. Note the 
 psychrometric chart example for an air 
 temperature of 91° and wet bulb of 
 72°. The dew point is read horizontally 
 to the left from the intersection point 
 and is 63.7°. In this case, water will con- 
 dense on any object 63.7° or colder. 
 
 Simple, direct-reading relative-hu- 
 midity indicators are available (see 
 illustration above). Although many of 
 them may be reliable, others are not 
 satisfactory for egg rooms. 
 
 cooling facilities, and the quality loss 
 occurred as a result of a seasonal de- 
 crease in humidity and in spite of the 
 seasonal decrease in temperature. It was 
 prevented by adding moisture as a fine 
 spray to the atmosphere of the room. 
 
 Since an egg may lose up to approxi- 
 mately 1 per cent of its weight after it is 
 laid without dropping from AA to A 
 grade, the loss during the ranch storage 
 period may not be significant. However, 
 this loss should be so minimized on the 
 ranch that the total loss during a longer 
 storage period will be as small as possible. 
 
 A temperature of 55-60° F. 
 is most practical 
 
 Optimum temperature for egg storage 
 is the lowest possible temperature above 
 the freezing point of albumen, or about 
 30° F., but this is not practical for ranch 
 egg-holding rooms for two reasons: 
 
 ( 1 ) The difference in the rate of deteri- 
 oration between 30° and approximately 
 55° is not great enough to be important 
 during the 3 or 4 days eggs are normally 
 held on the ranch (although it would be- 
 come increasingly more important during 
 longer storage periods) . 
 
 [4] 
 
- 
 
 
 The psychrometric chart is used with the aspirating or 
 sling psychrometer (above and left) for determining 
 relative humidity. 
 
 Wet bulb 75 
 
 temp. 72 
 
 30 35 40 45 50 55 60 65 70 75 80 85 90 
 Dry bulb or air temperature — F 
 
 120 
 
 (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 they 
 have chilled to below the dew point of 
 the atmosphere, they will condense mois- 
 ture or "sweat" when they are removed. 
 Sweating is undesirable because it pro- 
 motes bacterial growth and thus increases 
 the probability of spoilage, and because 
 moist eggs are easily soiled by the pack- 
 ing material or by being handled before 
 they have dried again. The dew point in 
 most parts of California in most seasons 
 
 rarely exceeds 55° F.; consequently a 
 temperature of 55° F. is usually the most 
 practical temperature for holding eggs on 
 the ranch. 
 
 In a few more humid areas eggs may 
 occasionally sweat when removed from 
 refrigerators held at that temperature. If 
 this occurs, a holding temperature of 60° 
 F. may be used with only slightly greater 
 loss in quality. Since 55° is the best tem- 
 perature for storing hatching eggs, a 
 room at this temperature can be used for 
 either commercial or hatching eggs or 
 both. 
 
 The humidity of the egg room should 
 
 [5 
 
have no influence on sweating so long as 
 conditions remain constant, since sweat- 
 ing occurs only when eggs are colder than 
 the dew point of the surrounding atmos- 
 phere, and the dew point is always below 
 atmospheric temperature except when the 
 relative humidity is 100 per cent. The 
 higher the humidity the closer will be the 
 dew point to atmospheric temperature. If 
 conditions in the egg room fluctuate and 
 the relative humidity is close to 100 per 
 cent, a temporary situation in which the 
 dew point is above egg temperature is 
 apt to occur and the eggs may sweat in 
 the egg room. 
 
 Mold: In cold storage operations hu- 
 midities greater than 80 to 85 per cent 
 increase the danger of mold, which need 
 not be considered here since eggs are 
 never held long enough in ranch egg 
 rooms to permit mold development. 
 
 High humidity lowers the 
 rate of moisture loss 
 
 Other conditions being equal, the rate 
 of moisture loss from eggs increases as 
 the relative humidity decreases. There- 
 fore, within the limitations discussed 
 above, the higher the humidity the better 
 are the holding conditions. 
 
