SF 501 C2& 33 in Cold Storage CvJ o AFTER READING Lir w H] IL: FC Before you 3 .,8oc COLD sro \-S SEND FOR AGBIC, DEPT. ' ' me machine, ilts. f DO UOIL /\IVIiVlWINi/\ PI 1 SOMETHING NEW EACH MONTH. THE FRED W. WOLF COMPANY 139-143 REES' STREET, Foot of Dayton CHICAGO, U*S, A. ADVERTISEMENTS P. &B. Insulating Paper ROR GOLD STORAGE. Absolutely air tight and moisture proof. No tar; entirely odorless and tasteless. The most dur- able and effective papers made for insulating- cold stor- age building's, cars, etc. P. & B. PAINT5 For coating- all wood or metal exposed to dampness, acids or alkalies. A positive preservative. THE STANDARD PAINT COMPANY Chicago Office, 189 Fifth Avenue 81-83 John Street, NEW YORK. CompoBoard -Air Tight T f t , Waterproof For Insulation... One thickness of COttlpO=DOcircl equal in efficiency to two courses of matched lumber with paper between. COMPO=BOARD is but a quarter of an inch in thickness while two courses of ceiling- are one and three-quarters inches. Space saved by using Compo-Board One and one-half inches .... This means that you can save enough space, which represents money value, by the use of Compo-Board in place of matched stuff, to pay the total 'cost of insulating-. For full information address NORTHWESTERN COMPO-BOARD CO. MINNEAPOLIS, MINN. A D VKRTISEM KNTS Rctsof wC | KOCK For Making Birne For Freezing Purposes IS SUPERIOR TO OTHERS BECAUSE IT IS A MINED SALT, AND ALMOST CHEMICALLY PURE. RETSOF SALT will make a pure, clear brine, and keeps scale or corrosion of pipes or tanks down to a minimum. RETSOF SALT will go further than any other when used with ice to form a FREEZING MIXTURE. RETSOF SALT is used and endorsed by leading ice manufacturers and cold storage warehouses. THE BEST IS ALWAYS THE CHEAPEST. Joy Morton & Co,, Agents I. C. Pier No. I, CHICAGO Manilla Clean INSULATING FABRIC Durable NO WOOD PULP WIDEST PAPER IN THE WORLD. IMPROVING INSULATION. REDUCING NUMBER OF LAPS. ODORLESS^! FAY MANILLA ROOFING COMPANY 1 1 06 R. E. TRUST BUILDING FA CAMDEN, N. j. PHILADELPHIA EGGS IN COLD STORAGE THEORY AND PRACTICE IN PRESERVING EGGS BY RE- FRIGERATION. DATA, EXPERIMENTS, HINTS ON , CONSTRUCTION, ETC., FROM PRACTICAL EXPERIENCE, WITH ILLUSTRATIONS. BY MADISON COOPER. CHICAGO : H. S. RICH & CO. 1899. Copyrighted 1898, IX 1 )') BY MADISON COOPER. PKKSS OK ICK AND RKFRIOIOK \ riox. CHICAGO. PREFACE. IN the interest of a better understanding 1 and dissem- ination of knowledge on the cold storage of eggs, the writer has communicated with quite a large num- ber of individuals and companies, asking their ideas and requesting that they give full answers to a printed list of questions sent them. Although, at first, the replies were rather slow in coming in, the total result of these letters has been most gratifying; nearly one- half acknowledging receipt of the inquiry, and more than one-half of this number giving fairly full replies to the questions submitted. Considering the fact that the inquiries were regarded by some as being of a rather personal nature, the proportion of managers sending full replies is large. Several gentlemen were frank enough to say that personal considerations pre- vented them from giving any information; others gave guarded or partial replies. In the main, how- ever, storage men have been willing to give informa- tion and exchange ideas. The list of inquiries sent out covers the subject very thoroughly, and divides it into six different parts, with three separate questions relating to each. To the data so cheerfully furnished by others is added information from thewriter's experience and practice, with such explanation of theory and practice as may seem necessary to a clear understanding of the prin- ciples of successful egg refrigeration. It is hoped that those who are new to the business may obtain valuable information from these collected data, and that those with experience may derive some benefit in the way of a review, and possibly pick up some new ideas as well. A large portion of the matter contained in these Q C U fi x - 4 PREFACE. pages appeared in Ice and Refrigeration as a series of articles entitled: "Eggs in Cold Storage." The present book is printed for the purpose of putting the matter in permanent form, believing that those who have followed the original articles would find it convenient for future reference. While the present book has many shortcomings, and there is no doubt room for the addition of much information, reliable data, and the results of extended observations and tests, there has not heretofore been anything like a complete write-up of the subject; and in consideration of this fact the reader is asked to be liberal in his criticism. If any errors or lack of details are noted, the author would gladly acknowledge and explain the points at fault if his attention is called toany. No other object has been in mind in writing these articles than a furtherance of scientific knowledge on the subject of refrigeration as applied to the preservation of per- ishable products, and the great assistance rendered by those who have written painstaking replies to the list of inquiries is hereby acknowledged. The com- bination and comparison of information are beneficial, and if those who have further data or records of tests will only put them before others in their line of busi- ness, no loss will be sustained by the individual giv- ing the information, while much general good will result. INTRODUCTION. THE value of the eggs placed in cold storage for preservation is estimated at about $20,000,000 annually for the United States alone. Considering the importance the industry has already attained, its rapid growth and future outlook, the amount of ac- curate information available to those engaged in the business seems very meager. The difficulties to be overcome, the skill required. and the importance of a well designed structure are not usually explained by those interested in promoting new enterprises in this line, and consequently not appreciated by those mak- ing the investment. Financial disaster has over- taken many large companies who have erected costly refrigeratingwarehouses; thosewhich have succeeded have been forced to install new systems, make expens- ive changes, and make a thorough study of the prod- ucts handled. The experience of nearly all has been emphasized at times by heavy losses paid in claims made by customers for damage to goods while in storage, or the necessity of running a large house while doing a very small business. Those about to become interested in the business may find food for thought in the above, and the history of a dozen houses, in diiferent localities, will be good information for would-be investors. The scarcity of knowledge on the subject in hand, while being partly the result of the half developed state of the art until very recently, is also very largely owing to narrow-mindedness on the part of some of the older members of the craft, who have largely obtained their skill by years of experience and study, some of them having expended large sums on experimental work. The same experiments have 6 INTRODUCTION. perhaps been made before, and are of necessity to be made again by others, simply because the first experimenter would not give other people the benefit of his experience. It seems at this stage in the de- velopment of refrigeration, that the improvements to be made during- the next twenty years will be of very much less importance than those made during- the twenty years just ending-; trade secrets, so jeal- ously guarded by some, must disappear, as they have in other branches of engineering-. Storag-e men have been oblig-ed to work out their own salvation in stor- ing- problems, sometimes sending their most difficult points to be answered through the columns of Ice and Refrigeration, and, perhaps, comparing ideas with those of their personal friends in the same line of business. It is to be observed that the most pro- gressive and up-to-date manufacturing concerns in the United States to-day are giving their contempo- raries every opportunity of observing their methods, and are very willing and anxious to talk over matters pertaining to their work, from an unselfish stand- point. So, too, the successful cold storage of the future will be sure to make " visitors welcome." In anything which will appear in these articles, it is not the writer's intention to convey the idea that any mere theoretical knowledge, which can be ac- quired by reading and study, or even by an exchange of ideas in conversation, can take the place of practi- cal observation in actual house management; but there are applications of well known natural laws, which are not generally understood by storage men, and their progress is handicapped from lack of this theoretical knowledge. The two following illustra- tions, bearing on temperature and ventilation, are among the common errors made in practice, yet easily understood when studied and tested: Some storage houses have formerly held their egg rooms at 33 F., fearing any nearer approach to the freezing point of INTRODUCTION. 