Class _IX^S3- Book ,rS £ Copyright N°_ COPYRIGHT DEPOSm SHORT COURSE FOR JANITOR -ENGINEERS BY KENNETH G. SMITH, C. E. THE BRUCE PUBLISHING COMPANY MILWAUKEE, WIS. ^ Copyright 1919 The Bruce Publishing Co, MAR 17 1919 ©CU5 12650 INTRODUCTION The janitor of a school or other public building occupies a position of more responsibility than is usually recognized. He is in a very real sense responsible for the health and com- fort of the occupants of the building under his care. He is also responsible for the economical use of fuel, equipment and supplies. To discharge his duties properly he needs technical knowledge and practical experience. Up to the present time no attempt has been made to formulate and offer any definite course of instruction for the janitor-engineer. Usually verbal directions have been given as to what he is expected to do, sometimes accompanied by a "book of rules." The reasons for these rules he may or may not understand. To add to his difficulties he is often required to take orders from, or at least to accede to the requests of, a number of persons, some of whom, at least, know less about his duties than he does. Again, the entire responsibility of running a plant may be thrown on his shoulders with the one admonition that he "will be held responsible" if anything goes wrong. The work of a janitor is a real vocation requiring, as it does, technical knowledge, a knowledge of human nature and ability to get along with people, and, especially in the schools, the exercise of discipline. There is no reason why the calling of the janitor-engineer should not have a place in the present program of vocational education, and it was in connection with such a program that the following text was first prepared and used. It may serve as a reference book to be read by a janitor during his leisure moments (if he has any) or it may be used as the basis of a definite course of instruction in an evening or day class under a regular in- structor. 3 The text in its present form is not as complete as the writer would like to have it and it is his purpose to revise and extend it as soon as possible. Owing to the fact that fuel saving is now a national issue considerable attention has been paid to this subject. No claim is made for originality. The book is not the result of technical research. It is simply an adaptation of many facts already well known. Acknowledg- ment is hereby made to the many chief engineers and members of school boards and school faculties who have put their in- formation and experience at my disposal as well as to many janitor-engineers whom I am proud to call my friends. KENNETH G. SMITH, M. E. Table of Contents Introduction Chapter I. HEAT — Thermometers — Heat Measurement — Effects of Heat — Questions 7-14 Chapter II. PROPERTIES OF HEAT — How Heat Travels — Circumstances Affecting Heat Travel — Latent and Sensible Heat — Questions. 15-23 ( 'Iiapter III. COAL AND COMBUSTION — Characteristics of Coal — Analysis of Coals — Names and Sizes of Coals — Combustion — Con- ditions Necessary for Combustion — - Questions 24-34 Chapter IV. METHODS OF FIRING — Smoke Prevention — Causes of Smoke — Methods of Firing — Keeping a Good Fire — Special Methods and Appliances — Clinkers — Banking Fires — Questions 35-46 Chapter V . THE HEATING PLANT — Boilers — Washing Boilers — Boiling Out — Scale and Its Removal — Laying up a Boiler — Heat- ing Plant Definitions — Steam Heating Systems — Placing Radiators— Direct and Indirect Systems — Warm Air Systems — Questions 47-58 Chapter VI. GOOD AND BAD AIR — Air Space Requirements — Air Supply Requirements — Air Distribution — Temperature — Types of Ventilating Systems — Types of Fan Systems — Natural and Aspiration Systems — Operation of Fan Systems — Con- clusions of Chicago Commission on Ventilation in Regard to Schoolroom Heating and Ventilation — Questions 59-73 Chapter VII. HUMIDITY — Relative and Absolute Humidity — Humidity Tables — Effects of Humidity — Measuring Humidity — Sup- plying Moisture to Air — Air Washers — Conclusions of the Chicago Commission on Ventilation in Regard to Humidity and Temperature — Questions 74-85 5 6 Table of Contents — Continued Chapter VIII. SWEEPING, CLEANING AND SANITATION — Sweeping and Cleaning — Sweeping — Special Methods of Cleaning — Sani- tation — Health and Cleanliness — Disinfectants and Their Use — Rules and Regulations for Cleaning and Care of School Buildings and Grounds — Rules for Building Care — Winter Care 86-98 JANITOR'S CATECHISM — School Environment 99-100 LIST OF BOOKS FOR JANITOR-ENGINEERS 101 A Short Course for Janitor- Engineers i The duty of a janitor or custodian of a building is to take care of the building and to conserve the health and comfort of the occupants. One of his main duties, especially in the winter time, is to keep the building at a proper temperature ; in other words, to provide heat. Heat, then, is one of the fundamental things for a janitor to understand. Scientists at the present time explain heat by what is known as the kinetic or motion theory. All substances are supposed to be made up of very small particles called molecules. Ac- cording to the kinetic theory of heat, these particles are continually in motion and the faster they move the hotter we say the body is. In very hot steam they are supposed to move very rapidly and comparatively long distances. In cold iron they move more slowly and shorter distances. Our sense of feeling tells us whether this motion is slow or rapid or in other words whether the body is cold or hot. If we de- sire to know accurately how warm a substance is we use a thermometer and do not depend upon our sense of feeling. Thermometers Every janitor is familiar with the fact that "feelings" are not always a safe guide in determining the temperature of a room. One person coming in from the outer air will con- sider the room to be warm; another accustomed to a high temperature will say the room is cold. Hence, the need of the thermometer. There are two common kinds of thermo- meters, the Fahrenheit and the Centigrade. The Fahrenheit, so named from its inventor, is most commonly used except for scientific work. The word "centigrade" means "scale of one hundred" and is so named because there are one hundred degrees on it between the freezing and boiling points of water, as will now be explained. 7 8 A Short Course for Janitor-Engineers Every thermometer must have certain fixed points upon it from which the divisions or degrees are marked. For this purpose we use the freezing and boiling points of water under standard conditions. On a Fahrenheit thermometer the freez- ing point is 32° above zero and the boiling point 180° above the freezing point, or 212° above zero. On a Centigrade thermometer the freezing point of water is marked and the boiling point 100 and there are of course then 100 degrees between them. For this reason the thermometer is called Centigrade, as mentioned above. The word "cent" or "cen- tum" means one hundred and is used in our common words cent and per cent. The boiling point of water is not always 212° because it depends upon the pressure on the water. At sea level, where the atmospheric pressure is greatest, the boiling point is 212°. On top of a mountain, where the at- mospheric pressure is less, the boiling point is lower. In round numbers, we may say that the boiling point drops 1 ° for every 500 feet elevation. In Cedar Rapids, Iowa, the boiling point is about 211°. For practical purposes we consider it to be 212° Fahrenheit or 100° Centigrade. We are so accustomed to thermometer readings that we know instantly when a temperature is mentioned whether we consider it hot or cold. Air temperatures affect our comfort, though our feelings are not an accurate measure of temperature. Twenty degrees below zero or -20° we consider very cold, 110° above zero we consider very hot. A room temperature of 65° to 70° we consider comfortable, though we shall learn later on that other things besides temperature affect our comfort in a marked degree. To indicate room temperature properly a thermometer should be placed on an inside wall not exposed to drafts of cold or warm air and not in an air pocket where there is little or no circulation. Sometimes thermometers are suspended by a cord in the center of a room about five feet above the floor. In this position they give a better reading of average room tempera- Heat Measurement 9 ture, but are inconvenient and troublesome for persons passing back and forth. Heat Measurement When the question is asked, "How is heat measured?" one naturally answers, "In degrees." This is not the case, as I CENTIGRADE 5CALE FAHRENHEIT Melting paint of common so/der 3b5 Soifinq point of woftr dtnormoi 'pressure 2oo Zl2 ° ,00 Aiorrnol temperature of human body 98.6' Txooms where occupants are riot etercnina so 68" frees/no paint of water 32" to ' o ■o to -xa* Freezing pomr of mercury — Jo TABLE OF USEFUL TEMPERATURES Mercury freezes Treezintj cold storage Water freezes I iDanaer of frost- Household refrigerator- Rooms vjhere occupants, are not exercising Gymnasium. Human body normoL Wafer boils ot normal pressure He/ting point of common Soft so/Je r A/eifi/fa point of lead. "enf- graJe -39 fvhren heif -38 ~/6 ±4. 13 20 Zl 13 31 too 185 321 ±12 Ji 39 +5 55 68 JO. 55 t8b 212 365 6ZI Fig. 1. Fahrenheit and Centigrade Scales. 10 A Short Course for Janitor-Engineers a little thought will show. Measuring heat in degrees would be like measuring water in inches. Three inches of water does not give us any definite idea of the quantity of water present, neither does the expression 60 degrees of heat give us any idea of the quantity of heat present. In order to have a definite idea of the amount of water indicated by three inches, we must know in what the water is contained. If the containing vessel is a small tin cup, we know that three inches of water is a small amount. If the vessel is a huge tank we know that three inches of water is a large amount. Just so with heat. Sixty degrees may represent a large or small quantity of heat, depending on what contains the heat. The standard substance in which to measure heat is water and engineers have decided to call the amount of heat necessary to raise one pound of water one degree Fahrenheit one heat unit or British Thermal Unit, usually abbreviated B. t. u. Two heat units would raise two pounds of water one degree or one pound two degrees. This B. t. u. is a very definite quantity applied to the measurement of heat, just as definite as the pint applied to the measurement of water. The re- lation between heat and temperature is also evident. To raise 40 pounds of water 10 degrees requires 40X10 = 400 B. t. u. It would require the same amount to raise 20 pounds 20 de- grees (20X20 = 400) or 10 pounds 40 degrees (10X40 = 400). In the same way 400 pints of water might fill a large tank to a depth of six inches, a smaller tank to a depth of 12 inches, and a still smaller one to a depth of 24 inches. The quantity of water, like the quantity of heat, remains the same in all cases. There is, however, an additional and very practical point to be noted about heat. Different substances require different quantities of heat to raise one pound one degree. We are all familiar with this fact, though we may not realize it. We say that certain substances heat up quickly or cool off quickfy, meaning that it requires only a small amount of heat to raise their temperature and that they give off but Specific Heat of Substance 1 1 little heat before they become cold. The number of heat units required to raise one pound of a substance one degree is called its specific heat. The specific heat of water is one because it requires one heat unit to raise the temperature of one pound one degree. The specific heat of cast iron is 0.129, meaning that it requires 0.129 heat units to raise a pound of cast iron one degree in temperature. The specific heat of lead is 0.031, hence, lead heats up very rapidly. The specific heat of brick work and masonry is about 0.20. The specific heat of air at atmospheric pressure is 0.238, that is, a pound of air heats up about four times as fast as a pound of water. This is one reason why a warm air system heats up so much more quickly than a hot water system and also the reason why it cools off more quickly, as everyone knows. Only two known substances heat up more slowly than water, that is, have a higher specific heat than water, hydrogen and bromine. As these are not substances with which we have to deal, we shall let them pass without further discussion. The following is a table of the specific heats of a few com- mon substances. Note that B. t. u. stands for British Ther- mal Unit. B. t. u. Water 1 Cast iron 0.129 Copper 0.095 Lead 0.031 Brick work 0.195 Masonry 0.215 Pine wood 0.467 Oak wood 0.570 Plaster 0.20 Air 0.237 From such a table as this we can see the reason why a building heated once a week, like a church for instance, re- 12 A Short Course for Janitor-Engineers quires so long to heat up. Not only the air, but the walls, radiators, seats and flooring must all be heated up. Cold radiators condense a large amount of steam, as every janitor knows. Let us suppose that a cast iron radiator weighing 500 pounds stands in a building where the temperature has dropped to 40°, how many heat units will it take to raise its temperature to 212°? 212° -40° =172° rise in temperature. To raise one pound of cast iron one degree requires 0.129 B. t. u.; to raise one pound 172 degrees requires 172X0.129 = 22.188 B. t. u. To raise 400 pounds 172 degrees requires 22.188X400 = 8875.2 B. t. u. This would be all the heat that could be ob- tained for heating purposes by burning one pound of average soft coal. You can easily see why cold radiators require the expenditure of a large amount of fuel to heat them up. The Effects of Heat All of us are more or less familiar with the effects of heat on different substances. The most common effect is expansion of the substance. Steam pipes expand and, if allowance is not made, such expansion results in warped and broken pipes and fittings. Brass expands more than iron or steel and for this reason brass bushings which are heated and cooled be- come loose. In allowing for expansion, it is safe to consider that a low pressure steam pipe will increase in length, when heated up to steam temperature, 1-64" for every foot. If one part of an object is heated so quickly that the heat does not have time to travel throughout the substance and produce an even temperature, we have unequal expansion, causing expansion stresses, which often are very severe. For this reason a boiler, especially a new boiler, should be fired up slowly, so that no portion may become overheated. For the same reason an engine is always gradually warmed up before starting. Frozen pipes are sometimes cracked by a blow Effects of Heat 13 torch if heated too quickly on the outside. Glass bottles, tumblers and water-gauge glasses are often cracked by too sudden heating or cooling in one spot. The remedy in all these cases is to heat or cool gradually. Water is peculiar. If it is heated from 32° to 39° it con- tracts slightly. If heated above 39° it expands. A cold boiler filled with water and heated shows a higher level in the gauge cocks and water-glass than before the fire was started, because of this expansion. Water heated above 39° tends to go to the top of the vessel in which it is contained because on ac- count of its expansion it becomes lighter, that is, weighs less per cubic foot. The fact that hot water rises is an important point to be remembered in piping all forms of hot water heat- ing appliances. In freezing, water expands nearly 1-10 of its volume and if closely confined bursts the containing vessel. Bursted pipes bear witness to this fact. Water which has been heated freezes quicker than fresh water, due to the fact that there is less air in it. This accounts for the statement often made, "Hot water pipes freeze quicker than cold water pipes." Air also expands and becomes lighter when heated. This causes the draft in a chimney, for the cold air rushes in and pushes the warmer, lighter air out. In a room the warmest layer of air is next the ceiling, the cold air is on the floor. These facts must always be borne in mind when ventilating a room by windows. Windows open at the top cool the room off rapidly and make it difficult to heat, for the warmed air rises and passes out as fast as it is heated. Questions 1. What are the two kinds of thermometers commonly used? 2. What are the freezing and the boiling points of water on each of these thermometers? 3. How is quantity of heat measured? 4. What do you mean by the specific heat of a substance? 5. Why does a hot water system heat up and cool off slowly? 14 A Short Course for Janitor-Engineers 6. Why does a warm air system heat up and cool off rapidly? 7. How would you prevent water pipes from freezing? Give at least two methods. 8. What do you consider to be the best method of thawing frozen pipes if they are accessible? 9. At what temperature would you keep a manual training shop in which boys are working? 10. At what temperature would you keep the halls of a school building? 11. Suppose a boiler to be hot and the water low, what is the effect of rapid filling under these conditions? 12. Explain two methods of providing for expansion in a short run of pipe? 13. How is the expansion of water provided for in a hot water system? 15. A teacher sitting on the platform at one end of the room says the room is too warm. The thermometer in the main room shows 68°. What is one good reason for this condition? II HOW HEAT TRAVELS Heat travels from one part of a substance to another or from one object to another, as you know if you heat a poker in fire, warm your feet at the register or burn your finger on the stove. The important point to be noted is that heat al- ways travels or flows from a higher temperature to a lower temperature just as water flows from a higher level to a lower level. Heat never flows from a low temperature to a high temperature. In other words, a room cannot be heated if the stove or radiators in it are no warmer than the room. The hotter they are, the faster the heat flows from them to the room. Always bear in mind that there is no such thing as "cold" and that "cold" does not travel. Heat travels, cold does not. In a thermos bottle filled with ice cream the cold does not come out. The heat goes in (slowly) from the outside and thaws the ice cream. If the same bottle is full of hot tea the heat travels out and the tea cools off. The purpose of the vacuum jacket or insulating material is to keep the heat from traveling out or in, according to whether the high temperature is inside or outside. We put building paper on our walls, use double windows, and cover our steam pipes, not to keep cold out, but to keep the heat in. We may put weatherstrips or metal strips around windows and doors and stop up cracks to prevent cold air coming in. These do not, however, keep the "cold" out. They do help to keep the warm air in for whether the air comes in or goes out of a window or crack depends upon whether the air pressure is greater out- side or inside the building and not upon the difference in temperature. There are three methods of heat travel or heat trans- mission, as it is usually called, with which we are familiar and which we recognize as soon as pointed out. These three methods of heat travel are : 15 16 A Short Course for Janitor-Engineers 1. Conduction. 