 Time also plays a part 
 
 Cooling time is important, of course, 
 because eggs are laid at a temperature 
 
 of approximately 104° F., and the sooner 
 they reach the holding temperature the 
 lower will be the average temperature 
 during the holding period. Rapidly cooled 
 eggs have been shown to suffer less in- 
 crease in yolk shadow and less moisture 
 evaporation than slowly cooled eggs even 
 though the latter reach the holding tem- 
 perature within 24 hours, and even 
 though the subsequent conditions are the 
 same for both groups of eggs. 
 
 Cooling time (i.e., rate of attainment 
 of holding-room temperature) is deter- 
 mined by the rate of air flow (holding- 
 room air) past the individual eggs and 
 by the size and shape of the eggs. During 
 a test at 63 per cent relative humidity, 
 the least evaporation resulted from the 
 most rapid air movement and the most 
 rapid cooling rate. 
 
 Apparently the average egg tempera- 
 ture during the experimental cooling and 
 short holding period was more important 
 than the "local" humidity as affected by 
 air velocity. In this experiment the eggs 
 were subjected to air flow, and weight 
 loss was measured over a period of 3 
 days. Cooling time varied from 2.3 to 6.7 
 hours. 
 
 Cool eggs as rapidly as possible. Too 
 rapid a cooling rate has not been ob- 
 served, and the optimum rate may be the 
 maximum attainable with practical equip- 
 ment. 
 
 A MECHANICALLY REFRIGERATED COLD ROOM for 
 cooling and storing gives best results 
 
 Cooling and storage units such as base- 
 ments, dugout lockers, wet sacks over 
 cases, evaporative coolers attached to 
 rooms, or basket coolers have been sug- 
 gested and used in many localities. Al- 
 though the performance of units such as 
 these is satisfactory under some condi- 
 tions, variation in outside air temperature 
 and relative humidity alter the cooling 
 and storage conditions. Storage tempera- 
 ture, relative humidity, and egg cooling 
 
 rate are therefore not consistent, with the 
 result that the quality of the eggs de- 
 livered is, likewise, not consistent. 
 
 We recommend mechanically refriger- 
 ated cooling and storage units, since with 
 their use you can maintain constant stor- 
 age room conditions, thus minimizing the 
 decrease in egg quality during the storage 
 period. 
 
 Here follows a construction plan for a 
 storage room. 
 
 [6] 
 
Where shall you put it? 
 
 Locate the storage room (or cabinet) 
 close to the laying houses and next to the 
 grading room so that walking will be 
 minimized. 
 
 If possible, choose a location out of the 
 rays of the sun. 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 will reflect 
 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, thus using cer- 
 tain portions of floor, walls, and ceiling 
 already constructed. These must be insu- 
 lated in the manner discussed on pages 
 14 and 15. 
 
 Shall it be a cabinet 
 or a room? 
 
 The home-made cabinet type of egg 
 cooler can be constructed economically 
 for laying flocks of 2,000 birds or less. 
 For flocks larger than 2,000 birds, a room- 
 type cooler will probably cost less than a 
 cabinet. Many ranchers with small flocks, 
 up to 2,000 birds, may find a room more 
 economical to build, even if somewhat 
 larger than actually required, because of 
 simplified design. 
 
 In deciding on the type of cold storage 
 unit to use for the small flock, consider 
 availability of material, space, and labor 
 costs. 
 
 Use an egg precooler 
 
 A precooler will give the shortest cool- 
 ing time consistent with economical oper- 
 ation. Building a precooler may add 5 to 
 10 per cent to the expense of installation, 
 however. Hence many of the refrigerators 
 that have been installed since the first 
 University designs and recommendations 
 were published in 1946 do not include 
 this feature. 
 
 Here are the facts that should convince 
 you a precooler will pay for itself: Warm 
 
 The 3-in. holes in these shelves insure uniform 
 air flow through the pails. Do not cover unused 
 holes. 
 
 eggs packed in cases require over 30 
 hours to cool to refrigerator tempera- 
 tures, and warm eggs in ventilated baskets 
 set on the floor of the refrigerator (i.e., 
 with negligible air velocity through the 
 basket) require about 15 hours to cool 
 completely. A properly performing pre- 
 cooler will accomplish the same cooling 
 in 5 hours or less. The effects of these 
 
 [7] 
 
differences in cooling rate are significant 
 enough to be reflected in the average price 
 received for the eggs. 
 