7 water (32 F.), thinking- the eggs would freeze. A simple experiment would settle this point, giving the exact freezing- temperature, as well as the effect of any low temperature on the egg tissues. Again, others have thought to ventilate by opening- doors during- warm weather. It never happens that storag-e rooms can be benefited by this treatment at any time during- the summer months, and only occasionally during* spring- and fall. The dew point of outside air is rarely below 45 F. during- summer, and when cooled to the temperature of an eg-g- room, moisture will be deposited on the goods in storage, causing- a vigorous -growth of mildew. EGGS IN COLD STORAGE. CHAPTER I. TEMPERATURE. TEMPERATURE is selected for first considera- Temperature . . . ., ,, ,. . . more important tion, as it is the primary elementoi reingeration, than any other Jf -,.,. ^ A condition. and more important than any other condition. Correct temperature alone, however, will not produce success- ful results, anymore than a g-ood air circulation, or cor- rect ventilation, would give good results with a wrong- temperature. This applies more especially to egg re- frigeration, someproducts requiringonlyalowtemper- ature for preservation. The common impression of cold storage is what the name implies simply a build- ing in which the rooms may be cooled to a low degree as compared with the outside air. Even those who build, sell and erect refrigerating machinery and appa- ratus often show either gross carelessness or ignor- ance of the requirements of a house which will produce successful results. After a careful examination of some of the recently constructed houses, supposed to be strictly modern and up to date, the writer gets the impression that the architects regard temperature as the only requisite for perfect work. Some of the unskiiifuiiy rooms in these new houses are simply insulated and e^j? m?ms. fitted with brine or ammonia pipes, the location of the coils having no attention whatever, being placed, in most cases, in convenient proximity to the pipe main, and in one or two instances, the top pipe of the cooling- coils was fully two feet from the ceiling. The ne- cessity of providing for air circulation seemed not worthy of consideration, to say nothing of the lack of anything like an efficient ventilating system. Questions regarding the correct temperature of Opinions egg rooms have been asked repeatedly of storage correct'"* , - j.i ' i i temperature. men who have been in the business long enough to be 10 EGGS IN COLD STORAGE. looked to for advice, the same person, perhaps, giving- a different answer, from time to time, as his ideas changed. The query has also been asked and answered through the columns of ICE AND REFRIG- ERATION a number of times. At present, however, there is no temperature on which a large majority of persons can agree as being- rig-ht, and as giving- su- perior results to any other. The claims made by the advocates of different temperatures will be consid- ered, to determine, if possible, what degree is giving the best results in actual practice. The three questions relating to temperature were temperature. wr itten to draw out opinion as to the right tempera- ture, the lowest safe temperature, and what delete- rious effect, if any, the egg sustained at low tempera- tures, which did not actually congeal the egg meat. The three temperature queries were: First. At what temperature do you hold your rooms for long period egg storage? Second- What temperature do you regard as the lowest limit at which eggs may be safely stored? Third. What effect have you noticed on eggs held at a lower temperature? Fig-ures All the replies received contained answers relative received relat- to temperature, and by a very small majority 32 F. is the favorite temperature for long period egg storage. Some few, 33 F. and 34 F., with a few scattering ones up to 40 F.. Under the freezing point, none recommended a temperature lower than 28 F., and for a very obvious reason, this being near to the actual freezing temperature of the albumen of a fresh egg. A very respectable minority say a tem- perature ranging from 30 F. to 31 F. is giving them prime results; and several recommend 30 F. straight, and say they should go no lower. In recent years there has been a decided tendency among storage men to get the temperature down near the safety limit, but many houses are so poorly equipped that EGGS IN COLD STORAGE. 11 they are unable to maintain a uniform low tempera- ture below 33 F., without danger of. freezing- eggs where they are exposed to the flow of cold air from coils. A house must be nicely equipped to maintain low temperatures with safety. More houses would use temperatures under 32 F., were they able to, without danger to the eg-g-s. A very successful east- ern house issued a pamphlet in 1892. At that time they maintained a temperature of 32 F. to 34 F. in their rooms. In sending- out this little book during the winter of 1897-98 a postscript was added, as fol- lows: " This pamphlet was published in 1892, when our plant was started. Since that time all first- class cold storag-e houses have lowered their temper- atures materially." No better illustration than this can be cited to show the tendency of the times. These people now use a temperature of 30 F. for eg-g-s. Most of the replies received contained answers to Re P liesto query No. 2. question No. 2, and the greater portion state this as being- about 2 F. lower than that recommended for long- period storag-e. It is presumed that these two degrees are allowed as leeway, or margin of safety, for temperature fluctuations. Some state that eg-g-s cannot be safely held below 32 F., but give no reason why, while two or three say a temperature of 27 F. will do no harm to eg-g-s in cases. One reply states that egg's held in cut straw at 25 F. for three months showed no bad symptoms. It has never been made clear how the package can be any protection against temperature, when the temperature has been contin- uously maintained for a length of time sufficient to allow the heat to escape; and we know that eggs will positively freeze at 25 F., as proven by experiments mentioned in another paragraph. The answers to question No. 3 were few in num- Replies to . ., __... . , 1 query No. 3. ber, but cover a wide range. The scarcity of data on this point indicates that few have experimented with 12 EGGS IN COLD STORAGE. eggs at temperatures ranging- from 25 F. to 30 F. Some say: "Dark spot, denoting germ killed"; others, "white gets thin"; others, "eggs will decay more quickly"; or, "they wnl not 'stand up' as long when removed from storage." It is also claimed that "yolk is hardened or 'cooked' when temperature goes below 32 F." Some answers state a liability of freezing if eggs are held in storage at a temperature below 32 C F, for any length of time. As far as possible, we will dig out reasons for the tempatureB W c ^ a i ms made by advocates of both high and low tem- peratures, both having equal consideration. Taking 29 F. or 30 F. and 38 F. or 40 F., as representing the lowest and highest of general practice, we will see what is claimed by each ; and also the faults of the other fellow's way of doing it, as they see it. Those who are holding their egg rooms at 40 F. say it is economical, that the eggs keep well, that the consis- tency of the egg meat is more nearly like that of a fresh egg after being in storage six months, than if held at a lower temperature. As against a low tem- perature they say: A temperature of 30 F. is expen- sive to maintain; the yolk of the egg becomes hard and the white thin, after being in store for a long hold; and that when the eggs are taken from storage in warm weather it will require a longer time to get through the sweat than if held in storage at a some- what higher temperature, resulting in more harm to the eggs. Some claim that the keeping qualities are impaired by holding at a temperature as low as 30 C F.,. and others note a dark spot, or clot, which forms in the vicinity of the germ, when eggs are held below 33 F. Against this formidable array of claims, the low temperature men have some equally strong ones, although fewer in number. They say: There is very much less mildew, or must, at 30 F. than at temperatures above 32 F.; the amount of shrinkage or evaporation from the egg is less; an egg can be EGGS IN COLD STORAGK. 13 held sweet and reasonably full at this temperature from six to eight months. This last claim is a broad one, and very few houses are turning- out eggs an- swering to this description. The following, relating to high temperatures, is quoted from a letter written by one of the best posted Je men in the business, who has spent much money and time on experiments, and studied the question for years. He says: "A temperature of 40 F. is very good for three months' holding, but if they run over that, it is more than likely the eggs will commence to cover with a white film, which grows the longer they stand, and finally makes a musty egg." This gen- tleman advocates a temperature of 30 F. for long period holding. It should be noted that the high temperature men ignore entirely the effect of high temperatures on the growth of this fungus, spoken of above as a white film. The worst hing about most storage eggs is the taste caused by this growth, (usually called mildew or mold), which results in what is commonly called a musty egg. To enable us to understand the validity of these claims made by the 30 F. people, it will be necessary for us to ascertain the conditions which are favorable, and also the con- ditions which are unfavorable for the propagation of this growth of fungus, which has given storage men so much trouble, ever since cold storage was first used for the preservation of eggs. Heat and moisture are the two conditions lead ing- Causes operat- & ing- to produce to its rank growth, and the opposite dry ness and cold [J I 8rrow1 JJ 1 of s will retard or stop the growth entirely. In moist, in oM storage, tropical countries many species of this parasite grow, while in the cold, dry regions of the north its exist- ence is limited to a single variety. The causes lead- ing to a growth of the fungus on the outside of an egg are not far to seek. It feeds on the moisture and products of decomposition which are being constantly given off by an egg, from the time it is first dropped 14 EGGS' IN COLD STORAGE. until its disintegration, unless immersed in a liquid, or otherwise sealed from contact with the air. This evaporation not only takes moisture from the egg, but carries with it the putrid elements from the egg tissue, resulting- from a partial decomposition of the outer surface of the eg-g- meat. Conditions of excess- ive moisture and the presence of decaying- animal or vegetable matter, tog-ether with a moderate degree of heat, are essential to the formation of fungus of the species which are found growing- on eg-g-s in cold storage. As the heat and moisture are increased, the growth of fungus will be proportionate. Furthermore, we all understand that heat hastens decomposition, and the partial decomposition of an egg results in a growth of the fungus, as before explained, when con- ditions of temperature and humidity are favorable. If the temperature is low, this growth is slow; for in- stance, if eggs are held at a temperature of 30 F. in an atmosphere of given humidity, the growth of fungus is less rapid than if held at any temperature higher, with the same per cent of humidity. As our subject merges into humidity here, the reader is referred to what is said under this head in another chapter, someexperi- Returning to the objections urged against low > Difference between the dry and wet thermometers (tf). Table of rela- v tive humidity. K.