2. Convection. 3. Radiation. Heat is conducted from the hot part of a substance to a colder part of the same substance or to another colder sub- stance. Every fireman knows that when he runs one end of the slice bar or poker into the fire the other end gets hot. Heat is conducted from one end of the bar to the other. In a boiler the heat is conducted from the outside or fire side of the shell through the iron to the water on the inside. Heat is con- ducted from the inside of a radiator to the outside. Other examples of conduction will suggest themselves. Note that when heat travels by this method the particles of the substance do not move perceptibly. Heat may be carried from one part of substance to another by the actual movement of the particles. This method of heat travel is known as convection or carrying. Naturally heat does not travel by this method in solid substances like iron, copper or lead, because the particles cannot move. Beat travels by convection or canying in liquids, like water, or gases, like air. The air of a furnace is heated in the base- ment and actually carries the heat to the floors above. We say the air "circulates." If it does not circulate the heat cannot be carried, the room does not warm up and the furnace fails. Heat is carried in the same way by the hot water in a hot water system or by the steam in a steam system. In each case the steam or water carries its load of heat to the radiators and "dumps it" so to speak, and returns to the boiler for another load. If there is no circulation there is no heating. A boiler which has poor circulation will not steam well. The third method by which heat travels is radiation. By this method heat is shot out in straight lines from the surface of hot objects and strikes and heats other objects. Heat is radiated or shot out from the side of a hot stove or How Heat Travels 17 radiator and we feel the burning sensation on our hands and faces. As you walk by a red hot stove or open fire you put up your hand or cap to shield yourself from the heat shot out or radiated from it. Heat which is radiated does not heat the air effectively through which it passes. This is why an open fire may scorch one's face and yet one's legs and body feel uncomfortably cold. The air of the room is not being heated well because the heat is radiated or shot through it directly to the objects in the room. Heat is radiated from the sun. Stones, bricks and metal placed in the sun become hotter than the surrounding air. In the ordinary steam radiator the three methods of heat transmission are illustrated. The heat is brought into the radiator by the steam by the method of convection. It is conveyed from the inside of the radiator, to the outside by conduction and is delivered to the room partly by convection (circulation of air) and partly by radia- tion. See Fig. 2. Circumstances Affecting Heat Travel Substances vary greatly in their ability to conduct heat. In general it may be said that solids, especially metals, are good conductors of heat, liquids are not so good and gases are the poorest conductors of heat. Some solids are not good conductors of heat. Such substances as magnesia block, asbestos cement, hair felt, cork and wood are used for pipe coverings so as to keep the heat in. The thicker the substance is, the harder it will be for the heat to get through it. For this reason a boiler shell cannot be made too thick or the heat will not be transmitted easily to the water. Glass is not a good conductor of heat, but nevertheless heat will be trans- mitted through a single window about four times as fast as through a wall, because the glass is so thin. This partially accounts for the fact that rooms having a large number of windows are hard to heat. Dead air space is a very poor con- ductor of heat, hence an air space between two walls in a Air currents carrying heat -connection Radioted heat -radiation Heat conducted through iron fo outer surface - Conduction. HOW A RADIATOR HEATS 5zi Window open at top How heat may be wasted oy connect/on currents r,g 3 COWECTlON CURRCNT5 AIDING /A/ HEATING F/Q 4 "Empty buckets refi/rn/na (water) LATENT HEAT CARRIED Br STE/4M rig 5 18 Heat Conductors and Non-Conductors 19 building or between two double windows aids in keeping heat in. For the same reason a dead air space in a radiator pre- vents its heating and we say the radiator is "air bound." The air will not let the hot steam enter the radiator and will not conduct the heat from the steam through the radiator. Soot and scale are very poor conductors of heat, hence every effort should be made to keep them off boiler surfaces. One- sixteenth inch of scale or soot is said to diminish the con- ducting power of a boiler tube 25%. For the same reason the pipe coverings should be kept in good condition, so as to prevent the escape of heat. In one case we remove the covering so as to allow free passage for the heat; in the other we keep the covering in good shape in order to obstruct the passage of heat. Fireless cookers are built solely for the purpose of keeping heat in. Radiation takes place from the surface of a substance and the condition of the surface as well as the material affects its radiating power. In general, highly polished, light colored surfaces will not radiate heat so well as dull, dark colored surfaces. Stoves and steam pipes should be black if they are intended to give out heat, but hot air pipes, cooking utensils should be brightly polished in order to lose as little heat as possible. A nickel plated stove will be about half as effective as a black stove of the same temperature. Bright tin warm air furnace pipes often lose less heat bare than they do when covered with one or two layers of asbestos paper, since the paper radiates the heat so much more than the tin as to more than balance the effect of the thin asbestos covering. The insulating covering should be f " thick or more to save heat on a bright tin pipe. A simple experiment shows the difference between the heat radiated from a black surface and a polished surface very clearly. Take a new tin shingle and smoke one side over an open kerosene flame until it is black. Leave the other side clean. Heat the shingle on a stove or clean flame. Have some one hold the shingle between your open palms 20 A Short Course for Janitor-Engineers about an inch from each. The difference in the heat radiated from the two surfaces is very noticeable. Another point to be noted is that the rate at which heat is transmitted depends on the difference in temperature, just as the rate at which water flows depends on the difference in level. If, on a mild day in winter, the temperature is 50° outdoors and 70° inside the building, the difference is 20° and the heat will pass out through walls and windows at a certain rate. If, on the next day, the outdoor temperature goes down to 30°, the difference is 40° and the heat will pass out approximately twice as fast. We say approximately, because we know that the rate of heat transmission increases faster than the difference in temperature. Some engineers state that it requires 25% more fuel to keep a building at 70° than it does to keep it at 60° in cold winter weather. Hence, to save fuel, rooms should be kept at as low a temperature as possible consistent with health and comfort. Latent and Sensible Heat So far in discussing heat we have assumed that it always raises the temperature of substances. This is not always the case. Heat may change the state of a substance. It may change ice to water, melt the ice, or it may change water to steam, evaporate the water. When heat is changing the state of substance, it does not raise its temperature. To prove this, place a mixture of ice and water in a cup and take its temperature. The thermometer will show 32°, the freezing point of water or melting point of ice. Place the cup on the stove and stir the mixture continually. The temperature will remain at 32° until the ice is all melted. The reason is that the heat is all used in melting the ice. It cannot raise the tempera- ture until the melting is all done. It requires 142 heat units to melt a pound of ice. This heat is known as the latent heat of fusion or melting. To continue this experiment after the ice is melted heat the water until it boils at approximately 212°. Latent and Sensible Heat 21 Here, again, the thermometer stops rising and the water changes to steam. The heat going into the boiling water is all used in evaporating the water and cannot raise the tem- perature as long as the water is in an open cup. This heat is called the latent heat of evaporation. It takes 970.4 B. t. u. to evaporate one pound of water at atmospheric pressure. This latent heat is all given up by the steam when it condenses back to water and this heat is what is used in a steam heating system. If water is in a boiler under pressure it can be heated hotter than 212°. Every pressure has a certain fixed tempera- ture which never varies. The pressure, temperature and latent heat of steam are all given in what are called steam tables. These are very important for the stationary engineer to understand and they should be understood, at least in part, by the man who runs a heating system. The following is part of a steam table showing the properties of steam from one to five pounds pressure, which would be within the limits of most heating systems. Temperature Latent Heat ressure lbs. Degrees B. t. u. per lb 212° 970.4 1 215 968.23 2 219 966.2 3 221 964.27 4 224 962.4 5 227 960.6 Note carefully that as the pressure increases the tempera- ture of water and steam increases. High pressure steam is hotter than low pressure steam. The column headed "Latent Heat, B. t. u. per pound" tells just how many heat units are given to the radiator when one pound of steam is con- densed at that pressure. For instance, if one pound of steam at or atmospheric pressure is condensed as in a vapor system, 970.4 B. t. u. are given to the radiator to be carried into the 22 A Short Course for Janitor-Engineers room. Now note that if steam at three pounds pressure is condensed only 964.27 B. t. u. are given up. High pressure steam does not have so many heat units to give up for heating as the low pressure steam. This is one advantage of low pressure steam for heating purposes. High pressure steam will heat faster, but more pounds must be circulated to carry the same number of heat units to the room. The important point to remember is that steam must be condensed in order to get the heat out of it. Heating with steam might be com- pared to carrying water in buckets on an endless chain. Every pound of steam circulated represents one bucket. Condensing a pound of steam is the same as dumping a bucket. High pressure steam would be represented by small buckets running at a rapid rate. Low pressure steam would be repre- sented by larger buckets running at a slower rate. See Fig. 5. In an ordinary steam heating system one square foot of direct radiation will condense about one-fourth of a pound of steam per hour. This means that each square foot of radia- tion is capable of supplying about 240 B. t. u. every hour to the room. Questions 1. Explain why a room in which there is no circulation will not heat. If you found a room difficult to heat on account of air pockets and dead air spaces, what would you do? 2. Why are rooms with high ceilings difficult to heat? 3. A display window in a large building was continually covered with frost in cold winter weather. The owner was advised to use an electric fan. Explain how this would prevent frost from gathering. 4. A building is heated by steam sent directly through the coils without returning to the boiler. Engineer A says he can heat the building faster by blowing steam through rapidly so that live steam flows from the outlet. Engineer B says he can heat faster by allowing the steam to con- dense. Which is right? Which is more economical? 5. Some persons recommend putting a tub of water in the cellar to prevent the freezing of vegetables. Is there any good reason for this? Explain. Questions on Heat 23 6. The pupils in a certain building heated by stoves complain of the heat when seated near the stove. Suggest a remedy for this condition. Draw a rough sketch of your idea. 7. Will a building which is cold in winter be cool in summer as a general rule? Why? 8. A large smoke pipe passes through a certain room. It is desired to utilize the heat from this pipe to warm the room. Should the pipe be bright, galvanized iron or painted black, and why? 9. Why do aluminum utensils heat up so quickly and uniformly? What is the reason for putting a wooden handle on a poker? 10. When the temperature is the same on both sides of a building, why is the side toward the wind harder to heat? 11. Engineer A says, "Never open a window over a radiator, it cools the radiator off." Engineer B says "Always open a window over a radiator if you can." Which is right? 12. Explain the precautions you would take in putting on double windows in order to secure the best results. 13. Do the metal shields sometimes placed behind steam radiators increase or decrease the heat given off and why? Ill COAL AND COMBUSTION The heat supplied to a building is usually obtained by burning coal and therefore every janitor, or at least every fireman, should know something about the composition and properties of coal. Coal, as we shall consider it, is made up of four different substances : 1. Carbon, 2. Gas, 3. Water, 4. Ashes. Of these substances, the carbon and most of the gas are combustible; that is, they will burn; the water and ashes will not burn. Carbon is the solid combustible matter in the coal, the burning of which produces most of the heat. Coke, charcoal and graphite are other common forms of carbon. The gas found in coal is chiefly in the form of compounds of hydrogen and carbon, called for short hydro-carbons. These hydro-carbons burn with a very hot flame and hence are a valuable part of the fuel. Water and ashes are found in all coals in varying quantities. In addition to the substances mentioned some coals contain sulphur. Sulphur will burn, but does not produce much heat and is an undesirable element in coal, due to the fact that, when burned, the gas formed mixes with the moisture from the coal or steam from the ash pit and forms an acid which corrodes the grate bars. To determine the characteristics of any kind of coal it is necessary to find out in what proportions the substances contained are present. To do this a chemical analysis is made. The one most useful to engineers is known as the proximate (approximate) analysis. This tells simply how much carbon, gas, water, ashes and sulphur are in the coal. The chemical terms used are the following : 24 Characteristics of Coal 25 r 3&5Z, 50 F T COAL. A ILLINO IS fig ff Pennsy I von 1 a hard cool \6as{\ COMPOSITION OF TYPICAL COALS. Carbon — Fixed carbon. Gas — Volatile matter. Water — Moisture. Sulphur — Sulphur. The "fixed carbon" is called " fixed" to distinguish it from the carbon combined with the hydrogen in the gaseous hydro-carbons, which pass off when the coal is heated. Coke is coal from which all gas and moisture have been driven off by heat and consists of fixed carbon and ash. We are accumstomed to divide coal into two classes, hard and soft. Speaking more scientifically, we may say that there are three general classes of coal: Anthracite, or hard; semi-bituminous, or moderately soft, and bituminous, or soft 26 A Short Course for Janitor-Engineers coal. The difference between them is in the amount of volatile matter contained. Hard coal contains very little volatile matter, semi-bituminous contains more and common bi- tuminous or soft coal contains a large proportion. The aver- age proportions of different substances in coals of the different classes are shown in Fig. 6. The amount of volatile matter contained in a coal is a very good indication of its smoke producing properties. Coals containing much volatile matter are hard to burn without smoke. "Smokeless" soft coals are simply soft coals contain- ing a small amount of volatile matter. Bituminous Coal Bituminous coals are subdivided into caking and non- caking coals. Caking coals are those which melt and run together when thrown on the fire, thus forming a blanket or cover over the fuel bed on which blisters or puff balls of gas form. These burst and allow the gas to escape and burn with a bright yellow or reddish flame. These coals usually contain a large amount of gas and for that reason are valuable for gas making. Non-caking coals do not melt and run to- gether when heated and are sometimes called "free burning" coals for this reason. They make good fuel for heating and power plants. They may be distinguished by the fact that they break in layers and the broken surface at right angles to the layers appears bright and shiny. Semi-bituminous coals, mined chiefly in the East, make a very hot fire and but little smoke. Pocahontas is a good example of this type of coal. Hard coal is too well known to need further description. To show what his coal is made of, a dealer furnishes an "analysis," that is, a table showing what the coal contains. The easiest way to get a clear idea of the meaning of these percentages is to consider that the columns headed moisture, volatile, fixed carbon and ash represent the number Coal Analysis 27 PROXIMATE ANALYSIS OF REPRESENTATIVE COALS Fixed Heating Moisture Volatile Carbon Ash Sulphur Value % % % % % % 1. Hard 5.41 7.03 71.79 15.78 .743 12047 2. Semi-bituminous. . 