 Temperature and humidity at which 
 eggs are held after they are cooled have 
 even greater effects than the cooling rate. 
 Poultrymen who install a refrigerator will 
 observe a striking improvement in quality 
 even though it has no precooler, and may 
 consequently be satisfied with its opera- 
 tion and unaware of the additional ad- 
 vantage that could be obtained with a 
 precooler. 
 
 The precooling shelves shown in the 
 sketch are designed to remove the animal 
 heat from the eggs and cool them to ap- 
 proximately room temperature in about 
 5 hours. The eggs from one gathering will 
 be nearly cool at the time of the next 
 gathering. Thus the refrigeration load 
 will be well distributed, permitting satis- 
 factory performance with a minimum- 
 sized refrigeration system. 
 
 You can use your precooler to store un- 
 graded eggs in addition to cooling them, 
 permitting the floor to be used only for 
 storage of cases. Do not overload the fan 
 by covering unused shelf holes, or the 
 motor may be damaged. 
 
 Determine the capacity of the precooler 
 by the size of your flock. The dimensions 
 of the precooler will be determined by the 
 size of egg buckets used and the number 
 of birds in the flock (table below). The 
 
 distance, A> between the shelves (see 
 drawing, page 7) must be such that there 
 will be approximately 3 in. between the 
 top of the pail and the bottom of the next 
 shelf (probably about 12 in. for most 
 installations). 
 
 The capacity of the precooler will be 
 determined by the size of the flock and 
 can be found from the table below. 
 
 The cooler should contain at least half 
 as many holes as the number of pails of 
 eggs cooled per day. For example, a flock 
 of 7,000 will produce 29 baskets per day. 
 Half of these — 15 baskets — will be cooled 
 at the same time. 
 
 If the baskets are 12 in. in diameter, 
 allow 14 in. of shelf length per basket. 
 Since the storage room for a flock of 
 7,000 is approximately 8 ft. wide inside 
 (page 13) ,7 pails can be cooled per shelf. 
 Three full shelves should be used to sim- 
 plify construction and provide extra ca- 
 pacity for times of better than average 
 production. 
 
 Allow a minimum of 20 cu. ft. of air 
 per min. for each pail or hole. Since each 
 shelf in the example contains 7 holes, a 
 fan capable of delivering at least 140 cu. 
 ft. of air per min. is required for each 
 shelf. An 8-in. exhaust fan will probably 
 be satisfactory for 6-, 7-, or 8-hole coolers. 
 A 6- or 7-in. fan will be suitable for 
 coolers with less than 6 holes. Do not in- 
 stall a fan if you do not know its capacity. 
 
 Normal Cold Storage Capacity for Flocks of Various Sizes 
 
 
 Storage Capacity 
 
 in Cases 
 
 
 Size of Flock 
 
 for Number of Deli 
 
 veries per 
 
 Number of Baskets 
 
 
 Week Indicated 
 
 Cooled per Day* 
 
 
 2 
 
 3 
 
 
 1,000 
 
 7 
 
 5 
 
 4 
 
 2,000 
 
 13 
 
 10 
 
 8 
 
 3,000 
 
 20 
 
 15 
 
 13 
 
 4,000 
 
 27 
 
 20 
 
 17 
 
 5,000 
 
 33 
 
 25 
 
 21 
 
 6,000 
 
 40 
 
 30 
 
 25 
 
 7,000 
 
 47 
 
 35 
 
 29 
 
 8,000 
 
 53 
 
 40 
 
 33 
 
 9,000 
 
 60 
 
 45 
 
 37 
 
 10,000 
 
 66 
 
 50 
 
 42 
 
 Baskets assumed to contain 12 dozen eggs each. 
 