-*- 1 Q 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.S 6.0 Q 28 94 88 82 77' 71 65 60 54 49 43 38 33 28 7.9 94 89 83 77, 72 66 61 56 50 45 40 35 29 30 94 89 84 78 73 67 62 57 52 47 41 36 30 31 95 89 84 79 74 68 63 58 53 48 43 38 31 32 95 90 84 79 74 69 64 59l 54 50 45 40 32 33 95 90 85 80, 75 70 65 60 56 51 47 42 33 34 95 91 86 8ll 75 72 67 62 57 53 48 44 34 35 95 91 86 82 76 73 69 65 59 54 50 45 35 36 96 91 86 82 77 73 70 66 61 56 51 47 36 37 96 91 87 82 78 74 70 66 62 57 52 48 37 38 96 92 87 83 79 75 71 67 63 58 54 50 38 39 96 92 88 83 79 75 72 68 63 59 55 52 39 40 i 96 92 88 84 80 76 72 68 64 60 56 53 40 The above short table needs no explanation fur- ther than has been already given. It will cover any case in egg room observations. This table was not intended for cold storag-e work, being- a part of the regular humidity tables published by the Weather Bureau. The full set of tables can be had by table 28 EGGS IN COLD STORAGE. addressing- the chief of the Weather Bureau, Depart- ment of Agriculture, Washington, D. C. They are published in pamphlet form, along 1 with tables giving- dew point temperatures. Observers must work out the small fractions for themselves, if they think necessary, but results within the limits covered by the table are near enough for present practical pur- poses. It is of no use to test for moisture unless having* the ability to control it, any more than a thermometer would be of use unless the means of regulating* tem- perature were at hand. Humidity can be controlled by ventilation and the use of absorbents, which are considered elsewhere. V'J A CHAPTER III. CIRCULATION. vigorous and penetrating* circulation of air must circulation * . . essential. be maintained in a cold storage room for eggs if good results are to be insured. The importance of this condition, as applied to eggs especially, is quite generally appreciated, and it is noticeable that the warehouses producing the most perfect work have scientific and carefully designed air circulating sys- tems. It is also a fact that a strong, searching circu- lation will do much to counteract defects in a cooling apparatus, or wrong conditions in the egg room in some other particular. In proof of this, the writer is familiar with a number of successful houses where prominence is made of the air circulating system only, some of the other conditions being neglected al- together, or attended to in a perfunctory manner. Before going farther, it is best that we separate circulation n * . ventilation. circulation from its tangle with ventilation. These two terms are quite commonly confused when applied to cold storage work. Circulation, as here discussed, applies to the motion of air within the storage room air currents resulting from a difference in tempera- ture of the air in different parts of the room, or the result of mechanical force applied to the air by use of fans, blowers or exhausters. In distinction from cir- culation, ventilation means the renewal of the air of a storage room, either by forcing fresh air from the outside atmosphere into the storage room, or by ex- hausting the foul air from the room. Ventilation is not under consideration here, but will be taken up as a separate subject. The reason why a vigorous and well distributed circulation ~ ^ and moisture circulation of air in an egg room will give superior absorbing results over a sluggish or partial circulation may not be readily apparent. A circulation of air is of benefit in combination with moisture absorbing capacity in 29 30 EGGS IN COLD STORAGE. the form of frozen surfaces or deliquescent chemicals. Stirring- up the air merely, as with an electric motor fan, without provision for extracting- the moisture, is of doubtful utility, and may, in some instances, prove positively detrimental, as it is liable to cause conden- sation of moisture on the goods, or walls of storag-e room, instead of its correct resting- place: the cooling- coils and absorbents. Let us see how the circulation of air in a storag-e room operates to benefit its condition. Under head of temperature, we have seen that circulation. fo Q evaporation from an eg-g- contains the putrid ele- ments resulting- from a partial decomposition of the eg-g- tissues, and that the air of a storag-e room carries them in suspension. It is probable that these foul elements are partly in the form of g-ases absorbed in the moisture thrown off from the egg-; and if, there- fore, this moisture is promptly frozen on the cooling- pipes, or absorbed by chemicals, the poisonous gases and products of decomposition are very largely ren- dered harmless. This is also true of the germs which produce mold and hasten decay, which are ever present in the atmosphere of a storage room, being carried to a considerable extent by the water vapor in the air, along with the foul matter of various kinds referred to. If the vapor laden air surrounding an egg is not removed and fresh air supplied in its place, the air in the immediate vicinity of the egg gets fully charged with elements which will produce a growth of fungus on its exterior, affecting and flavoring the in- terior the flavor varying in intensity, depending on how thoroughly impregnated with fungus-producing vapor the air in which the egg is kept may be. In short, then, circulation is of value because it assists in purifying the air. It should be kept up so that the air may be constantly undergoing a purifying process to free it from the effluvia which are always being thrown off by the eggs, even at very low tem- peratures. It has been suggested that a brisk circu- EGGS IN COLD STORAGE. 31 lation of air which will keep in motion the whole volume of air in the storage room will have a purify- ing- influence independent of any moisture absorb- ing- capacity, but no satisfactory reason has been assig-ned. There may be such an influence opera- tive when the air is mechanically circulated. If so, there seems to be no scientific or practical explana- tion of it. Manv patents have been granted for improve- circulation in A natural ice ments in storag-e rooms or refrig-erators using- ice only refrigerators. for a cooling- ag-ent; house refrig-erators, refrigerator cars and refrigerator buildings are represented in number about in order named. A large portion of the patents granted have been on claims for the improve- ment of circulation, and this is the keynote of what- ever success has been attained by the various sys- tems which use ice only for cooling. As any system of cooling whereby the air is caused to circulate in contact with melting ice is now quite generally re- garded as obsolete for the successful refrigeration of eggs for long period storage, a discussion of the merits of the various devices applied to this work will be omitted.* It may be said to their credit, how- ever, that the builders of ice refrigerators have orig- inated ideas on circulation which have been of much value to the present-day refrigerating engineers, and there are still those who may obtain good information from this source the provision for circulation (or rather, lack of circulation) in a few of the new me- chanical cold storage houses being simply ridiculous. In the more progressive mechanically refrigerated houses there are a number of devices, which have been introduced for assisting natural gravity air cir- culation, also the various modifications of the me- * The above must not be construed as condemning- the use of ice as a refrigerant when rightly applied. The writer has in successful operation a sys- tem of gravity brine circulation, cooled by ice and salt, with which he will under- take to produce at moderate expense any possible results in refrigeration down to a temperature of 15" F. 32 KGGS IN COLD STORAGE. Questions rel atinar to circulation. Answers to Query 1. chanical forced circulation system. Some of these will continue to gain favor because of the improved results obtained by their use. The main requisite in any air circulating- system is an ability to cause an equal distribution of the moving- air, as it comes from the moisture absorbing- surfaces, forcing it uniformly to all parts of the room and compelling- it to flow throug-h and around the. piles of stored g-oods. As a secondary consideration may be mentioned the equal- ization of temperature and humidity in all parts of the room. The writer is somewhat biased in favor of forced circulation, having- developed a very complete system on this line, with some new features. Aside from a matter of economy of space and operation, the system employed matters little, if an effective cir- culation is produced. The questions bearing 5 upon circulation contained in the list of inquiries sent out by the writer are as follows : First. In piping- your rooms what provision was made for air circulation? Second. What difference in- temperature do you notice in different parts of the same room? Third. Do you use a fan or any kind of mechanical device for maintaining- a circulation of air in the rooms? More answers were received on this subject than on the subject of humidity, but not exceeding- one- third contained tangible replies to all three inquiries. Several of the answers confounded circulation with ventilation, as before alluded to. Question 1, in par- ticular, was badly neglected, indicating, no doubt, that no provision was made for circulation in a majority of cases. The common device in use for causing air to circulate more rapidly over the cooling coils, when they are placed directly in the room, is some form of screen, mantle, apron, false ceiling or partition, as illustrated in Figs. 3, 4 and 5. Many of these have been put up after the house has been in operation for EGGS IN COLD STORAGE. 