1 .63 17.17 75.34 5.86 .75 14672 3. Bituminous 12.39 36.89 [41.80 8.92 3.92 11399 4. Bituminous 14.21 33.17 37.40 15.22 4.66 10019 5. Bituminous 7.91 37.94 45.02 9.13 3.62 12200 of pounds of the substance in 100 pounds of coal. That is, in 100 pounds of coal No. 1 there are 5.41 pounds of water, 7.02 pounds of gas, 71.79 pounds of fixed carbon, and 15.78 pounds of ashes. These, added together, make 100 pounds. In this 100-pound lump of coal is 0.743 of a pound of sulphur. Sulphur is usually taken out separately and is said to be "separately determined." Glancing at coal No. 1 you will note that about one-fifth of it is water and ashes. At $8.00 per ton one would pay $1.60 for water and ashes. Conclusions from Analysis In drawing our conclusions from a coal analysis, we may say that a high percentage of volatile matter indicates that the coal must be carefully fired in order to get good efficiency and avoid making smoke. Coals low in volatile matter do not require such careful firing. Coals high in ash increase the work of ash removal and of course do not contain so much combus- tible matter. Coals containing a high percentage of moisture cause loss of heat because the heat required to evaporate the moisture in the furnace cannot be given to the boiler. There may, however, be reasons for wetting the coal as we shall see later on. Sulphur, as has been said, is an undesirable element. The last item, "the heating value," is an important one. Heating value means the number of B. t. u. developed by burning completely one pound of coal. For instance, the 28 A Shwt Course for Janitor-Engineers heating value of sample No. 3 above is 11,399 B. t. u. This means that one pound of this coal completely burned would develop 11,399 B. t. u. Referring to the definition of B. t. u. this means that the heat is sufficient to raise 11399 pounds of water 1°, or 1 pound of water 11399°. A boiler and furnace cannot make use of all the heat units in the coal, for some are lost up the stack, some are radiated from boiler front, pipes and setting out into the boiler room, and some are lost in un- burned fuel in the ashes. In fact, if the average boiler makes use of 60% to 65% of the heat units in the coal it is doing well. The duty of the fireman is to see that as large a proportion of the heat as possible is utilized, since the per cent of the total heat in the coal present in the steam delivered to the heating system is a measure of the efficiency of the boiler and furnace. In buying coal we are interested solely in buying heat which we can use. The coal which furnishes the greatest number of heat units for one cent is the cheapest coal to buy, provided it can be burned efficiently. Some furnaces are not adapted to burning cheap grades of coal and therefore waste a large amount of heat. In this case it is cheaper to buy a better grade of coal and use a larger percentage of the heat. For instance, suppose that coal No. 2 above cost $5.75 per ton of 2,000 pounds. The number of B. t. u. purchased for one cent is 14672X2Q0 ° = 51034. Taking coal No. 5 at $4.50 575 per ton to compare with it, the number of heat units for one L . 12200X2000 c , OQO T , , ,, . ., , , , cent is =54333. If both coals could be burned 450 equally well in the furnace, coal No. 5 would furnish more heat for the money. If, however, due to the construction of the furnace and draft conditions, only 60% of the heat units in coal No. 5 could be used, while 65% of the heat units in coal No. 2 were available, conditions would be reversed. Coal Sizes and Names 29 51034 X .65 = 33172 B. t. u. actually used for every cent expended in the case of coal No. 2. 54333 X. 60 = 32599 B. t. u. actually used for every cent expended in the case of coal No. 5. Hence, in this case the high priced coal would actually be cheaper to use, due to the greater efficiency in burning it. This shows that the question of selecting proper coal is a complicated one and that actual boiler tests are necessary in order to determine the best coal for a certain plant. Names and Sizes of Coal Western soft coals are classified and known by the fol- lowing names: (1) Run-of-mine; the unscreened coal taken from the mine. (2) Lump coal; divided into 6-in., 3-in. and lj-in. lump, according to the diameter of the circular openings over which the grades will pass. Sometimes sizes are given as 6x3-in. or 3xl|-in., meaning that the coal will go through the opening designated by the first figure and over the one desig- nated by the second. (3) Nut coal; divided into 3-in. "steam nut," lj-in. "nut" and f-in. "nut." (4) Slack coal; coal that passes through a f-in. opening. (5) Washed sizes; numbered 1, 2, 3, 4, 5, from the 3-in. size down. The common sizes of hard coal are: 1, buckwheat; 2, pea; 3, chestnut or nut; 4, stove or range; 5, egg. Coke is sized as follows: 1, pea f in. to \ in.; 2, nut f in. to \\ in.; 3, small stove \\ in. to 2 in.; 4, large stove 2 in. to 2\ in. ; 5, egg 2\ in. to 3 in. In calculating sizes of bins for storing coal and coke we may take 40 cu. ft. of bituminous coal to one ton of 2,000 pounds and 71 cu. ft. of coke to one ton. One ton of hard coal occupies approximately 37 \ cu. ft. Some soft coals when 30 A Short Course for Janitor-Engineers stored in quantities in a bin or pile heat and take fire. Coals which break into fine dust are more apt to heat than those which do not. The following are some precautions to take when storing coal in order to avoid heating. (1) Store in small piles so that no part of the coal is more than 8 ft. from an air cooled surface. (2) Eliminate dust and fine coal so far as possible. (3) Store the coal dry. (4) Store so far as possible from external sources of heat, such as boilers and furnaces and hot cinder heaps. (5) Pile the coal evenly, not in a conical pile, and do not allow the dust to accumulate in the center with all the lumps around the edges. (6) Use the older parts of the storage first and do not allow old coal to accumulate in the corners and be covered by fresh coal. Combustion Knowing something about what coal is made of, we are now ready to take up the problem of burning coal. Combustion or burning is a chemical action accompa- nied by light and heat. The chemical action seen in burning coal is caused by the oxygen of the air uniting with the combustible substances in the coal. Air is not all oxygen, but approximately 1-5 oxygen and 4-5 nitrogen. The oxygen is the active agent in causing combustion; nitrogen simply accompanies the oxygen through the furnace unchanged and has no effect except to dilute the oxygen. Nothing is destroyed when coal burns. It is true that the coal disappears as coal. Different substances are formed and pass off as gas or remain in the ashes, and in this changing process heat is developed. This, to the fireman or engineer, is the important result. He is interested in the dif- ferent substances formed only as they indicate whether all the heat possible has been developed from the coal. Conditions Needed for Combustion 31 In order to have combustion three conditions must be fulfilled, which may be called the three "enoughs." 1. There must be fuel enough. 2. There must be air enough. 3. There must be heat enough. A man who pays attention to the first condition only is a coal passer, not a fireman. A fireman knows that the second and third conditions are as important as the first for efficient combustion. The necessity for fulfilling all three conditions is well illustrated by the ordinary kerosene lamp. See Fig. 7. Heat Air V^ A/o Fue/ A/o Air A/o Heat J Fue/ Three conditions for combustion A/O COM BUS TlON Fig. 7 If there is no oil the lamp goes out. If a tight cover is placed over the top of the chimney or the holes in the bottom of the burner stopped up, the lamp goes out for lack of air. The lamp cannot be lighted without a match, flame or some other source of heat. This is because the fuel must be made hot enough to burn. The temperature at which a fuel begins to burn is known as its "ignition point." We put the lamp out by blowing upon it to cool the wick and the fuel below the ig- nition point. These same three conditions must be fulfilled in a boiler furnace, as you will see if you think it over. The third condition is the one to be fulfilled when starting the 32 A Short Course for Janitor-Engineers fire and the first and second concern the handling of the drafts and the coal scoop. The ignition point of carbon or the solid coal is about 750° F. and of most of the gases in coal about 1100°. If cooled below these temperatures these substances will not burn. A furnace is not so easy to handle as a lamp and therefore efficient combustion is more difficult to secure. To make this clear, table No. 2 has been made out showing just what happens when coal burns. Note carefully that every pound of a combustible substance requires a definite, fixed amount of oxygen to burn it, which means a definite, fixed amount of air. A pound of carbon will burn with two definite amounts of oxygen or air, but will not burn with any more or any less than these fixed amounts. The following table states just how many pounds of air are required to burn completely a pound of the various substances in coal and what substance is formed. Table 2. Requires to burn A nd forms when One pound of completely burned Carbon 12 lbs. of air Carbon dioxide *Hydro-carbon 17 lbs. of air Carbon dioxide and water Sulphur 4 lbs. of air Sulphur dioxide Twelve pounds of air are approximately 150 cubic feet or the amount of air contained in a box 5' 4"x5' 4"x5' 4". Carbon dioxide is a colorless, odorless, suffocating gas found in the air, breathed out from our lungs, and also in the charged water obtained at soda fountains. It sometimes rises from the stomach into the nose after drinking a glass of soda water and causes a choking sensation. Sulphur dioxide is a gas with a very pungent odor. A sulphur candle, when * There are several hydro-carbons requiring different amounts of air. This is an average. Heat and Combustion 33 burned, produces it in large quantities and it can also be de- tected whenever a sulphur match is lighted. Each pound of a substance when burned develops a certain amount of heat, as the following table shows. A pound of carbon will burn incompletely with just half enough air, that is, with six pounds instead of twelve, but in so doing does not give nearly so much heat. Hence, the necessity for com- plete combustion. Table 3. One pound of In burning develops Carbon (completely burned) 14500 B. t. u. Carbon (half burned) 4400 B. t. u. *Hydro-carbons 23500 B. t. u. Sulphur 4000 B. t. u. Every pound of coal contains these different substances and they must all be burned if all the heat is to be obtained. Carbon and sulphur which are solids and cannot get away are easy to burn if enough air is supplied. The hydro-carbons in the form of gas have a high ignition temperature and are likely to fly off up the chimney unburned in the smoke unless special care is taken. To make sure that there is air enough, more air than is theoretically necessary must be admitted to the furnace. Instead of twelve pounds of air per pound of coal, from eighteen to 24 pounds are usually used. These six to twelve pounds above what is theoretically necessary are known as "excess air." If too much air is allowed to enter the furnace it carries heat off up the stack and wastes it. The proper adjustment of the air is one of the fine points of good firing. Let us see now just what happens when coal is thrown into a furnace. As soon as the fresh coal strikes the hot fuel bed the latter is cooled down. The air coming in through the open furnace door also helps to lower the furnace tempera- ture. As the fresh coal heats up the gas begins to pass off, 34 A Short Course for Janitor-Engineers starting at a temperature of about 220°, and coming off faster and faster as the coal heats up. This gas must be burned at once or not at all, for it is rushing off up the stack. To burn it, there must be air enough and the furnace must be hot enough. If the furnace has been cooled down too much by a heavy charge, the gas escapes unburned because it is not hot enough. If drafts are closed or not enough air can come through the fuel bed, the gas escapes unburned for lack of air. In either case, the dense black smoke is a signal that com- bustible gases are escaping and causing loss. It is easy to see that firing and handling a furnace require skill as well as muscle. Fuel and drafts must be handled together in order to secure the best results. Methods of firing which are simply the practical application of the principles of com- bustion will be taken up in the next chapter. Questions 1. Mention the important things you would consider in selecting a coal from analyses furnished by the dealer. 2. Under what conditions would you advise burning hard coal? 3. What are the three conditions necessary for combustion? How much air is necessary to burn a pound of coal? ' 4. Why is it desirable to admit more air to the furnace than is theoretically necessary to burn the coal? What is the effect of too much air? 5. A coal contains 12622 B. t. u. per lb. A furnace and boiler make use of 63% of the heat units. How many units are available in the steam per lb. of coal? 6. A floor space 15x20 feet is available for the storage of coal. Cal- culate dimensions of a bin to be placed on this floor large enough to hold 40 tons. 7. What is run-of-mine coal? What is lump coal? What is slack? What is steam coal? 8. An engineer says his coal pile always starts to heat right under the hole where the coal is shoveled in. What is the reason for this and what would you do to prevent it? 9. Does sulphur in coal have any harmful effect and if so, what is it? 10. State briefly the differences between hard coal, soft coal, and coke, and the circumstances under which you would recommend their use as fuel. IV METHODS OF FIRING In the preceding chapter the principles of combustion were stated and explained. Proper firing is simply in accord- ance with these principles for the purpose of accomplishing two things: First, the elimination of smoke; second, greater economy in the use of coal. Elimination of smoke often means and usually does mean greater economy, but this is not al- ways the case. Smoke Prevention We sometimes hear the expression, "smoke consumption." There is no such thing as smoke consumption and the term should never be used. Perfect combustion means smoke pre- vention and to prevent smoke the fire should be managed so that combustion will be as complete and perfect as possible. The kerosene lamp used as an illustration will be useful here in showing the causes of smoke. Figs. 8a and 8b show two common ways of making a furnace or a lamp smoke. In Fig. 8a the lamp smokes because it is turned too high. There is too much fuel for the air supply, therefore some of it gets away unconsumed in the form of gas and lampblack or soot. This represents the conditions in a furnace into which a very heavy charge of fuel has been thrown. The furnace conditions are really worse than those represented in the lamp because of the cooling effect of the fresh fuel. This does not occur in the lamp to any great extent. Fig. 8b represents the condition in a furnace when all drafts are closed with a heavy charge of fuel on the grates. The remedy in each case is to lessen the quantity of fuel or increase the air supply. The air supply of a lamp may be increased by increasing the height of the chimney. This may be done (for illustrative purposes) by inserting a pasteboard mailing tube or roll of paper in the chimney top. This will increase the draft and the lamp may 35 36 Causes of Smoke 37 be turned considerably higher without smoking. When the tube is removed the lamp at once begins to smoke again. Very short stacks and poor draft are often a cause of objectionable smoke. Over these conditions the fireman naturally has no control, unless the poor draft comes from leaky or clogged smoke passages. Fig. 8c shows a smoking lamp without a chimney. This smoke is due to the fact that the air, although it surrounds the wick and flame, does not have a chance to thoroughly mix with the fuel. For this reason particles of fuel escape unburned. When the chim- ney is in position, the air coming in through the holes under- neath mixes thoroughly with the fuel and burns it. This question of proper mixing of air and fuel is an important one in furnace construction. Fig. 8d shows another common method of producing smoke. A nail, or glass, or metal rod is held in the flame, cooling it down below the burning temperature. Smoke is immediately formed when combustion ceases or is hindered. This is what happens in a boiler with a small firebox in which the flames come in contact with the boiler tubes and shell before combustion is complete. The blazing gases are cooled off just as is the lamp flame, combustion ceases and a black cloud of smoke is the result. Soft coals containing a large amount of gas need a large combustion space so that com- bustion will be complete before the flaming gases strike the cold boiler surfaces. Fire brick arches are also used, which, by becoming white hot, aid in keeping the temperature up. To sum up the entire question of smoke prevention, it may be said that any fuel can be burned without objectionable smoke, provided it is mixed with the proper amount of air at the proper temperature. This, like many other things, is easier said than done. 38 Three Firing Methods 39 Methods of Firing In a properly designed power plant using mechanical stokers, the prevention of smoke is easier than in the small hand-fired plant. Every fireman, however, should do his best to fire his furnace economically and with as little smoke as possible. It should be a matter of pride to say that black smoke seldom issues from the stack. In many settings smoke cannot be entirely prevented, due to faulty design, but much can be done toward lessening the smoke by proper methods of firing. There are in use three general methods: 1. Spreading method. 2. Alternate method. 