 [8] 
 
You can attach a number of shelves to 
 a single fan by building a conducting 
 passage between them. This is not recom- 
 mended since construction is more diffi- 
 cult and connecting conduits may crowd 
 out a basket, thus reducing capacity. Two 
 or 3 small fans will cost little if any more 
 than a larger one of a capacity equal to 
 the total of the smaller fans. Shelves com- 
 plete with individual fans can be operated 
 independently. 
 
 You can precool cased eggs on the 
 shelves by using an A spacing of 15 or 
 16 in. and a hole spacing of 13 in. The 
 case bottom and flats must be well per- 
 forated to permit air flow around the 
 eggs. 
 
 Small baskets for eggs 
 are recommended 
 
 Large baskets for eggs are not recom- 
 mended since eggs in a large basket cool 
 at a slower rate than those in a smaller 
 one. Many producers prefer smaller bas- 
 kets because they are easier to handle and 
 breakage during carrying is less. 
 
 A galvanized pail with hardware cloth 
 bottom (illustrated) approximately 12 in. 
 across the top and 9 or 10 in. high, which 
 will hold about 12 dozen eggs, is recom- 
 mended for use with the precooler. A 
 pail of this type confines the cooling air 
 to the eggs better than a basket. Do not 
 place a pad irt the bottom of the pail; it 
 would restrict air flow through the eggs 
 and extend the precooling period. 
 
 How big shall you make 
 the storage room? 
 
 For the best quality eggs and best use 
 of the rancher's labor, eggs should be 
 delivered to the processor at least twice 
 a week and collected from the yard at least 
 twice a day. Collections 3 times a day 
 will produce a superior quality egg and 
 decrease the size of the required refriger- 
 ation system. 
 
 Assuming 60 per cent production, 
 which is the normal maximum for a flock, 
 minimum cold storage room capacities 
 
 Each pail has a hardware cloth bottom and 
 holds about 12 dozen eggs. 
 
 would have to be provided as listed in 
 the table on page 8. 
 
 Examples of storage units of various 
 capacity are shown on pages 12 and 13. 
 The minimum room for a flock, for either 
 2 or 3 deliveries per week, can be deter- 
 mined by referring to page 8. However, 
 if irregularities can be expected in weekly 
 delivery times or in time of grading and 
 if the flock might be larger than normal 
 at certain times, you should consider a 
 larger unit. 
 
 The clear inside height of rooms should 
 be nearly 8 ft. 
 
 A clear inside height of 6%, 7, or 7V 2 
 ft. would effect a saving of material and 
 would provide an adequate storage space 
 if the refrigeration evaporator could be 
 placed in a corner. However, some pre- 
 cooling space may be taken up by the 
 evaporator, there will be less empty case 
 precooling space, and the size of refrig- 
 eration equipment required will be re- 
 duced but little (see page 17) . 
 
 The precoolers for the larger plans 
 shown 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. 
 
 [9] 
 
f x 2" slats 
 
 2- l"x 2" supports 
 Insulation 
 
 2' -6" clear depth 
 
 Door hinged here 
 
 Storage and precooling cabinet for flock of 1,000 or less, with refrigeration at 1,800 Btu/hr. This 
 precooler (shown also on page 11 for a larger flock) is not as efficient as that on page 7, because 
 of simplified construction. Insulated panel doors (page 16) are recommended. 
 
 Those removed can be processed, or 
 can be stored on the floor for future treat- 
 ment. This is not a particular disadvan- 
 tage, since grading and casing twice a 
 day will probably be advisable with large 
 flocks in order to utilize labor effectively. 
 
 Use a square room for 
 greater economy 
 
 Adequate precooler capacity and en- 
 tirely sufficient storage room can be 
 
 provided for flocks of large size by using 
 a room with inside width of 7 ft., and 
 long enough to store the cases in the pat- 
 tern shown in the 7 ft. x 7 ft. or 8 ft. plan. 
 Moreover, a nearly square room is pre- 
 ferred to a rectangular room because, for 
 equal volumes, a square room requires 
 less material and less refrigeration. 
 