33 some time, and are very crude affairs, applied in all conceivable combinations with the pipe coils. In some cases canvas curtains, or a thin wooden screen, have been suspended under ceiling- coils with a slant to cause the cold air to flow off one side, and with sur- prising" improvement to the room, considering- the simplicity of the device. Forced circulation with a complete system of distributing- air ducts is coming into g-eneral use, as the meritsof this way of producing circulation are better understood and appreciated. Query 2 was answered more generally, but that Answers to some of the answers were mere guesses, or state- ments made without testing, is very evident, as they state that no difference was noticed in different parts of the same room. With open piping or gravity air circulation, this is an impossibility it is only possible with a perfectly designed forced circulation system. In contrast to this claim some answers state a differ- ence in temperature of as high as 4 F. to 5 F., but most answers show a difference of 1 F. to 2 F.; a few ^ F. to 1 F.; and, still others, as before stated, none at all. A marked variation of temperature in different parts of a room, while in most cases caused by defective circulation, is due sometimes partly to location of room as to outside exposure, proximity to freezing rooms, character of the insulating walls, etc. An egg room placed over a low temperature freezing room will show more variation between floor and ceiling than when located over another egg room, conditions being otherwise the same. Where this arrangement occurs, and the egg rooms are operated on a natural gravity air circulation system, eggs may be frozen near the floor, when a thermometer hanging at the height of a person's eyes would read 30 F. or above. Even with the very best insulation, the result of this very common arrangement is a defective cir- culation and more or less variation in temperature between floor and ceiling. 34 EGGS IN COLD STORAGE. Answers to Query 3. Gravity air circulation. In reply to Question 3, about a dozen state that they are using- some form of mechanical forced cir- culation. The advantages of this method will be discussed quite fully later on. About double this number are using- the small electric fans. These also will be treated in the discussion of mechanical air circulation in another chapter. As air circulation is a somewhat neglected subject, and comparatively few have experimented enough to have positive opinions, based upon practical expe- rience, reg-arding- the merits of different devices and methods, some of the more prominent and successful ones are illustrated and discussed in this article. In considering- the following- outlined arrange- ments of piping- in the storag-e room and the various locations of screens, partitions, etc., in combination with the coils, for the purpose of separating- the warm and cold currents of air (the one on its way upward from lower part of room to the top of cooling- coils; the other downward from cooling- coil toward floor), the principle on which this movement of air operates should be noted, so that the underlying- law may be understood. The cause of a circulation of air in a storag-e room with direct piping- is a variation of temperature, which causes a difference in weig-ht of the air in different portions of the room. The air in the immediate vicinity of the pipes is cooled to a lower temperature than in the balance of the room, causing- it to drop toward the floor by reason of its greater specific gravity what is designated as gravity air circulation. Just as long- as the flow of the refrig-erant is main- tained within the cooling- pipes, the air will circulate by the action of gravity, the lig-hter warm air in top of room descending- to replace the air in contact with pipes, which falls, as cooled, toward the floor. Should the refrig-erant passing- through coils be shut off, the cooling effect is checked, and as a result air circula- EGGS IN COLD STORAGE. 35 tion over the pipes ceases. This should make plain the fact that uniform temperatures in all parts of the room are not even an approximate possibility in any room depending- on natural gravity air circulation. It may also be observed that the eg-g-s exposed to the flow of cold air near bottom of coils will stand in a dryer and colder atmosphere than those in top and center of room. Fig-. 1 shows an outline sketch of piping- suspende from the ceiling- of a room the most unscientific way possible for a room to be piped, as it provides for no * " ) ' f j*f v j ^ ^ J ; ( V j ^ s air circulation whatever. The only possible reason why air will circulate over pipes in this position is be- cause of the fact that the whole ceiling- is not covered by pipes, which allows of a partial circulation, as shown by the arrows. The volume of circulation in the lower half of room is practically nothing-. It is larg-ely confined to the top of room, the lower part being- cooled by conduction and radiation almost en- tirely. It may be asked : How can a room be cooled by radiation? In the same way that a room is heated by radiation, except that in cooling- a room the heat is radiated_/>wft the objects in the room, and not to them, as when heating-. This gives us ample reason why a room should be cooled by circulating- the air over 36 EGGS IN COLD STORAGE. Open side wall Piping. frozen surfaces located outside of the room, or at least in a position so that no radiation or conduction can occur. The use of insulated screens or mantles, as shown in Figs. 3, 4. and 5, is recommended as being- superior to any arrangement of open piping-; but, of course, it is not equal to forced circulation, in which the pipes are located outside of room entirely. Fig-. 2 shows another very common and faulty arrang-ement of piping for cooling an egg room. The only improvement over the arrangement shown in Fig. 1 is that it allows of a moderate action of gravity K f ( f \ \v near the coils, as shown by the arrows. It is open to the same objection on the ground of conduction and radiation as No. 1, but to a lesser degree. The coils are placed a few inches out from the walls, to allow the air to circulate around the pipes freely, and to provide room for an accumulation of frost. The top of the coil should be quite close to the ceiling. If the coil is placed, say midway between floor and ceiling (unless it covers nearly the whole space), it is sure to result in the air becoming stratified, a warm layer of air in top of room resting on a colder one near floor, perhaps to an extent so great as to cause a difference of 10 F. in temperature between floor and ceiling of room. A case with exactlv these conditions is on EGGS IN COLD STORAGE. 37 record. Another very bad arrangement of side wall piping- came to the notice of the writer recently. A room exceeding- fifty feet square was piped completely around from floor to ceiling with the exception of the doors. Circulation could penetrate but a compara- tively small portion of the space in this room, and in a large area of the central portion the air was conse- quently very foul, and mold and must were rampant. Fig. 3 gives us the first primitive improvement A over open coils, and it is along step in the right direc-pip in tion, but it fails to take care of the center of the room, /'/> f/j. especially near the ceiling. The usefulness of this device consists in its ability to increase the velocity, and consequently the volume of air passing over the cooling coils. The increased velocity of air causes it to cover a greater area, and spread toward the center of room further. The apron or screen used before the coils should be constructed of any moderately good non-conductor. Separating the warm and cold currents of air increases the draft, on the same prin- ciple that a fire burning in a flue creates a greater suction or a more rapid displacement of air than when burning in the open. Fig. 4 is simply an addition to No. 3, of a false ceiling or curtain extending well out toward the 38 KGGS IN COLD STORAGE. Gay's system of box coils. center of the room. This obliges the circulation to spread so as to cover a large portion of the cross-sec- tion area of the room, as indicated by the arrows, but has the effect of reducing its volume to some extent. This ceiling apron should have a slant of not less than one foot in ten. It occupies some considerable space, but is richly worth it. The opening into outer edge of apron in center of room need not exceed three inches in depth in most cases, and, as some space must be left at the top of room for air circulation with the wall coils, without ceiling apron, not much space is wasted by its addition. Fig. 5 gives us an entirely different arrangement of piping, but with essentially the arrangement of aprons shown in Fig. 4. This is the system advo- cated by Mr. C. M. Gay on page 106 of the August, 1897, number of Ice and Refrigeration, and the writer believes it to be the best idea for air circula- tion of any having pipes directly in the room. The following is quoted from Mr. Gay's description: " Upper pipes of box coils should be about ten inches below the ceiling of the room, to prevent sweating. When brine or ammonia is turned into these pipes (as shown in Fig. 5), the cold air around the pipes seeks an outlet downward and passes between the EGGS IN COLD STORAGE. 39 false partition and the side wall of the room, thus displacing- or pushing- along- the air in center of room, the cold air naturally seeking- the lowest point and the warm air the hig-hest point, each by reason of its rela- tive gravity. Thus as the cold air falls from the cool- ing- surfaces it is replaced by the warm air from hig-hest point in center of room. This secures a natural circulation and a dry room, there being- no counter-currents nor tendency to precipitate moisture on walls or ceiling-." Fie-. 