3. Coking method. When firing by the spreading method, the fireman spreads the coal as evenly as possible over the entire surface of the fuel bed. This is a common and satisfactory method for firing hard coal. It is not a satisfactory method for firing soft coal unless very small amounts are fired at one time. If the fresh coal in large quantities is spread evenly over the entire fuel bed, the temperature of the furnace is lowered considerably. The gases at once begin to pass off from the coal, due to the heat of the fuel bed below. As the furnace temperature is low over its entire surface the gases fail to ignite and pass off up the chimney unburned. The covering of the entire fuel bed also prevents the free passage of air through it at the very time when the greatest amount of air is necessary to mix with and burn the gases. See Figs. 10 and 11. Letting air in over the fire aids somewhat, but this cannot produce complete com- bustion if the temperature is too low. Hard coal can be fired successfully by the spreading method with little smoke because there is so little gas in it and it distills off so slowly that the incoming air can mix with and burn it satisfactorily. In firing by the alternate method the fireman spreads coal on one side of the furnace, leaving the other side as a 40 A Short Course for Janitor-Engineers bed of fresh red coal, through which the air can pass freely. After the side just fired has become well ignited and red, a charge is fired on the other side. This process is continued and at no time is the entire fuel bed covered with fresh coal. The reason for this method is easy to see. The gases distilled off from the fresh charge are mixed with the hot air coming through the red coals on the other side and thus are consumed. The temperature of the furnace also is not lowered so much as it would be by covering the fuel bed entirely. See Fig. 13. A janitor very often says that, due to duties other than firing, he must be absent from the fire room often for quite a length of time. For this reason he must fire large charges and cannot give the fire the attention required by the alternate method. For this reason the third method, the coking method, is best adapted for firing furnaces in school buildings where the janitor cannot give undivided attention to the furnace. In firing by the coking method the coal is fired in quite a large charge right in front of the dead plates and allowed to coke or free itself of gas. The gas passing off must go back over the red hot fuel bed before it can get out of the furnace, and in so doing is burned. After the gas has distilled, the charge is shoved back bodily to the rear of the furnace, making the front of the fuel bed slightly lower than the rear and a fresh charge is again fired in front. This method is sometimes combined with the alternate method with good results in large furnaces. A janitor firing by this method can fire comparatively large charges with fair economy and a minimum of smoke. To produce the least smoke and best economy the coal should be fired in very small charges and by the alternate or spreading method. Fig. 12 shows the ap- pearance of a furnace fired by the coking method. Be care- ful that bare spots and holes do not form at the rear of the grate. Essentials of Good Fire 41 Keeping a Good Fire A good fire in a furnace is light, bright and level. See Fig. 17. A light fire means a thin fire. A soft coal fuel bed should be from 4" to 10" thick for the best results, the heavier fires naturally are necessary in cold weather. The reason for a thin fire is to allow free passage of the air through the fuel bed and a proper mingling with the fuel. A thick fuel bed, like a blanket, prevents the passage of air unless the draft is very strong. A thin fire properly cared for makes steam easier and with less coal than a fire which is too thick. A bright fire means one which is red all through. A dull fire is clogged with clinkers and ash and cannot burn well. See Fig. 15. A thick fire is often a dull fire. A level fire is one which is the same thickness over the entire grate. If there are holes in the fire or bare spots on the grate the air rushes through them in much larger quantities than is necessary for combustion and carries heat off up the chimney and wastes it. Fig. 14 shows the effect of holes in the fire. Bare spots are very likely to occur at the rear or sides of the grate. In filling up large holes do not use fresh coal, level the surface of the bed and fill the holes with red coals before firing a fresh charge. Remember that thick spots are points where the coal for some reason does not burn and should therefore be leveled off. It is often possible to prevent the formation of holes by firing the coal carefully each time, so as to fill up the thin places. By so doing the necessity of raking over the hot coals and stirring the fire is avoided. Special Methods and Appliances Hard coal needs a strong draft under it and no air over the fire. Soft coal, due to the combustible gases, needs a draft over the fire. Simply to let in air over the fire is not always enough. To be effective this air must be thoroughly mixed with the gases. When unobstructed the air and gases tend 42 Control of Draft 43 to flow in parallel streams rather than to mix, as shown in Fig. 9c. Fire brick piers in the combustion space, on the bridge wall or beyond it, and wing walls and deflection arches are often installed to force the mixing of these streams of air and gas. Steam is sometimes forced in over the fire in a small, thin stream. This breaks up the currents of air and gas and causes better mixing. These steam jets as they are called are most effective when air is admitted around them instead of altogether through the firing door. In this way the steam jet acts as an air injector as well as a mixer. The velocity of the steam, not its quantity, is what counts. Air, not steam, supports combustion. If no steam jets are available, air should be admitted over the fire through the dampers in the firing door for a short time, say two to five minutes, after firing a fresh charge. Sometimes it is a good plan even to leave the firing door slightly open for a short time. To leave either door or drafts open after the gases have passed off wastes fuel by cooling the furnace and sending hot air up the stack. To control the draft under the grates use the stack damper rather than the ash pit doors. One reason is because it shuts off the draft through all openings, ash pit doors, leaks and firing doors and another reason is because it allows the cool air to circulate freely under the grates, thus preventing overheating and warping of the grate bars and the clinkering of the coal. To regulate the draft properly, the stack damper should be within easy reach or have a chain attached. See Fig. 18. There should also be in every fire-room a draft gauge, in such a position that it can be seen and the damper operated from the same spot. Fig. 18 shows a common form of draft gauge. It is simply a "U" shaped glass tube, f" or 5-16" diameter, filled with water attached to a graduated scale. Sixteenths of an inch are fine enough. The gauge is connected with the combustion chamber by a piece of \" iron pipe and a piece of rubber tubing. The draft gauge 44 A Short Course for Janitor-Engineers damper shoft Tf - 1- weight f/re door ( \£drafr gouge Draft Gauge .Show- ing i Draft Fi&ib Draft Gouge and Damper Connection shows the difference between the pressure of the gases in the setting and the air outside measured by the difference in height of the liquid in the two columns of the gauge. This difference is expressed in inches of water and we say the draft is \" of water or §" of water. After you have become familiar with the gauge you can tell what is happening in the furnace by looking at the gauge. If the draft over the fire is low when the damper is open wide, it means holes in the fire. If the draft is very high it means dense clinker or ashes on the grates. The average draft in the breeching in plants with 100 to 150 foot stacks is f" of water. The draft over the fire varies from V tor or more. Preventing Clinkers 45 Clinkers Every fireman dreads clinkers, and for good reasons, and seeks to prevent them. As in other cases, to find the remedy we must know the cause. Clinker is simply melted ash, hence, if we can keep the ash from melting in the furnace, we can prevent clinker. The temperature at which ash will melt depends on two things, the chemical composition of the ash and the conditions under which it is melted. The most common causes of clinkers are the following: 1. A thick fire. 2. Stirring fire too much. 3. Slacky coal. 4. Closed ash pit doors. 5. Fire in the ash pit. Thick fires cause clinker by making it necessary to send a large amount of the air for combustion over, rather than through, the fire. In this way the ashes in lower layers of the fuel bed and on the grate bars become overheated. By stirring the fire the ashes on the grates are brought up into the hot zone of the fire and melted. Slacky coal sometimes makes a crust or blanket over the top of the fuel, thus stopping the passage of air in the same way as a fuel bed which is too thick. Closed ash pit doors and fire in the ash pit cause overheating of the grates and ashes above them. The remedies for clinkers are clearly indicated by stating the causes. Above all things do not allow blazing ashes and coals to accumulate in the ash pit. See Fig. 16. It is a good plan to keep water in the ash pit because of its cooling effect and because it extinguishes the hot coals which drop through the grates. It is also stated on good authority that a little lime mixed with clinkering coal will make the clinkers easier to break up. Banking Fires To keep the fire over night in a heating plant the fire may be banked at the side, front or rear of the furnace. The 46 A Short Course for Janitor-Engineers purpose of banking is to keep the fire burning slowly so as to have the means of making a quick, hot fire in the morning. In banking at the rear, the grates should have a little ashes left on them in front so that when the coal is raked toward the front in the morning the fine pieces will not drop through. The same precautions should be observed when banking the fire at the side or in front. Some firemen find it better to bank on the side because the fire can be turned over and spread in the morning with less loss of fuel through the grates than when the banking is done at the front or rear. To keep the fire over night it is not wise to close the stack damper tightly. Gas may accumulate and cause an explosion. In buildings heated by warm air furnaces it is often customary to let the fires die out at night, especially in locali- ties where woodworking plants provide an abundant and cheap supply of kindling. Questions 1. Explain the difference in the methods of firing hard and soft coal. 2. Describe fully your method of taking care of the ash pits and grates. 3. Under what circumstances would you open the firing door to govern the draft? 4. Would you use ash pit doors or the stack damper to regulate draft? Explain reason for your opinion. 5. Under what circumstances would you wet coal before firing? 6. A fireman claims that his coal clinkers badly. In examining his fire, state some things you would look for and some questions you would ask about his method of firing. 7. Explain your method of banking a fire. 8. Explain your method of cleaning a fire. 9. A fireman says that he is troubled with lack of draft. State several common causes for this condition and what you would recom- mend in each case. THE HEATING PLANT The most important part of a heating system is the boiler. It needs careful, intelligent attention, not only for the sake of economy, but for the sake of the safety of the occupants of the building in which it is located. Even a low pressure boiler may explode with disastrous results. The following is a good set of rules for operating low pressure heating boilers: 1. Blow out the water column and gauge glass and try gauge cock before starting fire in the morning. Do this several times a day. 2. Try safety valve and if found out of order, report it. 3. If sediment or sludge gathers in the boiler, blow the boilers through the bottom blow-off. Open the blow-off valves slowly and carefully, leaving them open three or four seconds, and close in the same way. Do not jerk the valves or open them suddenly. 4. When shutting off steam lines, shut the return valves first, then close the steam valves. There may be check valves in the line, but do not depend on them. The reason for this rule is that if the steam valve is closed first, the condensing steam causing a vacuum will draw the water out of the boiler into the piping and radiators. 5. Clean the flues with a good scraper at least every second day. 6. If damper regulators are used, shut them off at night. 7. Shut off the water glass at night. 8. When cutting in a new boiler on a battery have the pressure the same on all boilers and then open the main stop valve very slowly. 47 48 A Short Course for Janitor-Engineers Washing Boilers Before washing a boiler be sure to let it cool down for at least 24 hours. Let the water run out through the blow-off valve. Remove the handhole and manhole plates both at bottom and top of the boiler. Scrape out all loose scale and sediment in the bottom of the shell and starting at the top wash down with a hose and nozzle under good pressure. Wash the bottom of the shell thoroughly. Remove plugs from water column connection and bottom blow-off connection and wash the pipes out thoroughly with a good pressure. Boiling Out Sometimes a boiler, especially a new boiler, will foam because the grease, oil and foreign matter have not been thoroughly blown out of the system before starting. When a boiler foams the water level bobs up and down in the gauge glass, making it impossible to tell where the true water level is. If a surface blow-off or skimmer is attached to the boiler the floating grease and oil may be removed through it. Grease and oil cannot be blown out satisfactorily through the bot- tom blow-off. One thing to be done is to cool the boiler off and wash it out thoroughly. This may have to be done several times before all the grease is removed. The trouble with this method is that as the water settles down the grease clings to the side of the boiler and does not wash out easily. A more satisfactory method of cleaning the boiler is the fol- lowing: Fill the boiler full of water and remove the safety valve. Connect on a piece of pipe leading off to the floor drain. Put a valve on the end of the pipe so that a little pressure may be created by throttling. Start a slow fire and make the water boil rapidly, the grease and dirt rising to the top will be thrown out through the pipe in gulps. Keep the boiler full and continue boiling until the grease and dirt cease to spit out Remedies for Boiler Scale 49 through the valve. When the boiler is clean it may boil quite hard and no water will come out through the pipe even when it is very nearly full. Scale and Its Removal Boilers in which the same water is used over and over again give but little trouble with scale. In a boiler in which large quantities of fresh water are used, scale may give some trouble. The safest and surest way to avoid scale is to remove the scale forming ingredients before the water enters the boiler. This cannot always be done and hence we have need for various boiler compounds. In many cases the proper com- pound can be determined upon only after the water has been analyzed by a competent chemist. There are, however, two or three remedies with which every fireman should be familiar. Soda ash is the most common remedy. It is used and is ef- fective for a number of the most common scale troubles. Its action is to change the hard scale into a soft and easily re- movable scale. Caustic soda is also used, but is not recom- mended for general use except under the direction of some one who understands its properties. It costs more than soda ash, is a poison, has a corrosive action on the skin and causes vio- lent inflammation if it gets into one's eyes. Kerosene is another common remedy. It may be intro- duced drop by drop in some sort of sight feed apparatus or put in in small quantities some other way at frequent inter- vals. It does not have any chemical effect on the scale, but seems to loosen it and make it easier to remove. If the boiler is badly scaled up, kerosene may have to be sprayed in. To apply the kerosene properly empty the boiler while still warm and allow the scale to dry out. Then spray the kero- sene thoroughly over the scale and let it stand and soak in for six or eight hours. The scale will then be loosened suf- ficiently to be knocked off with a hammer. After knocking as much as possible clean the scale off thoroughly, otherwise 50 A Short Course for J anitor-Engincers pieces may continue to flake off after the boiler goes into service and settling down on the heating surfaces make trouble. Be very careful never to take a torch into a boiler treated with kerosene until it has been thoroughly washed and aired out. Kerosene and air form a highly inflammable and explosive gas. The boiler should not be entered with a light, or even with a well protected electric light, without thorough airing for the fumes may suffocate or at least overpower a man. Laying Up a Boiler. When a boiler is to be put out of service for some time, it should be emptied of water and thoroughly cleaned inside and out. Soot and ashes should be most carefully scraped and brushed from flues, tubes and shell and all ashes and dust removed from the ash pit. The interior of the boiler should be thoroughly cleaned out and aired. Manhole and hand- hole plates and all brass plugs should be removed so that there will be a free circulation of air, and the safety valve should be lifted from its seat. Some firemen build a small fire to dry out the boiler. This is not a good plan, as the boiler may get quite hot and be seriously injured. A small kerosene stove, if one is available, may be used for drying out. To keep mois- ture from gathering, put two or three shovelfuls of unslaked lime in a box in the boiler and on the grates. If the cellar is damp, swab the fire tubes with oil on a rag and paint the exposed surfaces of the boiler in the same way. Be sure that all water connections are shut off tight. Heating Systems Steam heating systems are the most common in school and other public buildings. Hot water is used to some ex- tent and warm air is adapted to dwelling houses and the smaller public buildings. Several new terms will be used in describing steam and hot water systems and in order to have them understood they will be defined at the outset. Heating Plant Definitions 51 Mains — Mains, as the name implies, are the main pipes leading from the boiler to the vertical pipes or risers. Risers — Risers are the vertical pipes from which the connections to the radiators are taken. These mains and risers are often called supply mains and risers to distinguish them from the return system. Returns — Returns is the general name given to all piping used to carry condensed steam from the steam mains back to the boiler. Radiator Runouts — Radiator runouts are the horizontal pipes connecting the radiators to the supply and return risers. Pitch — The pitch of a pipe is its slant or inclination from the horizontal. Relief or Drip — A relief or drip pipe is a small pipe connecting the steam to the return system or to a drain for the purpose of draining the pipe of condensed water. Water Line — The water line is the height at which water stands in the return pipes. This is higher than the water line in the boiler, but in a well designed system should not be more than 12" to 20" higher. Wet Return — A wet return is return pipe below the water level of the boiler. Dry Return — A dry return is a return above the water level of the boiler. A dry return carries