 The capacity of the rooms shown is 
 based on case stacks 4 high, which is a 
 satisfactory lift for the average individ- 
 
 [10] 
 
ual. The height of the room will permit 
 stacks 5 or 6 high, which will increase 
 the room capacity proportionally. This 
 is too high a lift for most workers and is 
 not recommended as general practice. 
 
 Work out an efficient 
 arrangement 
 
 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. This results if the door is at 
 a corner and the precooler is located on 
 an adjacent wall. 
 
 If you want to construct rooms of size 
 and shape other than those shown, the 
 refrigeration requirements may be deter- 
 mined as demonstrated by the following 
 schedule and example, based on the type 
 
 The cabinet below is for a flock of 1,000 to 2,000, with refrigeration at 2,800 Btu/hr. 
 Construction details are the same as on page 10. 
 
 "French" doors 
 hinged on 
 opposite sides 
 
 Insulation 
 
 [ii] 
 
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 ooo 
 
 Precooling shelves (3 high) are shown by circles, 
 as well as the location of the door and the rec- 
 ommended 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. 3,620 Btu/hr. 
 
 v 
 
 oooo 
 
 i±=S 
 
 ooooo 
 
 Flock of 3,600-4,100 
 
 6' x 7' inside, 28 cases, 15 baskets 
 
 Refrig. 5,300 Btu/hr. 
 
 Flock of 2,500-3,000 
 
 5' x 6' inside, 20 cases, 12 baskets 
 
 Refrig. 4,070 Btu/hr. 
 
 1/U 
 
 OOOOO 
 
 
 
 
 
 
 
 V 
 
 
 
 w 
 
 oooooo 
 
 Flock of 4,100-5,100 
 
 7' x 7' inside, 36 cases, 18 baskets 
 
 Refrig. 6,590 Btu/hr. 
 
 Flock of 3,000-3,600 
 
 6' x 6' inside, 24 cases, 15 baskets 
 
 Refrig. 4,740 Btu/hr. 
 
 [12] 
 
ooooooo 
 
 Flock of 5,100-6,000 
 
 7' x 8' inside 
 
 40 cases 
 
 21 baskets 
 
 Refrig. 7,430 Btu/hr. 
 
 Flock of 6,000-7,800 
 
 8' x 8' inside 
 
 52 cases 
 
 21 baskets 
 
 Refrig. 9,380 Btu/hr. 
 
 
 V 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 OOOOOOO 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 T v 
 
 
 
 
 
 OOOOOOO 
 
 Flock of 7,800-9,600 
 
 8' x 9' inside 
 
 64 cases 
 
 21 baskets 
 
 Refrig. 1 1,070 Btu/hr. 
 
 [13] 
 
of wall construction illustrated on page 
 15. Outside dimensions are used, and a 
 110° F. day is assumed. 
 
 Construction details 
 
 The egg cooling room will be operated 
 at a temperature between 50° and 60° 
 depending upon the dew point of the out- 
 side air (see page 4). Since operation 
 will be above the dew point, it is not 
 necessary to provide a vapor barrier in 
 the wall. Furthermore, since the tempera- 
 ture differences between the room and 
 the outside air will not be great, the in- 
 sulation requirements can be met simply. 
 
 Floor: The most satisfactory floor from 
 the standpoint of both cost and perform- 
 ance is 4 in. or more of concrete over 3 
 or more inches of gravel fill. However, 
 any concrete floor that has no air circula- 
 tion underneath would be satisfactory. 
 
 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 in. on center, with cross bracing and 
 other details conventional for frame con- 
 struction. The wall and ceiling are filled 
 with insulation such as redwood fiber, 
 mineral wool, expanded mica, or other 
 material with insulating properties com- 
 parable to these. 
 
 Do not leave any open space in the 
 wall. The material should be packed to a 
 density specified by the supplier. 
 