6 is the St. Clair or pipe loft system, which st. ciair, or i_ 1-jj j i j t. j Pipe loft has been applied to many remodeled overhead ice system, cold storag-es, by placing- the pipes in a part of what formerly was the ice space, and, in some cases, using- the original air ducts for circulation. The sketch here shown represents one room only, but as many as five or six different floors have been operated from a single pipe loft, using- one main air duct for the down, and one for return air circulation, each floor having- a connection with the mains in which the flow of air is reg-ulated by g-ates. A better arrang-ement, when more than one floor is to be operated on this system, is to have independent ducts for each room, and the cooling- coils separated likewise; then any room or rooms may be used for other products at any time 40 EGGS IN COLD STORAGE. Size of egg rooms. when free of eggs. This latter arrangement, of course, requires more space and is slightly objection- able on this account. The circulation is more vigor- ous with this system than with any pipe-in-the-room system, depending- on the law that the higher the column of air the stronger the draft, on the same principle that a tall chimney gives greater draft than a short one. It is, therefore, better than any room pip- ing, and has the added advantage of f / being easily shut off from the room, when the weather no longer requires cooling power. The need of keep- ing the air of the room from contact with the frost on pipes will be looked into under ventilation and absorbents. Refrigerator rooms for the storage of eggs should not exceed thirty or thirty-five feet in width. The cross-section illustrations of rooms cooled by gravity air circulation, which have already been illustrated, and the two sketches shown herewith of the arrangement of air distributing ducts used in two systems of forced circulation, are sufficient to show why a room should not be excessively wide as compared to its height. In a wide room it may be seen that the air from cold air ducts, in case^of forced circulation, or from the BGGS IN COLD STORAGE. 41 bottom of cooling- coils in case of room piping-, is required to pass over more eggs in its flow to the return air duct or false ceiling-. The eg-g-s, then, are not all exposed to the same drying- and puri- fying- influence, because the air as it comes from the cooling- coils is at its maximum dryness and purity, and becomes impregnated with moisture and impuri- ties more and more as it flows through the goods. If the length of piles of goods is great from side to cen- ter of room, the eggs in top and center of room will be exposed to air which is much more impure and moist than the eggs first exposed to the flow of air directly from cooling coils. This applies more especially to the gravity systems of air circulation. With forced circulation, the air moves probably three or four times as fast as when a gravity system is used, con- sequently the air in top and center of room does not carry the amount of impurities that it does if depend- ing only on gravity for its motion. This fact in itself is a very good reason why forced circulation is supe- rior to any gravity system. It has been claimed that eggs will lose weight by shrinkage more rapidly when stored in a room iH which the air is circulated by mechanical means than in a room operated on the gravity air circulation prin- ciple. This assertion is based on the assumption that the air is circulated at a much higher velocity when forced circulation is employed, and is only partly true because no account is taken of humidity. If the humidity was the same in both cases, the claim would be strictly true. Every intelligent housewife knows that linen hung in the open air to dry, will be freed of moisture quicker when a strong breeze is blowing, than when the air is nearly still. The same principle applies moderately to eggs in a refrigerator room. With the same per cent of moisture, the more rapid the circulation the greater the evaporation from the eggs; but if the facts were known, it would be 42 KGGS IN COLD STORAGE. found in every instance where trouble from excessive shrinkage of the egg meat was experienced, that no attempt was made to regulate humidity. It is as easy to control humidity as it is to control temperature, and with no bad effect on the other conditions in the storage room, if we go about it in the right way. Ventilation and the use of absorbents are agents which can be utilized for this purpose. toie With a vigorous circulation of air, an egg room may circulation. be maintained at a humidity which would be disas- trous, if only a sluggish circulation was operative. Why? Because a brisk movement of air around the eggs removes the moisture and impurities as fast as given off by the eggs. They are not allowed to remain in the vicinity of the eggs to work mischief, but are promptly hurried off to the cooling coils or absorb- ents, where they are, for the most part, rendered harmless. This seems to explain how eggs may be carried sweet, and with very little evaporation, when a well distributed forced circulation of air is employed. With any gravity system, the circulation of air can- not be controlled, because depending on the tempera- ture of refrigerant flowing in the pipes for its velocity; and as the temperature of refrigerant is regulated to correspond with outside weather conditions (lower in warm weather and higher in cold weather) the velocity of circulation is not constant being least in the cold weather of fall, when it is most needed. With a good system of forced circulation installed, the problem, then, is to proportion the circulation of air to the humidity. We might take our humidity at the degree which would come naturally, if no attempt were made to control it, and speed our blower up or down to pro- duce a circulation to match, but it would probably be best to provide a circulation which would handle a large volume of air at a brisk speed, and raise our humidity to as high a point as would be safe. Refer- ring to the table of correct humidity given in Chapter EGGS IN COLD STORAGE. 43 II, page 23, it will be noted that an arbitrary percentage is given for each temperature. These are the most desirable percentages of air moisture for average conditions of circulation, as when using the most scientific forms of gravity air circulation during warm weather. When using a good system of forced circulation, these percentages may be in- creased moderately. Exactly how much will depend on conditions, and can be told only by trial, but it will be much greater in proportion at the high tempera- tures, ranging from 2 per cent or 3 per cent on the low, to 7 per cent or 8 per cent on higher temperatures. Before taking up the forced circulation systems Electric fan in egg room not proper, the electric fans used in so many large houses desirable. will be considered. These little fans are a four to six-bladed disk fan, from twelve to eighteen inches in diameter, attached directly to the shaft of a J/s or ^ -horse power electric motor. /The wires supplying the electric current to the motor are usually con- nected to the socket for an ordinary incandescent lamp. Electric fans are usually placed on the floor in the back end of alleyway, or in an opening in the piles of goods, creating a draft of air from one ex- tremity of the room toward the other. As the air from the fan will follow a path of least resistance, the circulation resulting from their operation is largely confined to the alleyways or openings in the piles of stored goods it does not penetrate through and be- hind the piles of eggs. It may be readily observed that this is of doubtful utility, and may at times lead to positive harm by causing a condensation of mois- ture upon goods as a result of the comparatively warm, moisture laden upper strata of air coming in contact with the flow of cold air from the cooling pipes. Electric fans have also been utilized to propel the air from the cooling pipes, for which purpose they are placed in an opening in a screen or mantle cover- ing the pipes, forcing the cooled air outwardly into the 44 EGGS IN COLD STORAGE. room. In any other position, they are only useful as a "talking* point," as it is likely to impress a prospective customer favorably with the cooling- power of a refrig- erator, to allow him to stand for a few seconds in the breeze created by one of these higii-speed fans. The use of electric fans has been adopted to an extent not warranted by the results possible to attain with them, and their use will no doubt be gradually discontinued as the fallacy of the idea becomes apparent. Primitive The first svstem of true forced circulation to con- torccQ a, ir * circulation. s ider is not illustrated and needs no sketch to explain the working- of it, as there are practically no distribut- ing- air ducts, the cold air being- forced into the room at two or three larg-e opening's, and taken out in the same way. There are two prominent houses using an air system constructed on these lines, one having the cold air inlet near floor and warm air outlet near ceiling-, the other having both cold and warm air open- ings near ceiling. No distribution of circulating air of any consequence is provided, the idea being simply to cool the room by forcing in air which has been cooled by coming in contact with cooling pipes located outside of the rooms. The cold air is taken in at one extremity of room and the warm air out at the other, or the cold air is taken in at ends of room and warm air out at center, or the reverse. This is what may be called a primitive form of forced circulation, and is quite similar to the systems of indirect steam heating as first employed. It needs no argument to show that a room equipped in this way has varying degrees of temperature, humidity and circulation, depending on the remoteness or proximity to the direct route be- tween cold air inlet and warm air outlet the air mov- ing through the area of least resistance, which is usually along the center alley of room. Linde-British Fig. 7 shows the arrangement of ducts for air air-circulation 3 . system. circulation used in the Linde-British air system; a a, cold air ducts; b b, warm air duct. This system of EGGS IN COLD STORAGE. 