both water and steam. Trap— A trap is an appliance placed between the steam and return system which allows water or air or both to be carried to the return, but prevents the steam from entering. Direct Radiation — Direct radiation is the name given to radiators placed in a room for the purpose of heating the air in the room over and over again. Indirect Radiation — Indirect radiation is the name given to radiators placed in ducts over which air passes on its way to rooms to be heated. Direct Indirect Radiation — Direct indirect radiation is the name given to radiators through which some outdoor 52 A Short Course for Janitor-Engineers air passes coming through a special inlet in the wall. Part of the radiator heats directly and part indirectly, hence, the name. Many of these same terms apply to hot water as well as steam. Supply mains in a hot water system are known as "flow mains" and the returns as "return mains." Steam Heating Systems. Steam heating systems may be gravity systems, that is, systems in which the water returns to the boiler by gravity, or they may be pump return systems in which the water is pumped back into the boiler. Gravity systems are again sub- divided into one pipe, two pipe and combination systems and the overhead distribution system. In the one-pipe system a single pipe suffices to carry the steam and return the water of condensation. In the two-pipe system the supply and return systems are entirely separate. In the combination system the radiators and risers are connected on the one- pipe system and the mains on a two-pipe system. This is a simple and satisfactory method for ordinary buildings. In the overhead distribution system a vertical steam main is run to the attic or top story and vertical risers carry the steam down through the building. Hot water piping systems are similar to steam systems and will not be separately de- scribed. The greatest difficulty experienced both with steam and hot water systems is the stoppage of circulation by air. The removal of air is accomplished in several ways. The simplest method is to force the air out by steam or water pressure. As air is lighter than water the air valve is at the top of a hot water radiator. Since steam is lighter than air the air valve should be at the bottom of a steam radiator, but to avoid flooding it is placed about two-thirds the height of the radiator from the floor. Air valves may be closed by hand or may be made to close automatically against the steam. In hot water systems Steam Heating Systems 53 the air valve is usually opened and closed by hand by means of a key. Forcing the air out by steam pressure is not always satisfactory, especially in large systems, hence we have the vacuum systems in which the air is removed by a steam ejector or by a pump, and the vapor systems in which the system is filled with steam and then automatically sealed by traps. The condensing steam causes a vacuum. In the vacuum systems the pressure is always less than atmospheric and con- sequently the temperature is less than 212°. In the vapor systems the pressure is usually atmospheric or a few ounces above and the temperature consequently is 212° or slightly higher. The advantages of vapor and vacuum systems are: positive removal of air and condensation; little or no danger from frost or leaks; rapidity of circulation and consequent rapid heating even in long runs of piping; small pipes and hence low cost of installation. In the vacuum and vapor systems some form of automatic valve is placed at the end of each radiator, which allows water and air to pass readily, but closes against steam. There are two types of these valves: the thermostatic and the float valve. In the thermostatic valve the heat of the steam expands a piece of metal to close the valve or evaporates a liquid inside of a sealed receptacle, which by its expansion closes the valve. In either case the heat, by means of ex- pansion, causes the valve to act. Float valves have a float which lifts the valve from its seat when water accumulates and allows the water to flow into the return. An auxiliary passage is provided for the air. Dirt is the great enemy of valves and traps and to keep a system working perfectly, dirt and grease must be kept out of it. Water hammer or pounding in the radiators is very an- noying to the occupants of a room, hence every janitor should do all in his power to prevent it. Water hammer is caused by 54 A Short Course for Janitor-Engineers One cause of pounding A radiator tilted the urong way. rig 19 How a portial/y closed valve >5 tops arcu/ation of steam water in the system coming in contact with steam, hence, to prevent it, avoid water pockets. One of the most common causes of water hammer is the gathering of water above a leaky or partially closed radiator valve. For this reason radiator valves on a single-pipe or combination system should never be partially closed because this prevents the escape of the water from the radiator run-out. See Fig. 20. Sometimes a radiator with a single connection settles at the end farthest from the connection. Water gathering at the low point is almost sure to cause hammering. To remedy the difficulty raise the low end of the radiator so that it can drain. See Fig. 19. Water is sometimes forced up into radiators from the returns due to clogged valves or pipes or because the returns are too small for the radiation. If water backs up in this manner the return valves and piping should Placing Radiators 55 be examined. Long wall coils must be carefully drained and pitched evenly or water pockets will form. In systems in which the heating coils are controlled by thermostats and diaphragm valves the pressure should not be run up too high in order to force steam through and heat rapidty. A pressure of more than ten pounds distorts the ordinary diaphragm valve and prevents its working easily. Five pounds should be sufficient to operate such a system. Too high pressure will also cause water hammer, due to the fact that considerable water is trapped in the radiator above the valves. One very important point to be kept in mind about re- turn piping is that it may contain a large amount of water, in some cases as much or more than the boiler. A second very important point is that no water can return to the boiler in a gravity system unless the water in the returns stands at least as high as the water level in the boiler. If the returns have been drained for any reason, say to prevent freezing, great care must be exercised in opening them to see that the water in the boiler is maintained at the proper level. The returns must be filled before any water returns to the boiler from the system. If the water in the boiler is evaporated to fill the returns without supplying fresh water, low water and a burned or cracked boiler will result. Direct and Indirect Systems In a direct or direct indirect system the radiators should be under a window or along the coldest side of a room. When radiators are so placed the best circulation of air is secured. In the indirect heating system (radiators below the floor and air passing over) the registers should be on the inner or un- exposed wall of the room, a system just opposite to that em- ployed in direct heating. Indirect radiators should always be connected on the two-pipe system because there is so much condensation to be carried off. In operating an indirect or 56 A Short Course for Janitor-Engineers direct-indirect system the dampers letting in the outdoor air should be closed at night in order to avoid waste of fuel in heating unnecessary fresh air, and also to avoid freezing. Circulation of air is absolutely necessary for proper heat- ing. Air must come into the room and go out or must move about in the room. A radiator will not heat if the air does not circulate through it. Books or shelves should not be placed on radiators as they prevent the rise of air between the sec- tions and thus impede circulation. Opening a window for a time even on a cold morning will often start circulation and cause a room to heat up more quickly than if the window is kept closed. Circulation may often be established through doors opening into other rooms or halls. In a church or other building heated at comparatively long intervals a sluggish circulation may be started by placing an electric fan near a radiator and blowing air over it. Warm Air Systems So far nothing has been said in regard to warm air heating systems. Firing methods, as described, apply to all heating systems. Due to the fact that a warm air system warms a building rapidly, fires are often allowed to go out during the night and are rekindled in the morning. This is desirable in mild weather, especially if a good supply of kindling is avail- able, as in a town where there are large woodworking industries. In operating a warm air system care must be exercised to see that the air has a chance both to enter and leave the room. Air cannot be forced into a room by a furnace if it cannot get out at the same time. Outdoor and indoor air circulation systems will be discussed under ventilation. By regulating the volume dampers in the basement leaders, the flow of air to different rooms can be controlled. Direction of wind makes a great deal of difference and this must be watched and the system operated accordingly. Long pipes, poorly in- sulated pipes, pipes with many turns and bends and pipes with Questions and Problems 57 but little pitch are the most difficult to send the warm air through. These must be watched and sometimes started by- closing off other pipes until a circulation is established and the pipe warmed up. A warm air system must never be entirely closed either with the volume dampers or the floor registers. This prevents air circulation over the heating surfaces and the furnace will crack and burn out exactly as an empty boiler burns out if exposed to a hot fire. For school buildings in the daytime the air supply should come from outside. At night means should be provided for the circulation of the in- side air after the building has been well aired out. This saves fuel. Questions 1. Having a boiler with full steam pressure on, explain how you would empty it and prepare to inspect it. 2. Explain your method of laying up a boiler for the summer season. What is the object of lifting the safety valve from its seat? 3. What effect does oil have if it gets into a boiler? 4. What do you look for in case a radiator pounds? 5. What is the advantage of admitting steam at the top of the radiator on one side and taking the condensation out on the other side at the bottom, as in a vapor system? 6. Explain the reason for using a steam trap and how it works. How does an air valve work? What is the chief cause of trouble in steam traps? 7. Engineer A says it is a good plan to drain the returns of a steam heating system so as to form a partial vacuum in the coils, thereby giving a quicker circulation of steam. Is he right? 8. If a leak started in a pipe on the third floor of a building heated by hot water, what would you do? 9. What is the object of having a check valve on the return line of a steam heating system? 10. When shutting off a steam system, would you shut the return or supply valve first, and why? 1 1 . Engineer A says there is no use in having a governor to control 58 A Short Course for Janitor-Engineers the vacuum pump on the return line, it ought to run all the time anyhow in order to keep up the vacuum and take out the water. Is he right? 12. A schoolhouse is heated by a gravity single line system. The teacher persists in partially closing the radiator valves to regulate the heat. She says in other schoolhouses they regulate the heat that way and she doesn't see why it cannot always be done. Explain the difficulty. VI. GOOD AND BAD AIR The janitor or engineer is the custodian of the health and safety of the occupants of his building. It is not enough to keep the rooms at a proper temperature, fresh, pure air, properly conditioned is absolutely necessary to health. Its importance is illustrated by the fact that a man can live three weeks without food, three days without water and three minutes without air. Prof. S. H. Woodbridge, of Boston, says "death rates have been reduced by the introduction of efficient ventilating systems in children's hospitals from 50 per cent to 5 per cent; in surgical wards of general hospitals from 44 to 13 per cent; in army hospitals from 23 to 6 per cent. For young and growing persons such as those in our schools, fresh air is especially necessary. Bad air causes headache, lassitude and mental weariness. It is also both a direct and indirect cause of tuberculosis, diphtheria, measles, scarlet fever and other diseases. Germs of disease may be directly communicated from one person to another in the foul air or his vitality may be so lowered by breathing foul air that when exposed to disease elsewhere he is unable to resist it. Sore throats, colds and various lung diseases are the most common bad air diseases. The human body con- tinually gives off moisture and odors and sometimes disease germs. If air in a room remains still and stagnant a thin blanket of warm, moist air forms around the body and pro- duces a feeling of stickiness and discomfort. This blanket must be swept away by currents of fresh air if we are to be kept comfortable. Anyone who has been confined in a close, crowded room knows what discomfort bad air causes. Before we can explain the difference between good air 59 60 A Short Course for Janitor-Engineers and bad air we must know something about the composition of air. Air is a mixture chiefly of nitrogen and oxygen, 4-5 being nitrogen and 1-5 oxygen. Oxygen is the vital part which we breathe into our lungs. Nitrogen dilutes the oxy- gen. Carbonic acid gas, or C0 2 , as it is called, is present in small quantities in good, pure air, usually measured as so many parts in 10,000. Good, pure air contains 3 to 4 parts in 10,000. Water vapor also exists in the air in varying quanti- ties, depending on the temperature, the wind, and whether bodies of water are near. Dust and other impurities are also present in varying quantities, depending on the location. Just at present engineers are somewhat uncertain as to just what "bad air" is. Some standard is necessary. For many years the carbonic acid or C0 2 standard has been used. According to this standard, pure air contains 3 or 4 parts of C0 2 in 10,000. Air containing 4 to 8 parts in 10,000 is still good. Air containing more than 8 parts is not considered good air. This standard is not altogether satisfactory, but at present is the best we have. The amount of C0 2 present, how- ever, must not be considered a conclusive test of the purity or impurity of air. Other things affect it as we shall see. The question naturally arises as to where the C0 2 comes from. It comes from the breath and from the burning of various sub- stances in the air such as gas jets, lamps, candles, coal fires, wood fires, etc. Most of it, especially in school buildings, comes from the air breathed out by the occupants. If air con- taining four parts in 10,000 of C0 2 is breathed into the lungs it will contain about 400 parts in 10,000 when breathed out, or about 100 times as much. This air is totally unfit to be breathed again. Hence, large amounts of fresh air are neces- sary to keep the proportion of C0 2 as low as 6 to 8 parts in 10,- 000. The amount of fresh air necessary may be calculated as follows: Suppose we desire to keep the C0 2 contents down to 6 cubic feet in 10,000 cubic feet, and suppose the fresh air Human Breathing Requirements 61 • 6 4 contains four cubic feet in 10,000 10,000 10,000 2 2 cubic feet increase allowed. expressed as 10,000 10,000 a decimal is 0.0002. Every adult person gives off about 0.6 cubic feet of C0 2 per hour, hence, the amount of air to be sup- plied per person is 0.6 -r- 0.0002 = 3,000 cubic feet per hour. If the proportion of C0 2 is raised to eight parts in 10,000 this allows an increase of 0.0004 and the air necessary per person is 0.6-^0.0004 or 1,500 cubic feet per hour. At the pres- ent time not less than 30 cubic feet per minute per person, or 1,800 cubic feet per hour are considered necessary for healthful conditions. Gas jets also vitiate the air in a room. One gas jet vitiates as much fresh air as 3 to 5 persons. Electric lights do not affect the air in this way. The American Society of Heating and Ventilating Engineers has for many years been studying the problem of maintaining conditions of health and comfort in various classes of buildings. The following recommendations are of particular interest to men in charge of buildings as indicating what these engineers consider to be minimum requirements for floor space, cubic contents, air supply and regulation and temperature: Space Per Occupant (Minimum Requirement) Schools and colleges — class, study, lecture and recita- tion rooms, floor area per occupant in square feet — 15. Schools and colleges — class, study, lecture and recita- tion rooms, cubic space per occupant (volume divided by number of persons) in cubic feet — 180. Primary schools — class and study rooms (pupils under 8 years of age), floor area per occupant in square feet — 12.5. 62 A Short Course for Janitor-Engineers Primary schools — class and study rooms (pupils under 8 years of age), cubic space per occupant in cubic feet — 150. Theatres, auditoriums and court rooms — floor space per occupant in square feet — 90. Factories, manual training rooms and other work rooms — cubic space per occupant in cubic feet — 250. Minimum space conditions in all classes of buildings or rooms not tabulated shall be reasonable and practical and shall meet the approval of the Department of Health. Air Supply (Minimum Requirement) The supply of outdoor air for the following classes of rooms shall be positive and based on a minimum quantity of cubic feet per occupant per hour as tabulated: Class, study, lecture and recitation rooms in all schools and colleges, cubic feet per occupant per hour — 1,800. Theatres, court rooms and other auditoriums — 1,200. Factories, manual training rooms and other work rooms —1,500. All air supply for ventilation must be from an uncon- taminated source or air from which the dust or other impuri- ties shall be sufficiently removed by washing, or otherwise, subject to the approval of the Department of Health. Air Distribution The distribution and temperature of the air supply for ventilation shall be so arranged as to maintain the temperature requirement, without uncomfortable drafts, or any direct draft lower than 60° F., and as a test of proper supply and distribution, it shall be required that the C0 2 content shall not at any time exceed 10 parts in each 10,000 parts of air, based upon tests of air samples taken in a zone from 3 to 6 feet^above the floor line in any part of the occupied spaces. This requirement may be modified by the Department of Tijyes of Ventilating Systems 63 Health or other properly constituted authority as applying to breweries, water charging rooms or other rooms where carbon dioxide is liberated in manufacturing processes. Note: While carbon dioxide in the air, in reasonable quantities, is not considered injurious to health, its presence in occupied rooms is an accurate measure of the air supply and distribution if no other source of carbon dioxide is present except the occupants of the room. Temperatures The temperature of the air in occupied rooms in all classes of buildings, during the periods of occupancy, shall be not less than 60° F., nor more than 72° F., except when the outside temperature is sufficiently high that artificial heating in the building is not required. This requirement shall not apply to foundries, boiler or engine rooms, or special rooms in which other temperatures are required or advisable as approved by the Department of Health. Systems of Ventilation There are in general use three methods of ventilation. 