 Sawdust and planer shavings are in- 
 ferior to the materials listed above, since 
 they settle with time and may harbor in- 
 sects and rodents. Undesirable odors may 
 develop, particularly under high humid- 
 ity conditions. They may, however, serve 
 adequately as insulating material under 
 the following conditions: (1) structural 
 members should be 2 x 6 rather than 
 2x4; (2) provision should be made to 
 add additional insulation to the side walls 
 
 Calculations for a 
 
 
 suggested storage room 
 
 
 Floor area in sq. ft. x 3 = 
 
 Btu/hr. 
 
 Wall and ceiling area in sq. ft. x 4 = 
 
 Btu/hr. 
 
 No. baskets eggs cooled per day x 223 = 
 
 Btu hr. 
 
 Lights, cooler fan motor, and infiltration (Add 120 for room 
 
 
 of size up to approximately 25 sq. ft., 300 for room of 
 
 
 approximately 80 sq. ft., and an intermediate value for 
 
 
 an intermediate size.) 
 
 Btu/hr. 
 
 The total is the refrigeration needed in Btu per hr. 
 
 Btu/hr. 
 
 Suppose a producer with a flock of 4,500 has a room 6 ft. x 
 
 12 ft. x 8 ft. high, 
 
 which can be insulated for a storage room. These are the calculations: 
 
 The floor area. 72 ft. x 3 = 
 
 216 Btu/hr. 
 
 The wall area is 288 sq. ft., the ceiling 72. This sum, 360, x 4 = 
 
 1,440 Btu/hr. 
 
 A flock of 4,500 will produce 1 9 baskets of eggs per day to be 
 
 
 cooled (see page 8). 19 x 223 = 
 
 4,237 Btu/hr. 
 
 Heat load due to lights, etc., for a 72 sq. ft. floor area is 
 
 
 estimated between 25 sq. ft. and 80 sq. ft. to be 
 
 250 Btu hr. 
 
 The total of these 4 items, 6,143 Btu/hr., is the refrigeration 
 
 
 required and will determine the size of the unit cooler 
 
 
 and compressor. 
 
 
 [14] 
 
Double floor 
 
 Waterproof 
 building papei 
 
 Insulation board under joists 
 
 ^\\SS\\S\S\S\S\S^\\S\\\S^SSS^\SS\^\S^Sffs\\S\\SS\^S\\S.^7^ 
 
 T and G floor 
 
 £& 
 
 ^ 
 
 Waterproof 
 building paper 
 
 I 
 
 f 
 
 2-1" insulation 
 boards 
 
 Two ways to insulate a wood floor. The building 
 paper protects the insulation when the floor is 
 washed and keeps air from moving through 
 the cracks. 
 
 (and ceiling) if needed; and (3) insula- 
 tion odors which might affect egg quality 
 should not be permitted. 
 
 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 material and 
 will stand up under high relative humid- 
 ities. 
 
 Poured concrete and concrete block 
 walls with at least 1 in. of insulation 
 board on the inside wall are satisfactory. 
 The insulation board should be covered 
 with 1-in. lumber, plywood, or other ma- 
 terial to protect the insulation against 
 mechanical shock. 
 
 Doors and sills: Doors such as shown 
 in the drawings may be used. They must 
 
 Conventional frame construction such as that on 
 the right is recommended. 
 
 [15] 
 
Refrigeration 
 door gasket 
 
 2—1" insulation 
 boards nailed to door 
 
 Refrigeration 
 door latch 
 
 " plywood 
 
 —U — 
 
 
 1" horizontal board at 
 
 midpoint to support 
 
 insulation and brace door 4 stra P h,n 9 es 
 
 i I 
 
 Ax A" 
 
 \?" outside grade 
 plywood 
 
 2x4" 
 
 / 
 
 2 refrigeration door hinges 
 
 ^mmm?: 
 
 Vi" outside grade -^ 
 plywood 
 
 These doors can all be constructed on the ranch, although the bottom one is commercially avail- 
 able. The center and bottom doors should be put together with nails and water-resistant glue. 
 
 be wide enough to pass a man carrying a 
 case of eggs, or a cart used for transport- 
 ing cases and baskets of eggs. A width of 
 3 ft. will be adequate in most instances. 
 A raised door sill is not recommended if 
 you plan to use a cart. 
 