45 refrigeration originated in Europe, and has found favor to some extent on this side of the water, three houses known to the writer being- operated on this system. Mr. E. H. Johnson describes the apparatus used in cooling, purifying and circulating the air on page 96 of the February, 1898, issue of Ice and Refrig- eration. This consists essentially of a tank containing brine, which is cooled by direct expansion piping. Slowly revolving in the tank, with a portion of their surface exposed above the surface of the brine, are large metallic disks. A fan causes the air to circu- late rapidly over the brine moistened surfaces of the disks, and the moisture is extracted, and impurities and odors absorbed by the cold brine. In a modifica- tion of this apparatus the direct expansion coils do the cooling and take the place of the disks as well. The coils are exposed to the air circulation, and the brine is pumped over them in a shower, a shallow pan or tank being provided under coils as a reservoir and recep- tacle for the brine the same brine flowing over coils again and again. It has been claimed for this system that almost any product can be stored in different rooms, all of which were fed by the same air circuit and cooling apparatus, without any injury to the most sensitive. A statement of this kind must first be 46 EGGS IN COLD STORAGE. proven before we can accept it. There is no doubt, however, but that some good features are embodied in above described apparatus. It is well known that water, and especially salt water, has a great affinity for impurities contained in the air, and when the air is circulated in contact with the brine, as in the Linde system, many of the gases and impurities common to a storage room are absorbed. That they are ab- sorbed to any greater extent than when the moisture is simply frozen on the pipe coils, the writer is not prepared to assert. An objection to this brine or wet surface air cooling is the liability of trouble when brine gets polluted with impurities. After some use the brine will no longer act as a purifier, and in this condition will contaminate, rather than purify, the air. If attended to, this trouble can be prevented by a periodical renewal, or by supplying a certain amount of fresh brine at regular intervals and allowing a portion to overflow. In discussing absorbents we will find a description of a device which seems to have all the advantages of the Linde method, and without some of the objections. The location of air ducts as adopted by the Linde- British company seems to call for some attention. It is evident from their location that gravity is depended upon for a circulation of air near floor, as both warm and cold air ducts are placed on ceiling of room. The flow of air into room is controlled by means of sliding gates, which are adjusted to openings placed five or six feet apart in the air duct. This does not provide a well distributed circulation, as those goods directly opposite openings in cold air ducts will be exposed to a sharp blast of air, while others get practically none. As a result of placing the cold air duct on ceiling, there will be little or no movement of the air near floor, when rooms are filled with goods. Fig. 8 shows a cross-section of a room fitted with a system of air ducts and false ceiling for the circu- EGGS IN COLD STORAGE. 47 lation of air in a cold storage room, which the writer has developed after several seasons' experiment, and which is regarded as very nearly theoretically perfect. In practical working- it gives very superior results, and is believed, by those who are using- it, to be in advance of any other system now in use. By referring- to the sketch it may be seen that the air is forced to cover very uniformly the entire cross-sec- tion area of the room a result not possible with any other device. This is obtained by the use of a false ceiling, b b, perforated at intervals with small holes / v the "Cooper system" of forced air circulation. which covers the whole ceiling of room ; and the side air duct, a a, perforated with small holes on top, bot- tom and sides. The air from cooling coils is forced into ducts, a a, and flows out through the perforations. Passing through the piles of eggs, as shown by the arrows, the air moves upward through the perfora- tions in the false ceiling, and thence through space between false ceiling and ceiling, to cooling coils again. This circulation is actuated by an exhauster, or blower, preferably located on the main cold air duct, between the cooling coils and cold air ducts, a a. This has a tendency to put the egg room itself under a slight pressure, and the coil room under a vacuum. In this way the air leakage from outside, if there is 48 EGGS IN COLD STORAGE. any, is into the coil room, and not into the storage room. The perforations for outflow of air from cold air duct, a a, are twice as numerous on bottom as on the top, and some are placed in the face or side of duct also. The perforations are comparatively small holes placed quite near tog-ether, obviating- all strong- drafts, and at the same time insuring- a very pene- trating- circulation which will not allow of any dead corners. The false ceiling- is perforated likewise, the holes being- most numerous throug-h the center of room at farthest point from cold air ducts, and more widely separated as they approach sides of room directly over cold air duct. If air ducts are correctly proportioned, the perforations properly located and of correct size, and eg-g-s are piled uniformly from side toward center of room, the air is forced to percolate throug-h the piles of eg-g-s where its presence has such a salutary effect, for reasons already discussed. The exhauster for handling- the air can be placed in almost any location handy to power, and the air conducted to it, but a more desirable arrang-ement is a direct con- nected or a direct belted electric motor. Then the fan may be placed advantageously to get direct and shorter air ducts, saving both space in the storage room and expense in construction. A saving of space can be obtained by using this tiois tern a ~ system of air circulation, amounting in some cases to fully 10 per cent of the total space cooled, and a sav- ing of 5 per cent can be had in any house, if skill and care are used in arranging cooling coils and air ducts. Where rooms are moderately high the space over a hallway or corridor may be utilized for cooling coils. As the cooling coils are located entirely outside of the storage room proper, the room itself can be filled with goods snug up to the false ceiling at the top and against air ducts on sides. The side ducts and false ceiling only occupy about two inches of space in their respective locations, so the space occupied by the air EGGS IN COLD STORAGE. 49 system is very small. Storage men will at once ap- preciate that a saving- of even 5 per cent in space adds that much to the profits of the season's business, as it is as expensive to cool vacant space as it is to cool it when occupied by goods. As an objection to the forced circulation system, g. fans it has been urged that the expense of running fans continuously for handling the air was so large as to be a serious item of expense. With a well constructed apparatus and a large light weight fan wheel running at a slow speed, the air in a room containing 15,000 cubic feet, which will store about 5,000 cases of eggs, may be circulated with an expenditure of effort not exceeding one-half a horse power. The selection of a fan for propelling the air is of considerable moment when installing an air circulat- ing system in a cold storage room. Fans also play an important part in handling air for ^ventilating, and the merits of the different kinds and forms of fans will be discussed under "ventilation." CHAPTER IV. VENTILATION. value of T N discussing- humidity and circulation, it has been ventilation. J 1 explained how a large portion of the gases of de- composition and impurities of various kinds, which are incident to the presence of perishable products in cold storage, are carried by the moisture existing- in the air, and that when this moisture is frozen on the cooling pipes, or absorbed by chemicals, the foul mat- ter is largely rendered harmless. It may now be noted further that even with a good circulation and ample moisture absorbing capacity, there will still be some impurities and gases, detrimental to the wel- fare of the stored goods, which have little or no affin- ity for the water vapor in the air, and consequently accummulate in the storage room. Ventilation is necessary to rid a refrigerator room of these perma- nent gases. The introduction of a large volume of fresh air is not essential, however, for the purpose of purifying rooms in which eggs are stored, because the accumulation of permanent gases in an egg room is quite slow, comparatively (as in rooms where well ripened fruit is stored); but a small supply of fresh air continuously, or at regular intervals, is of much benefit. Ventilation by This subject of ventilation for refrigerator rooms has been very much talked about recently, but about which really little is known, so far as any tangible in- formation is concerned. Some of the more progress- ive cold storage managers have given some attention to this part of the business, but many of the largest and best known houses do not ventilate their rooms at all, except perhaps during the winter or spring, when rooms are aired out for the purpose of whitewashing. In some cases the change of air incident to opening and closing of doors, when goods are placed in stor- age or removed therefrom, is relied on to supply ven- 50 EGGS IN COLD STORAGE. 51 Illation. This is quite inefficient, because eggs are mostly stored during two or three months in the spring, and removed from storage during the fall and winter, leaving three or four months when no fresh air of consequence can penetrate to the room, except as the doors may be opened for the purpose of taking the temperature of the room. Furthermore, this kind of ventilation during the warm weather of sum- mer and during a large part of the spring and autumn months is worse than no ventilation at all. Some stor- age men even take so radical a position on this matter of opening doors during warm weather, as to insist that the door shall not be opened for the purpose of reading the thermometer. A double window is placed in the door of each room, with the thermometer hang- ing so that it can be read from the outside without opening the door. While the writer has not practiced this method, it seems to be a good idea, and it is cer- tainly preferable to ventilating the room through doors which open to the outside air. When doors into rooms open into a corridor, the evil can be partly prevented by piping the corridor overhead, so that the moisture and impurities may be taken up in this way; but opening the door or window of a storage room directly to the outside air when the temperature outside is materially higher will always result in more or less bad effect on the goods, as a result of the water vapor, in the warmer incoming air being con- densed on same. Another source of ventilation similar in its results to the opening of a door or window is that resulting from the leakage of air directly into the storage room, through the pores and crevices in the walls around the doors and windows, etc. leakage of air literally air that gets in when everything is supposed to be