1. Natural methods, in which open doors, windows, flues or chimneys are used to introduce the fresh air and remove the foul air. 2. Ventilation by aspiration or systems in which the natural draft of a chimney or flue is increased by heaters or heating coils. 3. Forced ventilation (sometimes called mechanical ventilation) or a system in which a fan is used to supply air or remove it from a room or both. The natural method of ventilation is the simplest of all and also the most unreliable. The amount of air coming in through windows, doors and cracks is extremely variable and hard to control. It has been shown by tests that the air 64 A Short Course for J anitor-Engineers leakage into and out of a room of average construction amounts to one to three changes of the entire contents per hour. In practice it is customary to count on at least one change per hour when considering the matter of ventilation. For dwelling houses with direct steam or hot water heating, very fair ventila- tion may be obtained by this method under certain conditions. For example, a room 12'xl2'x8' contains 1,152 cubic feet. Allowing one and one-half changes of air per hour gives a supply of nearly 1,800 cubic feet, a fair amount for one person. Double windows, weather strips, storm doors, etc., restrict the leakage; hence, many houses are poorly ventilated in the winter time and we find the occupants suffering from colds and sore throats. Naturally, this method is not adapted to any building or room where there are a number of occupants. If fresh air and foul air ducts are provided, conditions are somewhat better, but any system which depends on the natural movement of air for circulation is uncertain and should not be depended upon where large amounts of fresh air are necessary. The aspiration method aids in removing the foul air from a room by warming the air in the foul air flue, thus creating the draft. Fresh air comes in as the foul air goes out through warm air registers, around direct and indirect radia- tors and through windows and doors. If the aspirating coils are supplied with steam or if the air is warmed by a separate heater, the operating cost of this system of ventilation is high because a large amount of heat is required to create a small air movement and the heat is lost. If the heat of the flue gases in a chimney is used to warm the air in the foul air flue the cost may be neglected, as this heat would be lost anyway. Even when supplied with heating coils a vent flue is not posi- tive in its action. When the wind blows in a certain direction there may be a draft down instead of up the flue. This is one objection to this method of ventilation, but the principal one is its lack of capacity, hence, it is suited only to rooms which have a small number of occupants for their size. Forced Ventilation 65 Forced or mechanical ventilation is the method best suited for school buildings because the amount of air supplied is under control at all times and independent of wind or weather. There are two ways in which the air maybe supplied, the plenum method and the exhaust method. In the plenum method the air is forced into the room under a slight pres- sure. The foul air escapes through vent flues in the walls, being forced out by the incoming fresh air. In the exhaust method the foul air is sucked or drawn from the rooms by a fan. The fresh air rushes in to take the place of the foul air drawn out. In some cases a combination of these two systems is used, one fan drawing out the foul air and one fan forcing in the fresh air. This is known as the balanced system. In many cases the ventilation system also supplies the air for warming, as in the case of a warm air furnace or indirect radiation. The term "fan system" is applied to all systems in which air is supplied by a fan, the heating being done usually by steam, though in some cases the air is forced over the heating surfaces of a furnace. There are two kinds of fan systems in use, the direct and the indirect. In the in- direct system all the heating is done by steam coils or a warm air furnace near the fan, and the air for ventilation carries this heat to all parts of the building. The temperature of the air is regulated according to weather conditions by the steam coils or heating surfaces over which the air is passed. In the direct system, the air supplied by the fan is heated only to the room temperature of about 68°. The fan supplies air for ventilation only. The rooms are kept at proper temperature by radiators in- stalled in the rooms. Figure 21 is a diagram of an indirect fan system. The fresh air is drawn from outside through the window on the right. It first goes through a tempering coil where the tem- perature is raised to 60° or 70°. The temperature is con- trolled by the by-pass damper below the tempering coil. This INDIRECT F/1N SYSTEM Fg£l DIRECT INDIRECT F/IN SYSTEM. Fg.ZZ 06 Types of Fan Systems 67 allows more or less of the air to pass directly to the fan without being heated. If necessary, steam may be shut off from some of the coils. After leaving the fan, part of the air is forced over more heating surface, which raises the temperature much higher. It then enters the large chamber at the left, known as the plenum chamber or plenum room, because the air is under a slight pressure here. The plenum chamber contains two compartments; one receiving all the air passing over the heating coils on the discharge side of the fan and the other receiving only the tempered air passing below the heating coils. From the plenum room ducts lead to the rooms to be heated. Mixing dampers allow hot air, tempered air or a mixture of both in varying proportions to be supplied to the different rooms. A mixing damper is so made that as one leaf leading to one compartment opens the other one closes. This admits a constant quantity of air, but controls the pro- portions of heated and tempered air. The heating coils on the discharge side of the fan are controlled by thermostats or hand valves. In mild weather a number of them can be shut off. As will be shown later, some provision should be made for moistening the air. Steam jets are satisfactory for this purpose, and are placed between the tempering coils and the fan. The foul air vent for the room is shown near the floor at the opposite end of the room from the warm air register. Figure 22 shows the direct-indirect fan' system. The room is heated by steam coils or radiators, the fan supplies air for ventilation only. The cold air from outside is heated to room temperature only by tempering coils. The by-pass damper allows more or less of it to pass over the heating coils in order to meet the requirements of varying outdoor temperature. The plenum room communicates directly with the ducts leading to different rooms. The dampers regulate the amount of air going to different rooms, but not its temperature. The 68 A Short Course for Janitor-Engineers Air Window open at bottom window board /4tr check for outside intake r7f.Z4 check wire netting' Board to checA direct draft F7g.M foul o/r gang OUT Ar check for inside vent flue n g z5 steam jets for moistening are also necessary and should be located as shown. Operation of Natural and Aspiration Systems Windows are an uncertain method of ventilation and the direction of the draft through them depends largely on the wind. In general, however, to ventilate a room and cool it, the windows should be opened at the top, because the warm air is at the top of the room. To get fresh air in where it can be breathed the windows should be opened at the bottom, if possible on opposite sides of the room, so as to get a current of air through the room. If windows are not placed on oppo- site sides of the room some windows should be open at the top and some at the bottom. To prevent drafts from striking occupants seated near a window a board may be placed as Natural Ventilation 69 shown in Fig. 23. In some schools large screens of unbleached muslin have been made and inserted under the sash-like fly screens. These keep out dust and prevent draft and are said to give good ventilation. They are, however, likely to be- come dirty and unsightly in appearance. In cold weather it is a good plan to open a window at the bottom over a radiator if the air blows in. In this way the air is warmed somewhat before passing into the room. If, however, the air blows outward, heat will be wasted. It is not a good plan to open a window at top and bottom over a radiator because the air is likely to circulate in and out without passing into the room. Refer to Fig. 3. Care should be exercised in opening windows in toilet rooms. If the air blows in strongly, odors will be carried into the building. All rooms should be thor- oughly aired out several times a day. Doors and windows should all be opened, giving the fresh air currents a chance to sweep the foul air out. Foul air ducts are often located in a wardrobe or cloak room. When this is the case, be sure that overcoats and coats are not hung so as to cover them up. The surest way to avoid such a possibility is to remove all hooks from above the foul air register. In an aspiration or natural system there will sometimes be a strong back draft down the foul air flue on windy days. To prevent this from blowing back into the room, curtains or flaps can be installed as shown in Fig. 25. These close against the grating if air blows down the flue, but do not obstruct the outward passage of the air. These foul air ducts should be closed at night after the building has been thor- oughly aired. In case a building is heated with a furnace or by indirect radiation the cold air inlets should have doors opening in- ward which can be regulated with rope and pulley and held in any position. They should not flap up and down. At night these doors should be closed and the air of the building recirculated. During the day they should be regulated ac- 70 A Short Course for Janitor-Engineers cording to varying conditions of wind and temperature. Nothing should interfere with opening the door to full ca- pacity when necessary. Cold air inlets and ducts should be kept as clean and free from dust as possible. Clean, pure air cannot come from a dirty, dusty, ill-smelling duct. A form of check for an outside air intake is shown in Fig. 24. The Operation of Fan Systems The fan system is most satisfactory to operate because the air supply is under control at all times. Foul air and fresh air inlets and ducts should receive the same care and attention as in the case of the natural and aspiration systems. In warming up the building air should be recirculated as ex- plained before. During the day all the air supply should come from the outside. Mixing dampers will need care and adjustment from time to time. Using a fan with a direct heating system will be found to economize steam in the radiators because the circulation of air equalizes the tem- perature at floor and ceiling. Without the fan the tempera- ture may be 10° to 20° higher at the ceiling. By starting the fan, a room temperature may be raised several degrees by circulating the air from ceiling to floor level without ad- ditional heat. In heating up an empty building in the morn- ing with a fan system the air in the building should be re- circulated so as to economize fuel. Outside fresh air is not necessary until the occupants arrive. To save fuel, cold outside air should be used sparingly whenever the rooms are empty. One great difficulty in operating a fan system satis- factorily is caused by opening windows in different parts of the building. Windows should be opened from time to time in order to flush the building out, but in order to interfere as little as possible with the fan system all windows should be opened at the same time. The following plan adopted in Chicago has been found to give good results: Handling a Ventilating System 7 1 Directions to Janitors "The principals, with the co-operation of the teachers, will arrange for flushing the rooms with fresh air by the opening of windows and classroom doors throughout the building at practically the same moment, in order that advantage may be taken of the prevailing wind. The temperature of the rooms should not be allowed to fall below 55 degrees, Fah., and the responsibility for the habitable condition of the classrooms will be placed upon the respective teachers. In extremely cold weather the windows should be opened but slightly and careful attention given to prompt closing of same. Except where special permission is given by the Chief Engineer, win- dows are to be opened during these periods only: "Recess in morning session; close of morning session; re- cess in afternoon session. "Whenever the atmospheric conditions are such that the mechanical system of ventilation is closed down, the principal will be notified of same. It is suggested that the principals and engineers of buildings agree on a series of signals which may be given on the school gongs; such a system is now in operation in a number of buildings. "One ribbon §"xl4" will be placed over each heat inlet where practicable, and teachers are urged to communicate at once with the principal should this ribbon indicate a clos- ing down of the mechanical system at a time when it should be in operation. Windows and doors are to be opened as well as closed by the teachers." As has been said, there is some uncertainty in regard to the amount of fresh air necessary and the advisability of re- circulating washed air. The following conclusions of the Chicago Commission represents safe practice and are worthy of the attention of every janitor and engineer: 72 A Short Course for J anitor -Engineers Conclusions of the Chicago Commission on Ventilation in Regard to the Heating and Ventilation of Schoolrooms Resolved, That either the plenum or vacuum principle is applicable to the ventilation of schoolrooms. Resolved, That in the artificial ventilation of a school room, the air inlets and outlets should be of such size, number and location as to insure equal distribution of air throughout the room. Resolved, That the maximum temperature for a school room, artificially heated, should not be more than 68 degrees F. Resolved, That in the present state of knowledge and practice the quantity of air supplied to schoolrooms for ventilation should not be less than 30 cubic feet per pupil per minute. Resolved, That both the design and location of the air intake for a school building should be such as to minimize the possibility of contaminating the air supply. Resolved, That efficient air cleaning devices are desirable in all ventilating installations where the air supply is liable to be contaminated by dust, or other objectionable matter. Resolved, That in the automatic control of temperature within a schoolroom, the thermostat should be so located as not to be influenced by wall chill. The thermostat should be so located as to be influenced by the average temperature of the room only. Resolved, That in mechanically ventilated school build- ings, it is desirable at stated periods to flush all the school rooms in the building with fresh air by means of open windows. Resolved, That careful consideration should be given to the sweeping and cleaning of the school room as affecting its ventilation. Questions on Ventilation 73 Resolved, That the carbon dioxide content alone is not always an index of the contamination of air for ventilating purposes, within an enclosure. Questions 1. A teacher says that the way to ventilate a room is to open all the windows at the top so that air will come in at some and go out at others. Is this correct? 2. Would you prefer, when running a fan system, to have all the windows in the building opened at once for airing out and all closed at once or to have them opened a few at a time at intervals? 3. In a certain school building in which there is a fan system of venti- lation and direct steam for heating, the teachers complain that soon after the fan is shut down there is a cold draft along the floor. What causes it and what remedy would you suggest? 4. A building is dependent for ventilation on windows and doors. The teacher says she cannot open the windows on account of the cold draft on the pupils. How would you remedy the difficulty? 5. In a building heated with a warm air system, the warm air goes out the cold air duct when the wind blows in a certain direction. Sug- gest a remedy. 6. Engineer A says that a thermometer placed in moving air or a draft will show a lower temperature than when placed in the same air when still. He says moving air always feels cooler and is cooler than still air. Is he right? 