 A slight incline from the grading room 
 into the storage room will permit the use 
 of a cart, and the door seal at the bottom 
 will be adequate. If no incline is provided, 
 some clearance will be needed between 
 the floor and the bottom of the door. 
 Although this is not desirable, the leakage 
 will not be sufficient to impair perform- 
 ance seriously. 
 
 Dollies for stacking and moving cases 
 may be useful, especially in the larger 
 units, and whenever lift trucks are already 
 available. If you consider using dollies, 
 
 the door should be large enough to clear 
 them without difficulty. 
 
 Refrigeration system 
 
 The refrigeration system recommended 
 for ranch egg cooling, shown schemati- 
 cally, operates as follows: 
 
 Liquid refrigerant from the receiver 
 flows under high pressure (about 100 psi) 
 through the solenoid valve to the thermal 
 expansion valve, where the pressure drops 
 to 35 to 40 psi. The liquid refrigerant 
 evaporates to a vapor in the evaporator, 
 removing heat from the air passing 
 through the evaporator. The vapor is re- 
 moved from the evaporator by the com- 
 pressor, which also raises the pressure of 
 the vapor. The compressed vapor moves 
 
 [16] 
 
into the condenser, cools, and condenses 
 to liquid refrigerant, which runs into the 
 receiver. 
 
 This process continues until the air in 
 the room becomes cold enough to actuate 
 the room thermostat, which closes the 
 solenoid valve. This stops the flow of 
 liquid into the evaporator. The com- 
 pressor continues to operate ; the pressure 
 
 Thermal expansion valve 
 
 between the compressor and thermal ex- 
 pansion valve is lowered; and the pres- 
 sure switch shuts off the compressor 
 motor. When the air temperature in the 
 room rises a predetermined number of 
 degrees, the room thermostat opens the 
 solenoid valve; liquid refrigerant enters 
 the evaporator and partially evaporates. 
 This raises the pressure of the gas be- 
 
 EVAPORATOR 
 
 (a fan, not shown, 
 
 moves air around 
 
 the coils) 
 
 Room thermostat 
 
 (should not be located 
 
 in the air blast from 
 
 the evaporator) 
 
 t 
 
 Pressure switch 
 
 Drier (takes the 
 moisture out of 
 the refrigerant) 
 
 Schematic arrangement of the refrigeration system. 
 
 [17] 
 
tween the compressor and thermal ex- 
 pansion valve, and the pressure switch 
 starts the motor. 
 
 Other methods of control may be used 
 satisfactorily in many cases. Most instal- 
 lations can be operated with the pressure 
 switch as the temperature control, thus 
 saving the cost of the solenoid and room 
 thermostat. However, for accurate con- 
 trol and reliable long-time service, the 
 control system sketched is recommended. 
 
 Selection: Selection and installation 
 of the system by a competent refrigera- 
 tion contractor is recommended. 
 
 Complete "packaged" systems that can 
 be installed as a unit may be had in some 
 areas. 
 
 Specifications: Capacity or size of a 
 refrigeration system is specified in Btu 
 per hour, the heat-removal rate, for the 
 temperature of the evaporating refrig- 
 erant (the capacity decreases as the 
 evaporating refrigerant temperature is 
 lowered). Systems may also be rated in 
 tons. A ton of refrigeration is equivalent 
 to 12,000 Btu per hour and is used for 
 large systems. The refrigeration required 
 for various rooms is given with the 
 sketches on pp. 12-13, or may be calcu- 
 lated from the schedule on page 14. 
 
 The refrigerant should be Freon-12, 
 called F-12 in the trade. It is nontoxic, 
 
 noncorrosive, nonexplosive, odorless, and 
 colorless; it will not contaminate foods, 
 and it is chemically stable. 
 