closed. The amount is usually imperceptible, but is enough in some houses to be a serious detriment to the quality of work done. In small houses with large outside ex- 52 EGGS IN COLD STORAGE. posure and poor insulation this air leakage is consid- erable, but in the big- refrigerators of several hundred thousand cubic feet capacity, and with thorough insu- lation, it is reduced to practically nothing. The loss of refrigeration caused by air leakage, while of some importance, is of small moment beside the bad effects resulting from the moisture and impurities brought in by the warm air from the outside. The value of prime, tight insulation, as a conserver of refrigera- tion, aside from a matter of keeping out the warm, moist air, is well enough understood not to need re- peating here, but a word about windows and doors is properly in line with the present discussion. use of windows Rather than consider what might be a good way for eg-g- rooms. -" of placing windows in a cold storage building, their use should be discouraged. Even with four or five separate glass, divided by air spaces, and with all joints set in white lead, the loss of refrigeration is large. It is also very difficult to fit insulation around the window frame so as to make a good job; and even if a passable job were practicable, the expense of putting in windows is sufficient to condemn their use. The increased fire exposure is of some consequence, too, and with the low cost of electric light, windows should not be thought of for cold storage work. Barring the small amount of heat given off, the incandescent elec- tric lamp is an ideal device for lighting cold storage rooms, as the air is not vitiated as when using gas, kerosene or candles. Doors which will shut tight, forming a nearly per- fect air seal, with a small amount of pressure, have long been wanted for cold storage rooms. Most of the ordinary bevel doors, either with or without packing on the bevel, will not shut even approximately tight; and in operation nine out of every ten stick and re- fuse to open except after many persuasive kicks and surges we all know how it is. While having no in- terest in furthering the sale of the Stevenson door, EGGS IN COLD STORAGE. 53 which will be advertised in Ice and Refrigeration, the writer believes it to be head and shoulders above any- thing else in this line, and does not hesitate to recom- mend it to those wanting- a door which will prevent air leakage. The price is very reasonable, consider- ing- the excellent material and fine work put into its construction. The slig-ht additional cost over the common door will be quickly saved, by reason of its quick action opening- instantly when the lever is grasped. Having- g-ot into the subject of air leakag-e, we may as well see how it is caused and why it must be airleaka ^ e - g-uarded ag-ainst. It is operative from the same law as gravity air circulation, which was explained quite thoroug-hly in the first part of the chapter on " Circu- lation." When the outside air is warmer than that of the storage room, the air in the storage room pro- duces a pressure on the floor and lower part of the room, by reason of its greater weight, and conse- quently it seeks to escape there. If there are open- ings near the floor where the air can flow out, and others at the ceiling -or upper part of the room, the air will flow in at the top and out at the bottom of the room. Reverse the conditions of temperature, and the direction of flow of air is also reversed. That is, when the air outside is colder than the air of the room, the cold air will flow into the room at the bot- tom and the comparatively warm air of the room out at the top. This action is nicely illustrated by not- ing the air currents in a door which is opened into a cold room when the temperature is very warm out- side. The warm air rushes in at the top of door and the cold air of room out at the bottom. In cold weather the direction of air flow will be reversed. Perfect inclosing walls for a cold storage room would be perfectly air tight, as they would be if lined stora ^ e with sheet metal, with soldered joints. The interior conditions would then be under more perfect control. 54 EGGS IN COLD STORAGE. It is hardly necessary to do this (although it has been done in case of some old time houses), as a practically tight job may be had by using- the right materials, well put on. Air leakage may not be ex- actly ventilation, but it is a kind of ventilation which has given the writer some trouble in the past, and does still, consequently the difficulties of operating a house with defective insulation and large outside exposure, and still turn out first-class eggs, are very thoroughly appreciated. 4Jn f m r uIt e be la ' Methods of ventilation which are permissible when applied to the work of supplying fresh air to ordinary structures are generally dangerous when used to ventilate cold storage rooms. The problem in ventilating non-insulated structures is merely the supplying of fresh air from the outside without caus- ing a marked change in the temperature, and without creating strong drafts. Air for the ventilation of refrigerator rooms, during warm weather, must be of very nearly the same temperature and relative humidity as the air of the room to be ventilated, and free from the germs which hasten decay and cause a growth of fungus on the products in storage. If a door or window of a storage room is opened directly to the outside atmosphere, there will be little or no circulation of air into and out of the room when the temperature outside and in is about the same, unless the wind should be favorable. As we cannot ventilate in this way when the air outside is colder than the storage room, on account of freezing the eggs, and the introduction of fresh air, which is warmer than the storage room, is not permissible, for reasons already given, the matter reduces itself to not ventilating at all during warm weather (which most houses prac- tice), or of properly cooling and purifying the air be- fore forcing it into the storage room. It will bear repeating that it is positively bad practice to allow air from the outside to get into an egg room during the EGGS IN COLD STORAGE. 55 summer months, also during* a large portion of the spring- and fall months, unless cooled and purified first. The fact that we cannot see the moisture de- posited in the form of beads of water, or floating- in the air in the form of fog- or mist, does not indicate that it is not present. The sling- psychrometer, de- scribed in discussing- humidity, will give an accurate indication of the result of this unscientific method of ventilating-. Any natural means of handling- air for ventilation *}Jf Bri ** s is inaccurate and inoperative, or it may be positively ventllatlon - harmful, except under favorable conditions. If de- pending- on natural gravity for ventilation it will be g-uesswork, to a greater or less extent, because de- pending on conditions which vary with the season, temperature, direction and force of the wind, etc. The late Robert Brig-g-s, an authority on ventilation, makes a concise statement of the advantages of using fans for ventilation, in his " Notes on Ventilating and Heating."* He says: "It will not be attempted at this time to argue fully the advantages of the method of supplying air for ventilation by impulse through mechanical means the superiority of forced ventila- tion, as it is called. This mooted question will be found to have been discussed, argued and combated on all sides in numerous publications, but the con- clusion of all is, that if air is wanted in any particular place, at any particular time, it must be put there, not allowed to go. Other methods will give results at certain times or seasons, or under certain con- ditions. One method will work perfectly with certain differences of internal and external temperature, while another method succeeds only when other differences exist. . . . No other method than that of impelling air by direct means, with a fan, is equally independent of accidental natural conditions, equally efficient for a desired result, or equally * Proc. Am. Soc. Civil Engineers, May, 1881. 56 KGGS IN COLD STORAGE. Plenum vs. vacuum method of ventilation. Advantages of the plenum or pressure method. controllable to suit the demands of those who are ventilating-." There are two general methods, with some modifi- cations, for handling- air for ventilation: The plenum or pressure method, in which the fresh air is forced into the room ; and the vacuum or exhaust method, in which the foul air is drawn out. The exhaust method is to be avoided for ventilating- cold storag-e rooms, for reasons which we shall see presently. With this method, sometimes the exhaust steam from an engine is utilized to induce a draft of air upward from storag-e room, by heating- the air in a stack or ventilation flue connected at its lower end with the room to be ven- tilated. In some cases no provision is made for an in- flow of fresh air, in which case it will seep in at every crack, crevice and pore (by reason of the partial vacuum created by exhausting- the foul air out), bring- ing- a load of moisture and g-erms of disintegration into the storag-e room. This exhaust steam method is no different in its result than if a fan were placed so as to draw the air out of the storag-e room under conditions which are otherwise the same as described in connection with the exhaust steam method. Should we provide an inlet for fresh air, throug-h proper ab- sorbents, the same law would be operative, only to a lesser degree, as a partial vacuum must, in any case, be created before the air from outside would flow into the room, tending- to the dang-erous air leakag-e already fully discussed. The plenum or pressure method is by far the best for our purpose. The air should be forced into the room by a fan, after first properly cooling-, drying and purifying- it. An outlet for the escape of the foul gases which it is desired to be rid of, should be pro- vided near the floor, as these gases, by reason of their greater gravity, tend to accumulate in the lower part of the room. It will be observed that forcing the fresh air in creates a pressure inside the room, EGGS IN COLD STORAGE. 