7. In school buildings provided with a fan system, the fresh air ducts are usually at the ceiling and the foul air ducts near the floor. In a kitchen or restaurant the foul air ducts are near the ceiling. Why? 8. Explain the difference between the direct and indirect fan sys- tems and the advantages of each. 9. In a certain school building in which air was washed and recircu- lated it was found that less steam was required to keep the building warm when the fan was running than when the fan was shut down. How do you account for this fact? 10. Explain what you would do in shutting down the following sys- tems for the night in cold weather: (a) indirect fan system, (b) direct fan system, (c) direct and direct indirect steam radiation without fan. VII HUMIDITY Proper temperature and proper ventilation are neces- sary for the comfort and health of the occupants of a building or room, but they are not the only conditions necessary. Proper humidity or moisture in the air is just as important as proper temperature and ventilation. That air contains moisture, we know, for we can see it in the form of fog, rain or snow. Sometimes we cannot see it when it is in the form of water vapor or steam because steam is invisible. Ordi- narily we think of steam as being hot, but the invisible water vapor in the air is steam just as truly as the steam in a boiler, only it exists at a lower temperature. When the invisible vapor condenses we see it as water or ice, in the form of fog, rain, snow or the sweat on a pitcher or pump on a sultry sum- mer day or frost on our windows in winter. Air is like a sponge, for it will absorb and hold various amounts of water vapor, depending on its temperature, just as a sponge will absorb various amounts of water, depending on its size and texture. Warm air is like a large, soft sponge, which will hold a great deal of water. Cold air is like a small, hard sponge, which will not hold much water. In other words, the capacity of air for moisture increases as the temperature increases. This does not mean that warm air always contains more moisture than cold air any more than a large, soft sponge always contains more water than a small, hard sponge. Warm air will absorb and contain more moisture than cold air if the moisture is available. Naturally, more moisture is avail- able near the ocean or lakes than in inland districts; more in the valleys than on mountain tops, and more in the forests than on the open prairie or sandy deserts. Carrying the example of the sponge a little further, we know that to get the water out of it, we squeeze it. To get 74 Relative vs. Absolute Humidity 75 the water out of air we do not squeeze it, but cool it and the vapor condenses to water. This is what happens when a warm, moist current of air is chilled by a cool breeze. Down comes the moisture in the form of rain. Drops gather on the side of a water pitcher or pump on a sultrv day because the air near the pitcher or pump is cooled and the water vapor condenses. If the temperature is below freezing, we get snow instead of rain and frost instead of water drops. The moisture in the air is called its humidity. The humidity may vary from the maximum amount of moisture which the air can contains at a given temperature down to almost nothing. When considering proper air conditioning, the important point to be noted is that it is not the actual amount of moisture present that determines whether the air feels dry or moist. It is the amount of moisture contained in the air compared to what the air could contain at that temperature, if it had all it could hold. Here again the sponge is a good illustration. We judge whether a sponge is wet or dry, not by the actual amount of water contained, but by the amount contained compared with what it could hold if saturated. The amount of moisture actually in air compared to what it could hold is called the relative humidity and is expressed in percentages. For in- stance, the relative humidity at a certain time may be given as 40%. This means that the air has in it 40% as much moisture as it could hold in a saturated condition at the same temperature. Weather reports give the relative humidity at different times of day on different days. The following are examples : Humidity at 12 M 70% Humidity at 4 P. M 40% Relative humidity tells us nothing directly as to the actual amount of water present in the atmosphere and, as has been said, this is not important for our comfort. The actual amount of water present in the air at any time is called 76 A Short Course for Janitor-Engineers the absolute humidity and is sometimes given for scientific reasons. Humidity tables give the absolute humidity as so many grains per cubic foot. One grain is 1-7000 of a pound. For instance, air at 70° may contain 6 grains of moisture per cubic foot. It might contain 5 grains, 4 grains, 3 grains, or any quantity down to nothing. It could never contain more than 7.98 grains per cubic foot at 70° because that is all the air will hold at that temperature. It is then said to be satur- ated or to have a relative humidity of 100 per cent. Humidity tables may be found in scientific textbooks or in commercial catalogs such as that of the Carrier Air Conditioning Co., New York City, or the Buffalo Forge Co., Buffalo, New York. To show the variation in the capacity of air for moisture at different temperatures the following table is given. The weight of moisture contained is stated in pounds per 1,000 cubic feet instead of grains in one cubic foot. Note that the amount of moisture stated is what the air contains in a satur- ated condition at the given temperature. Lbs. Water Vapor Temperature Contained in 1000 of Air °F. Cubic Feet of Air 0° 0.068 12° 0.122 22° 0.194 32° 0.301 40° 0.407 50° 0.583 60° 0.821 70° 1.140 This table clearly shows that warm air can hold much more moisture than cold air. The relative humidity may be determined, provided the temperature and moisture content are known. For instance, suppose the temperature is 60° and the moisture content 0.35 pounds per 1,000 cubic feet, Relation of Humidity to Temperature 11 what is the relative humidity? Saturated air at 60° contains 0.821 pounds in 1,000 cubic feet. Since this air contains only 0.35 0.35 pounds, the relative humidity is = 0.42 or 42%. 0.821 Another problem is to find the actual moisture content when the temperature and relative humidity are given. Suppose the temperature is 40° and the relative humidity 60%, what is the absolute humidity? Saturated air at 40° contains 0.407 pounds per 1,000 cubic feet. With 60% humidity it contains 0.407X0.60 = 0.244 pounds per 1,000 cubic feet. In the same way, the actual amount of moisture for any relative humidity can be calculated. Outdoor air in this sec- tion of the country has an average relative humidity of 70%. In dry desert regions the relative humidity may go down as low as 12% to 25%. We often hear the statement that heating air dries it out. This is not true. Air cannot be dried out by heating it like a sponge or a wet rag. The relative humidity is lowered when air is heated and this affects our health and comfort. Let us see how this happens. Suppose that outdoor air, having a temperature of 32° and a relative humidity of 70%, is taken into a building and heated to 70°. The actual amount of moisture in the air is not changed, but the relative humidity drops to 17%. The reason for this is as follows: Saturated air at 32° contains .301 pounds of moisture per 1,000 cubic feet. At 70% humidity, as stated, it contains 0.301X70 = 0.210 pounds per 1,000 cubic feet. When the air is heated the 1,000 cubic feet expand to 1,077 cubic feet. Hence, in every 1,000 1,000 cubic feet of air there are X0.210 pounds of 1,077 78 A Short Course for Janitor-Engineers Air Temp Depre^o/on, or Difference be/ween Dry and kA?f- bu/b Tbermomefers. 3 2 5 6 7 9 70 II l£ ,'3 74 15 /6 37 63 19 20*27 \ 22\23 2425 60 tij 73 73 68 63 98 93 49 44 40 35 37 27 36 17 II 9 1 1 61 84 78 74 68 64 99 54 DO 45 40 36 52 28 24 78 74 IO 3 2 62 64 79 74 69 64 60 05 50 46 47 37 33 29 25 2V /6 12 ff 4 1 e* 79 74 70 65 60 56 9/ 47 42 38 34 %> 26 Z7 19 13 7 5 £ 64 84 79 75 70 66 6/ 56 92 4& 43 33 35 9/ 27 22 23 75 9 7 4 / 65 85 80 73 70 66 62 57 53 48 44 40 36 32 20 24 27 76 77 8 5 3 66 ' 65 80 . '6 71 66 62 63 53 49 45 47 37 3329 .35 22 77 /£ 70 7 4 67J85 80 76 7/ 67 62 f£ 54 50 46 42 38 34 30 26 23 78 14 77 8 6 7 97 76 72 67 6? 59 55 5/ 47 43 39 35 3/ 27 2<4 3C 75 73 IO 7 j 6909 1 87 77 72 6B 64 59 55 5/ 47 44 40 36 32 28 25 2/ 16 74 77 9 4 1 70\86 3/ 77 72 69 64 60 56 52 48 44 40 37 33 29 27 22 77 75 12 70 6 3 7/ \&6 II 82 77 73 69 64 60 56 03 49 45 4/ 38 34 30 28 23 13 76 73 72 7 4 72 \&6 6.2 78 73 69 69 6/ 97 53 49 46 42 39 35 71 29 33 20 63 75 75 3 5 73 86 82 73 73 70 65 6/ 'j,3 94 50 36 43 40 36 32 £9 25 2/ (9 76 14 70 6 74 36 82 78 74 70 56 62 98 54 5/ 47 66 40 37 73 50 26 23 £3 /7 75 77 7 75 ee as- ?e /.- 70 66 63 99 55 5/ 48 13 3/ 33 34 3/ 27 .31 2/ (6 76 72 8 Fig. 26 moisture = 0.195 pounds. Air at 70° when saturated contains 1.140 pounds in 1,000 cubic feet. This heated air contains 0.195 only 0.195 pounds. The relative humidity is = 17%. 1.140 The air has not dried out, but the relative humidity is greatly decreased due to the fact that the warm air could contain so much more moisture than it actually does contain. It makes no difference whether the air is heated by steam, hot water or a furnace, the effect is the same. In making ordi- nary, quick calculations it is not necessary to allow for the expansion of the air, as was done in the preceding example. Effects of Humidity 79 Simply take the moisture content of the air with the humidity given and divide it by the moisture content of saturated air at room temperature. In the above example by this 0.210 method we would have = 18% instead of 17% when 1.140 accurately calculated. If the outdoor air were very cold the difference would be greater. Effects of High and Low Humidity From the foregoing discussion it is clear that the air in artificially heated rooms must be much drier than outdoor air. In most cases the indoor air is too dry for health and com- fort in the winter time. It shrivels the skin, dries out furniture, kills plants and allows various bad air diseases to develop, due to its effect on the glands of the throat. These little glands under normal conditions discharge a fluid which kills disease germs. If the air is too dry, they discharge water only in order to keep the throat moist. If germs are breathed in they can grow and develop because the germicidal fluid is not present. Many persons when compelled to breathe very lemoerma \\ Heater u j! / /iir Washer r : ~> To c/osi rooms Fig. 27. Side View of Air Washer and Fan. 80 A Short Course for Janitor-Engineers dry air are immediately troubled with a hacking cough and a sore throat, no doubt due to these disease germs, which under normal conditions would be killed. Dry air in a room also causes the occupants to feel nervous and feverish. Another effect of dry air is to make us feel chilly even a t a temperature of 70°. To understand this we must bear i n mind the fact that evaporation of moisture cools the surface from which evaporation takes place. Alcohol, ether, gasoline or any volatile liquid feels cool when poured upon the hands because it evaporates so easily. Perspiration evaporating from the body cools it in the same way and the drier the air the more rapid the evaporation and the greater the cooling effect. If the air is very dry, our bodies are cooled so much that we feel chilly. It is for this reason that a room at 68° properly humidified feels more comfortable and just as warm as a room at 72° containing very dry air. If more moisture is present, the temperature may drop to 65° without causing chilliness. Too much moisture is uncomfortable as well as too little, because if there is too much moisture in the air, evaporation cannot take place rapidly enough to keep the body cool. For this reason a sultry, muggy day is very op- pressive. As has been said, the average outdoor humidity is 70%. If, however, we attempted to make the air in our houses in winter time as moist as this, drops of water would gather on the walls and the windows would be completely covered with a thick coating of frost. On mild days this would melt and run down over walls and window sills. Humidity in dwelling houses and schoolhouses should run from 30% to 50% and not fall below 30%. How Humidity is Measured In order to keep the humidity of a building or room at the proper degree, there must be some means of measuring it. For this purpose three different instruments are used: the Measuring Humidity 81 SUA/G RSrCHROMETCR F/g. £8 hygrodeik, the hygrometer, and the sling psychrometer. Fig. 28. Of all these the sling psychrometer is the most satis- factory and accurate. Its action is very simple and easy to understand. It consists of two thermometers known as the wet bulb and dry bulb thermometers. The dry bulb ther- mometer is an ordinary thermometer such as is used for taking temperatures. The wet bulb thermometer, as its name in- dicates, has a piece of muslin or other porous material wrapped around the bulb and saturated with water. When the instru- ment is used it is whirled about with a rapid, even motion, thus causing a strong current of air to pass over the bulbs. We have already said that evaporation cools the surface from which it takes place. The water evaporating from the muslin surrounding the wet bulb cools it and causes the temperature to fall below that shown by the dry bulb thermometer. The drier the air, the more rapid will be the evaporation and the faster and farther the wet bulb thermometer will fall. It will finally come to rest at a point determined by the tempera- ture of the room and the moisture present in the air. The difference between the readings of the wet and dry bulb ther- mometers indicates a certain percentage of humidity. This may be caclulated, but the practical way is to read it from a table like the one shown as Fig. 26. For instance, suppose the dry bulb thermometer read 72° and the wet bulb 60°. To find the relative humidity we first subtract 60° from 72°. This gives 12° as the depression or difference between the wet 82 A Short Course for Janitor-Engineers and dry bulb thermometers. Now look down the column headed "air temperature" and find 72°. Run across to the right to the column headed 12. Opposite 72 and under 12 we find 49. This means that the relative humidity is 49%. As another example, take a dry bulb temperature of 68° and wet bulb temperature of 54°. The difference is 14°. Opposite 68 and under 14 we find 39. The relative humidity under these conditions is 39%. A sling psychrometer as described is not always avail- able. Very good results may be obtained with a 25-cent dairy thermometer in the following manner: Tie the ther- mometer securely to a string, 12 or 14 inches long, so that it may be swung like the psychrometer. See that the bulb is perfectly dry and take the room temperature at some point away from the wall and out of reach of warm or cold drafts. Note this temperature. Wrap a small piece of rag about the bulb and fasten with thread or string and saturate the rag with water. Take hold of the end of the string and walk about the room swinging the thermometer vigorously at the end of the string. (Be careful not to hit the wall or desks.) After swinging for 15 or 20 seconds, take a reading. Swing and read again. Do this until the temperature becomes stationary. The last reading is the wet bulb temperature. Subtract this from the dry bulb or room temperature previously noted and find the humidity from the table as before. Supplying Moisture to the Air As has been explained, moisture must be supplied to rooms artificially heated. Otherwise the relative humidity is too low for health and comfort. Let us see just how much moisture is necessary. Suppose we have a schoolhouse con- taining 200 pupils for whom there is an air supply of 30 cubic feet per minute per pupil. This means 30X200 = 6,000 cubic feet per minute and 60X6,000 = 360,000 cubic feet per hour. Putting Moisture into Air 83 Suppose the outdoor air has a temperature of 32° and a re- lative humidity of 70%. How much moisture must be added if the humidity in the room is to be 40% with a temperature of 70°? From the table on page 76 we find that air at 32° and saturated contains 0.301 pounds of moisture in 1,000 cubic feet. If the relative humidity is 70%, there are 0.301 X 0.70 = 0.210 pounds of moisture in 1,000 cubic feet. This air is brought into the building and heated to 70°. Air at 70° and saturated contains 1.14 pounds of moisture in 1,000 cubic feet. With 50% humidity it must contain 0.57 pounds. Since the incoming air contains 0.21 pounds, the amount to be added to every 1,000 cubic feet is 0.57-0.21=0.36 pounds. The amount of moisture to be supplied per minute for 6,000 cubic feet of air is 6X0.36 = 2.16 pounds. The amount required per hour is 2.16X60= 129.6 pounds, or about 15| gallons. In this calculation no allowance has been made for the expansion of the air when heated. The result shows clearly that a consid- erable quantity of moisture must be added to fresh outdoor air in order to keep the humidity at the proper point after heating to room temperature. This moisture can best be introduced in the form of steam. For this purpose take a piece of pipe five or six feet long and drill in it a number of \" holes 6 inches apart. Plug up or put a cap on the outer end and put a valve on the other end. Connect this with the boiler and allow steam to blow into the air supplied to the building. In case there is no direct air supply into which this moisture can be introduced, a small attachment known as an air moistener may be screwed on the radiators. This allows steam to escape quietly into the room. This can be used only on pressure systems. Air washers and humidifiers are now being used quite commonly. The incoming air is washed by passing through a spray or sheet of water and is humidified at the same time. In many cases the humidity and temperature are automatically con- trolled. Fig. 27 shows an air washer. 84 A Short Course for Janitor-Engineers In case a building is furnace heated and no steam is avail- able, moisture must be introduced in the form of water. Some furnaces are supplied with water pans and if they are kept hot enough to evaporate the water rapidly, sufficient moisture can be supplied. If these do not supply sufficient moisture, water may be introduced in the form of a spray in the warm air spaces. In this case a drip pan will be necessary to catch the excess water. Conclusions of the Chicago Commission on Ventilation on the Subject of Humidity and Proper Temperatures Resolved, That the relative humidity of a schoolroom, artificially heated, should not fall below 40 per cent. Resolved, That the temperature of a schoolroom should be kept as low as the comfort of its occupants will permit; and that the temperature may be kept down by increasing the relative humidity. Resolved, That in the proper ventilation of a school build- ing in cold weather, it is necessary to provide means for humidifying the air introduced into the buildings. (See note.) Resolved, That a constant temperature and a constant relative humidity are not conducive to the highest degree of comfort in a schoolroom. Resolved, That in the production of comfort for the occu- pants of a schoolroom, the maximum temperature should be associated with a minimum relative humidity, and the mini- mum temperature should be associated with a maximum re- lative humidity. Resolved, That in a school building artificially ventilated and heated, the comfort zone should be established in order that the engineer may properly operate the heating and venti- lating system. Putting Moisture into Air 85 Note: Relative humidity may be increased in a school room by means of properly muffled jets of steam introduced into the plenum or fan chambers from the boiler supply. Questions 1. Enginner A says that adding moisture to the air is not necessary because heating does not take any moisture out. There is just as much moisture indoors as outdoors, even in the winter time, and hence condi- tions are satisfactory. Do you agree? If not, explain how you differ. 