 The evaporator or unit cooler must not 
 have less capacity than that specified 
 above. It must operate at a temperature 
 of no more than 10 to 15° below the room 
 air temperature. This difference deter- 
 mines the relative humidity of the air in 
 the room: the smaller the difference the 
 higher the humidity. Although there is 
 some variation between manufacturers in 
 this respect, it is probable that the 15° 
 difference will apply in most cases. The 
 fan on the evaporator should operate con- 
 tinuously to maintain a uniform tempera- 
 ture throughout the room. 
 
 The compressor unit, which includes 
 the compressor, condenser, receiver, and 
 pressure switch, must be balanced with 
 the evaporator as regards capacity. An 
 air-cooled condenser can be used in most 
 areas. If an outside temperature of 100° 
 or more can be expected for long periods, 
 you should consider a combination air- 
 water cooled condenser. Locate the com- 
 pressor unit where air circulation is good 
 and the heat from the condenser can be 
 dissipated to the outside air. 
 
 The room thermostat must have a range 
 of at least 50° to 60° and operate on a 2° 
 differential or less. 
 
 EFFICIENT COLD ROOM MANAGEMENT 
 demands close attention 
 
 Follow these directions 
 
 Always place warm eggs above cool or 
 cooling eggs on the precooling shelves. 
 Fill the bottom shelf first, then the second 
 from the bottom, and so on. If you use 
 this system, the heated air from the warm 
 eggs does not warm the cooled eggs. 
 
 Leave 3 in. space between the stored 
 cases and the room wall for air circula- 
 tion. Uniform case temperature is thus 
 insured. 
 
 Precool empty cases before filling them 
 with eggs. Put enough empty cases in the 
 
 cooler in the evening to handle the eggs 
 that will be graded the following day. 
 Empty cases may be stored in the cold 
 storage room if space is available. 
 
 Do not shut down the compressor dur- 
 ing cold periods. The evaporator fan 
 should operate when the outside air tem- 
 perature is below the set temperature for 
 the room in order to precool the eggs. 
 Furthermore, the refrigeration system 
 may be needed during the first part of 
 the precooling period even when the out- 
 
 [18] 
 
side temperature is below the storage rator fan are lubricated as specified by 
 
 room temperature. the manufacturer, the condenser is kept 
 
 clean, and air circulation around the corn- 
 Operation and maintenance pressor is not restricted. 
 
 A properly selected and installed sys- Oil seepage at any point in the system 
 tern will operate indefinitely without will indicate a leak that should be re- 
 servicing, provided the motor and evapo- paired by a serviceman. 
 
 In order that the information in our publications may be more intelligible it is sometimes neces- 
 sary to use trade names of products or equipment rather than complicated descriptive or chemical 
 identifications. In so doing it is unavoidable in some cases that similar products which are on the 
 market under other trade names may not be cited. No endorsement of named products is intended 
 nor is criticism implied of similar products which are not mentioned. 
 
 21, 600-9/51 (6443) AA 
 
test tube farming 
 pays off for you 
 
 the agricultural research done by the 
 iversity of California is field work. Much useful 
 knowledge comes to light through work done under 
 controlled laboratory conditions. 
 This information, after thorough checking and 
 application to field problems, becomes available to all 
 California farmers. Distribution of this knowledge 
 is made through: 
 
 LITERATURE: 
 
 Circulars, bulletins, lithoprints, and leaflets by specialists are 
 available free. These publications cover many subjects re- 
 lating to agriculture in the state. For a catalog of this litera- 
 ture write to the Office of Agricultural Publications, 22 
 Giannini Hall, University of California, Berkeley 4. 
 
 COUNTY FARM ADVISORS: 
 
 Farm Advisors are agricultural specialists with a background 
 of practical knowledge. They serve 52 counties throughout 
 the state and their mission is to help farmers work out their 
 problems. Get to know your Farm Advisor — take advantage 
 of his services. 
 
 MAIL INQUIRIES: 
 
 If you prefer to put your questions in a letter, mail them to 
 the Public Service Office of the College of Agriculture, Uni- 
 versity of California, either at Berkeley or at Davis. Your 
 problem will be referred to the person or department best ^ 
 able to give you the exact information you need. 
 
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 UNIVERSITY OF CALIFORNIA