57 and if there is any air leakage, it will be outwardly from the room exactly the way we want it to go. Having- brought our subject to the point where it is found that the best way to ventilate is by the use of fans forcing- the air into the storag-e room, we will determine what type of fan is best adapted to our needs. What is said of fans for ventilation is equally true if they are to be used for forced air circulation, described under head of circulation. It is admitted by a majority of experts on air mov- ing- machinery that the disk or propeller wheel ty pe type of fan - of fan, throug-h which the air moves parallel to the axis of fan, is not efficient or desirable for work where the air has to travel throug-h a series of tortuous air ducts, as in the forced air circulation system for cold storag-e work, or for ventilation purposes where there is some resistance. Where any resistance of import- ance is encountered, the disk fanjnust be driven at a hig-h rate of speed, and at an immense loss of power, to compel it to deliver its full quota of air. Another dis- advantage of the disk type is the difficulty of belting to the shaft, or of g-etting- power to the fan in any form, if it is inclosed entirely in an air duct. The disk type will therefore be dismissed, and the well known centrifug-al, or peripheral discharg-e fan taken up. This type of fan draws the air in at its center Advantages of J r the centrifugal parallel to the shaft, and delivers it at rig-ht ang-les the shaft at the periphery or rim of the fan wheel, the law g-overning- its action being- the well under- stood centrifug-al force, which is commonly illustrated when we see the mud fly from a bug-g-y wheel or the water off a grindstone. The advantag-e of these fans over the disk type is that the centrifugal action set up by the rotary motion of the fan is utilized to give velocity to the air in its passage over the fan blades. In the selection of a fan for the purpose of forced cir- culation in the storage room, or for forcing in fresh air for ventilation, it should be noted that a large slow 58 EGGS IN COLD STORAGE. running- fan wheel is very much more economical of dtffertntspe a eds power than a small fan running- at a hig-h rate of speed, both doing- the same amount of work. The loss of ref rig-eration, too, in a rapidly moving- fan, is of conse- quence, because the air is warmed by impact with the blades. The proportion of power saved by the use of a larg-e fan running- at a slow rate of speed, rather than a small fan running- at a hig-h rate of speed, both de- livering- the same amount of air, is almost phenomenal, and does not seem at all reasonable at first view. The volume of air delivered by a fan varies very nearly as the speed, while the power required varies about as the cube of the speed. That is, doubling- the speed doubles the volume of air, while the power required is increased eig-ht times. We will take a specific case. A 45-inch fan wheel, revolving- at a speed of 200 revo- lutions per minute, delivers, say, 5, 000 cubic feet of air per minute, and requires but one-quarter of a horse power to operate it. If the speed is increased to 400 revolutions, the volume of air delivered will be only about 10,000 cubic feet, while the power required to drive it will be raised to two horse power. These fig-ures are theoretical, but within certain limits are approximated in practice. LOSS of power p or use [ n co id storage work the objection com- from excessive J fan weights. mon to nearly all the air moving- machinery found listed by the manufacturers is the seemingly unnec- essary amount of metal used in its construction. The heavy weig-ht of the fan wheels, and the larg-e diameter of shaft necessitated by such weig-ht, causes much friction on the journals, so that when running- at the slow speeds desirable for cold storag-e work, more power is required to overcome the mechanical friction than is actually required to move the air.* *Having been unable to find a fan wheel well suited to the requirements of cold storage duty, the writer has designed and constructed a line of fan wheels especially for slow speeds, which are amply strong and capable of moderately high speeds, when necessary, but are very much lighter than most fans on the market, and consume proportionately less power in mechanical friction. EGGS IN COLD STORAGE. 59 No doubt the high speeds necessary for some work have obliged the manufacturers to make their fans amply strong- for the highest speeds, consequently they are not economical for the slower speeds. It would not be appropriate for a person to fan himself with a dinner plate it would do the work, but would not be economical of power. So far we have found out what kind of ventilation is not desirable, and have an inkling- of what kind would be desirable. The question before us now is to properly treat the air before introducing- it into the storag-e room, so that it may be fresh /. 26 CORTLANDT ST., N. Y. ADVERTISEMENTS EUGENE T. SKINKLE ("THE BOY") lice flftaktri anb IRefrioeratlng Engineer ROOMS 30 AND 32 177 LA SALLE STREET CHICAGO, ILL. Plans and specifications for Ice Making and Refrig- erating establishments, and consultation in relation to buildings, machinery and apparatus, alterations and repairs. IReferences: BIRMINGHAM ICE FACTORY CO., Birmingham, Ala. CITY ICE MANUFACTURING CO., Chicago, 111. LITTLE ROCK ICE CO., Little Rock, Ark. EAST ST. LOUIS ICE AND COLD STORAGE CO., E. St. Louis, 111. KINGSTON ICE MAKING CO., Limited, King-ston, Jamaica, West Indies GEO. CHALLONER'S SONS CO., Oshkosh, Wis. EL RENO ICE AND COAL CO., El Reno, Okl. MONROE CATERING CO., Chicago, 111. KING'S RESTAURANT, Chicago, 111. AMERICAN RESTAURANT, Chicago, 111. And Many Others. Hce flDafeitiQ anfc IRefrigeratiriQ Supplies AD VKR TISEMENTS The Recognized Authority in all Cold Storage Matters. A MONTHLY REVIEW OF THE ICE, ICE MAKING, REFRIGERATING. COLD STORAGE AND KINDRED TRADES. SUBSCRIPTION PRICE In United States, Canada and Mexico, . . - . In all other countries, . . PAYABLE IN ADVANCE. $2.00 per year 3.00 per year H. S. RICH & CO. 206 Broadway, NEW YORK PUBLISHERS 177 La Salle Street, CHICAGO Also publishers of the following Standard Rooks on Cold Storage, Ice Making and Refrigeration: Gompenft of /Ibecbanfcal IRefrigeration By PROF. J. E. SIEBEL. PRICE. PREPAID. CLOTH, $3.00; MOROCCO. $3.50. The only work treating- of all the various branches of theoretical and applied refrigeration, and will be found to contain a larg-e amount of information which would be looked for in vain elsewhere. practical 1lcc /Rafting and IRefruieratuui By EUGENE T. SKINKLE. PRICE, PREPAID, CLOTH, $1.50; MOROCCO $2.00. Ever} 7 branch of ice making and refrigerating- is handled.in this work, with a view to setting- out the best and most economical practice in the construction and operation of the plant. Ifnfcicattns tbe 1Refn0eratin0 By GARDNER T. VOORHEES. PRICE. PREPAID. CLOTH, $1.00; MOROCCO, $1 50. Treats of the application of the indicator to the ammonia compressor and steam eng-ine, with practical instructions relating- to the construction and use of the indicator and reading- and computing- indicator cards. ADVERTISEMENTS HEADQUARTERS FOR Chloride Calcium Prime white, full strength, packed in 600-pound iron drums. Representing- the largest output in the country, we are in condi- tion to name interesting- prices for car lots or less quantities. PETER VAN SCHAACK & SONS 138-140 LAKE STREET,-CHICAGO. ACCURATE THERMOMETERS. Thermometers bought from us at one time give the same result as thermometers bought from us at any other time. Prof. Marvin's Sling Psychrometer for the exact determination of moisture in the air, is made with the utmost care and is the best of its class. ALL THERMOMETERS MADE BY US ARE GRADUATED AND ETCHED ON THE STEM. Send for a Sample of our Storage Room Thermometer. Price, $1.00 each. SCHNEIDER BROS. 265 Greene Street.. ..NEW YORK Makers to.. .UNITED STATES WEATHER BUREAU. SIGNAL CORPS UNITED STATES ARMY. FISH COMMISSION. ADVERTISEMENTS 25 BEIiOOl ZERO OBTAINED WITH THE FEATURES: MAXIMUM CAPACITY SIMPLICITY HIGHEST ECONOMY- DURABILITY SPECIALLY ADAPTED FOR VENTILATING SYSTEMS FOR PARTICULARS ADDRESS THE CARBONDALE, PA. NEW YORK OFFICE, 1012 HAVEMEYER BUILDING. NONPAREIL CORK Che Ideal Insulation Sheets for Walls Rooms Ceilings. 3- feet Sections for Steam, Brine Ammonia and Water Pipes Ui^b WOtvK! says"THEBOY" in his Practical Ice Making and Refrigerating, page 164, "In the selection of insulating- substances their power to withstand moisture plays an im- portant part in most cases. In this respect Cork is a very desirable material," says Professor J. E. SIEBEL in his Compend of Mechanical Refrig- eration, page 155. The Nonpareil Cork Mfg. Co. 28 QUEEN STREET, LONDON, E* C, ENG. 92 WEST BROADWAY, NEW YORK, N. Y. A D VKK TISKMEN TS Tee and Refrigerating machines FOR CREAMERIES AND PRODUCE DEALERS Refrigerating Machines are rapidly taking the place of ice for refrigerating purposes. A lower temperature can be secured. The cold is absolutely dry. It will pay you to investigate and get estimate on plant. SIMPLE STRONG COMPACT DURABLE ijr LARGEST EFFICIENCY POSSIBLE BE- CAUSE ABSO- LUTELY NO CLEARANCE THE ONLY SMALL MACHINES OF DUPLEX TYPE EQUIVALENT TO TWO INDEPENDENT MACHINES. ONE ALWAYS IN RESERVE AS PROTECTION AGAINST LOSS FROM STOPPAGES AND BREAK DOWNS. Small Plants from 2 to 10 Coits Refrigerating Capacity Our Specialty Estimates Cheerfully and Promptly Given. Write for our Handsomely Illustrated Booklet named ''Cold Making." CREAMERY PACKAGE MANFG. Co, 1, 3 AND 5 WEST WASHINGTON STREET CHICAGO, ILL. Doo and THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN HIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH OVERDUE. T $ '- N E SEVEN DAY fasten fix iru I They ^mplete Wftt 3 1933 1 place, air in either direction. le with f-ewith, hresh- [e d to go on a th nei- thresh- have erhead d corn- in ad- pr so it [mashed trolley. , or all opened re cush- LD 21-50m-l,'33 rush of _ ' ; Complete information, diagrams and illustrations in our circulars. FRICK COMPANY ..ENGINEERS... Established Incorpo 188: E( 288 ies IVERSITY OF CALIFORNIA LIBRARY References and new Ice Machine Circular, describ- ing 1 latest improvements ->"^ " .vinR; Ice arul u.- ,:.,. .eratir.- iild< . fir* class STEAAl oNUiNES, AMMON. VALVES, FLANGES, COILS, etc. CORLISS STEAM ENGINES ICE MAKING MACHINERY, STEAM BOILERS, AMMONIA FITTINGS. FRICK COMPANY, WAYNESBORO, FRANKLIN COUNTY, PA.