2. Engineer B says that heating air "dries it out" and hence moisture must be added to replace that which is "dried out." Is he right? If not, explain. 3. Engineer C says that it is impossible for us to feel warmer in a humidified atmosphere, for everyone knows that we feel the cold more in a damp climate than in a dry one. Is he right, and if not, how do you ac- count for the fact which he states? 4. Professor B says that a dry atmosphere is good for pupils. If it isn't, why do people with lung trouble seek a dry western climate? Do you agree with him? 5. Engineer A says that with steam and warm air heat, we may need moisture, but not if hot water heat is used, because hot water heat is more moist. Is he right? 6. In a certain schoolhouse no frost gathers on the windows even in the coldest weather. What would you say about the condition of the air? 7. In a certain room the dry bulb temperature is 72° and the wet bulb 54 °. What is the percentage of humidity? 8. On a summer day the temperature registered 70 ° and the humidity was given as 87%. How many pounds of moisture were there in one thousand cubic feet of air? 9. Explain why moisture in the air contributes to our health and comfort. 10. Engineer A says that in testing for humidity that we should whirl the dry bulb thermometer about on the string and if we do the temperature will fall 5 or 6 degrees. Is he right? VIII SWEEPING, CLEANING AND SANITATION Sweeping and Cleaning Cleanliness is the great protection against disease. Sta- tistics show that tuberculosis and pneumonia are the two greatest causes of death in this country. The germs of both diseases are "air borne," that is, they are carried by the small particles of dust and dirt floating in the air and are breathed into the throat or lodge in the mouth and nose. Germs of measles, scarlet fever, diphtheria and other less important diseases are similarly carried. The janitor can do a great deal to eliminate these diseases by removing in a harmless way the dust and dirt which accumulate each day — dust and dirt which may many times be laden with disease germs. Sweeping Sweeping a room with a dry brush merely collects and removes the heavy dirt and stirs up the lighter dust to settle again in the same room. If a feather duster is used, the light dust is merely stirred up without removing it and it settles a second time. Dry sweeping in some states is forbidden by law, but where vacuum cleaning sj^stems are not installed the janitor is dependent on some form of sweeping and scrub- bing to keep his building clean. To keep down dust while sweeping, some kind of sweeping compound should be used. Snow was probably the first kind of sweeping compound em- ployed. Now there are various kinds obtainable, consisting chiefly of sawdust, sand, or pulverized woody fibre moistened with water or oil. This compound is sprinkled on the floor and, when pushed along with the broom, gathers and holds the dust. It is most useful on large, smooth, unobstructed 86 Sweeping, Cleaning and Sanitation 87 floors. In schoolrooms where the furniture is attached to the floor, the particles lodge in and around the legs of desks and accumulate in corners which are hard to reach. Commercial sweeping compounds are sometimes expensive. Home made ones are less expensive and often just as satisfactory. Saw- dust moistened with water or kerosene is the simplest and least expensive. Another way to make a sweeping compound is to dissolve a teacupful of boiled linseed oil in a gallon of gasoline and pour it onto all the sawdust that can absorb it. The gasoline evaporates at once and merely serves to spread the oil through the sawdust. Another compound is made as follows: 1 lb. sawdust, 1 lb. fine sand, \ pint water, \ pint kerosene. The sand and sawdust are mixed and the water and kerosene added. It is a good plan to wet the compounds with a liquid disinfectant diluted with water according to the strength of the disinfectant used, as an average, perhaps two or three tablespoonsful to a quart of water. Instead of sweeping compounds, floor dressings are some- times used composed of oil which will not dry hard upon the floor. Some claim that this oil imparts sufficient moisture to the dust to permit sweeping without raising a dust. The method has met with some success in schoolhouse work. One objection to it is, that the oil and dirt gradually accumulate and make a dirty floor. Another objection is that the dust, which may contain germs, is retained in the room and not removed from dangerous nearness to pupils. Another at- tempt to keep down dust has been to use oil brushes. These brushes differ from ordinary floor brushes in that they have on the top a pan or reservoir which keeps the bristles moist with kerosene or some other inexpensive oil. These brushes must be used carefully in order to avoid applying an unnecessary amount of oil to the floors, causing streaks. With proper use they are effective and are a long step in a hygienic direction. 88 A Short Course for Janitor-Engineers Special Methods of Cleaning Marble and tile floors should be mopped with hot suds and scrubbed with a soft hair brush to give a polish. A cement floor requires a hard brush, hot water and solvene powder or some other form of washing powder. For rough floors of hard or soft wood, use a scrubbing brush with soap and water and mop thoroughly. For varnished floors, use cold water and soap. Some varnishes will stand hot water. The following mixture used as a sweeping compound is said to take off stickiness and stains. Mix thoroughly a pint of soft soap with three quarts of water. Pour this mix- ture into two-thirds of a bucket of sweeping compound and stir until thoroughly absorbed. Give the floor a hard sweep- ing with this, using a soft bristle brush. If the floor is only slightly dirty it should be swept with a soft hair brush and dusted with an oiled mop. Painted walls and floors should be cleaned with hot water and soap. Toilet seats should be flushed thoroughly and washed with hot soda or soapy water, using a soft bristle brush. To take off stains of iron or other discoloration, muriatic acid is effective. This acid will not corrode porcelain or a vitrified surface. It must never be used even in a diluted form on any enameled surface. For the walls and floors of shower baths, use a hard brush and hot soapy suds. To clean dirty wash bowls use a cloth wet with gasoline. To clean brass, use two ounces of oxalic acid mixed with one quart of water. Rub thoroughly and remove with a damp cloth. Soap and water are as good as anything for cleaning ordinary door knobs. Clean windows are important because of their effect on the lighting. Experiments have shown that clean windows increase the light from 6% to 33%, depending on how dirty Cleaning Methods 89 they are in the first place. For cleaning either dry or liquid cleaners are good. Dry cleaners have one disadvantge, namely that when they are rubbed off, the dust flies about and settles on other things. Liquid cleaners consist of clear water or water mixed with washing soda, ammonia, kerosene or alcohol. Kerosene and alcohol may be used alone. The chief precau- tion necessary in using liquid cleaners is not to get so much liquid on the glass that it will run and cause streaks. To polish a window after dirt has been removed a chamois skin is best, as it leaves no lint. If kerosene and alcohol are used, un- diluted, they must be kept away from the framework of the sash, for they will soften paint and varnish. For this very reason, alcohol or turpentine is good to remove paint spots. Some recommend scraping with a dull knife or coin. If the spot must be removed by rubbing, a small cloth bag about the size of a 48-caliber bullet filled with powdered pumice stone is more effective and easier to use than the knife or coin. To polish varnished woodwork make a mixture of one- third turpentine and two-thirds boiled oil. Soak a cloth in this and wring out very dry. Rub the surface to be polished thoroughly and hard. An ordinary public building should be swept at least once a day. If dry sweeping must be done, all windows should be opened if the weather will permit, so as to carry off as much of the dust as possible and to give the room a thorough airing. For ordinary sweeping, a soft, mixed bristle brush of the 16" size is best. The handle should be frequently changed from one side to the other so as to wear the bristles evenly. To clean it, comb it out with a cleaner like a currycomb and wash with lukewarm (not hot) water. Do not wet the glue at the upper end of the bristles. After cleaning stand the brush upright on the handle where it will dry as quickly as possible. All cloths and brushes used in water should be well cleaned after using and quickly dried. Treated in this way, they will last much longer than if left neglected and dirty. For cleaning 90 A Short Course for Janitor-Engineers radiators, special soft bristle brushes are made. For sweeping cobwebs from walls and ceilings, use a long handled, soft bristle brush with bushy corners. To sweep dust from a smooth or papered wall, use a cloth on a straw broom. For a rough finish wall, use a straw broom without cloth and sweep vigorously. For dust rags, cheesecloth is the best material. When used, it should be lightly sprayed with linseed or kero- sene oil. This keeps dust from rising and flying about the room. Dust cloths should be thoroughly washed with hot water at frequent intervals in order to kill all disease germs. Be very careful not to use too much oil or desks and tables will be sticky. Sanitation To prevent the spread of disease where large numbers of children or adults are gathered, more than sweeping, dusting and scrubbing is necessary. Disease germs must be killed, for they cannot all be removed because they gather on walls and floors or are carried about from one place to another on the person or clothing or are blown about in the floating dust in spite of all we can do. These germs cannot live at all temperatures, but unfortunately the temperature of our dwelling houses and buildings is well suited for their multiplica- tion and growth. A very low temperature renders some germs inactive and may kill some. Heat will kill them, applied by baking, boiling or steaming. It is, however, manifestly im- possible to bake, boil or steam an entire building, hence some other means of killing germs must be resorted to. This is called disinfecting. A disinfectant is a germ killer or germi- cide. Disinfectants used may be gases, liquids or solids in the form of powders. One of the commonest gases for disinfecting is formed by burning sulphur and is known as sulphur dioxide. This is an excellent disinfectant and works best in moist, steamy air. Sulphur for this purpose can be best obtained in the form of a Health and Cleanliness 91 sulphur candle. This is lighted like an ordinary candle and left burning in the room. Sulphur dioxide gas is not very penetrat- ing and hence is not good for fumigating mattresses and bed- ding in order to kill bedbugs and other vermin. A large quan- tity of sulphur must be burned to make the process thorough because the gas must be very strong in order to kill the germs and they must remain in it for some time. It does not kill quickly. One disadvantage in using sulphur dioxide is the fact that it attacks metals. Polished brass, silver, nickel or aluminum turn black when exposed to it. It also has a bleach- ing action on colors. Formaldehyde gas is another common disinfectant. This is not poisonous, strictly speaking, and does not attack metals or bleach out colors. It has a very irritating effect on the eyes, nose and throat. The gas is formed by heating a liquid solu- tion of formaldehyde in water, thus driving off the gas. Some- times the solution is simply sprayed about the room on floors and walls and allowed to evaporate. This is not very effective. Hydrocyanic gas (one of the most deadly poisons known) is sometimes used for fumigating. This gas will, in a short time, kill every living thing with which it comes in contact. It is, therefore, especially valuable in killing vermin. One or two good breaths of it are fatal to a human being. It should never be used except under the direction of a medical expert or health officer. When disinfecting a room by gas, be sure that all openings, such as doors, windows and air registers, are tightly closed. Drawers and cases should be opened and books, clothing, curtains and portieres spread out so that the gas can get all through them. After disinfecting, open and thoroughly air out the room. Carbolic acid, sometimes called "phenol," is the most common and one of the oldest liquid disinfectants used. It is a deadly poision and hence must be handled with great caution. There are many commercial germicides sold under different names. These are generally marked with what is 92 A Short Course for Janitor-Engineers known as the "phenol coefficient." This is a number which compares their strength with that of carbolic acid. For instance, if a germicide has a phenol coefficient of ten it means that it is ten times as strong as carbolic acid. Some states re- quire that all germicides be marked in this way. Bichloride of mercury, commonly called corrosive sublimate, is another deadly poison often used in solution as a liquid disinfectant. Solid disinfectants like choloride of lime can only be sprinkled about and hence are not as effective as liquids and gases. Whitewash has a slight disinfecting action and is good for cellar and basement walls, where it will help the lighting as well as disinfect. Health authorities usually require that school buildings be disinfected whenever there is an epidemic of any infectious or contagious disease. If any pupil has been found to have a disease, the room should be disinfected at once. Owing to the prevalence of chicken pox, measles, scarlet fever, whooping cough, etc., school buildings and rooms should be systematical- ly disinfected at regular and frequent intervals, and be kept thoroughly clean and sanitary at all times. Disease germs thrive in dirty quarters. This is so important that many states prescribe that floors, desks, wainscoting, stair rails, door knobs, window sills and blackboards be wiped at intervals with a disinfecting solution. One state at least requires this to be done daily. Toilet rooms are the most difficult parts of a building to keep clean and sanitary. The general principles of plumbing should be understood by every man in charge of public buildings. These can only be suggested here. Fixtures are arranged with water sealed traps so that no gases can get back from the pipes to the rooms. Piping systems are "vented," that is, open at the roof, and have an air inlet lo- cated on the ground near the outlet of the system from the building. This allows free circulation of air through the pipes and removes all gases that form. It is very important Disinfectants and Their Use 93 that the system be absolutely sealed by traps at every possible outlet into the building. Toilet fixtures should be cleaned daily with some disinfecting solution that will kill any and all germs. The disinfectant can be placed in the soap and water used for cleansing. Deodorants are sometimes used. A deodorant simply absorbs or covers up objectionable odors. It should not be confused with a disinfectant. A deodorant does not necessarily destroy germs and hence is not always a preventive of disease. RULES AND REGULATIONS FOR CLEANING AND CARE OF SCHOOL BUILDINGS AND GROUNDS (Used by courtesy of Geo. F. Womrath, Business Supt. of School Board, Minneapolis, Minn.) 1. Each head janitor shall be responsible for the cleanly condition of his building, and he must be observant of dirt, dust and bad odors and see that same are removed without having special attention constantly called thereto. 2. In order that the school building may be properly cleaned, janitors are to be permitted by the principal to begin their schoolroom cleaning not later than twenty minutes after the close of the afternoon session. 3. Under no circumstances is there to be any sweeping done while the schools are in session with exception of corri- dors and stairs, except by permission of the principal of the school. 4. Under no circumstances shall coal oil or kerosene be used for cleaning purposes. 5. When no night school is held, each school building must be carefully and thoroughly swept each school day, the work to be commenced twenty minutes after the close of the last session and to include the entire building, together with outside closets, if any. 6. In buildings where night school is held, the janitor shall pick up after the close of the day session all waste paper and rubbish from the floors and furniture of the rooms which are used for night school, and shall in other ways put the school in a neat and clean condition before the opening of the night session, and shall have the building properly lighted and heated one-half hour before the opening of the night session. 7. In buildings where evening school sessions are held, all classrooms and other floor space used for night school 94 Rules for Building Care 95 must be thoroughly swept, commencing fifteen minutes after the close of night session. 8. Assembly halls must be kept in as neat condition as classrooms. 9. All woodwork, moldings, window sills, wainscoting, handrails, radiators, pianos, pictures, casts, shelves, chalk troughs, principals' desks, teachers' tables, pupils' seats and desks, chairs, furniture and apparatus of every description must be thoroughly dusted each school day. 10. Every school building must be thoroughly cleaned three times each year as follows: During the summer, Christmas and Easter vacations, the engineers and janitors shall thoroughly brush all the walls, ceilings and window shades of their respective buildings be- fore proceeding to wash the woodwork, which shall include oil painted walls, dadoes, baseboards, wainscoting, doors, frames, sash and all painted and varnished woodwork. They shall thoroughly wash with water the glass in all windows, transoms and furniture, and dust all picture moulding and the fronts and backs of all pictures. The floors of all entries, halls, passages, stairways, corridors, and all rooms occupied for school purposes and stair landings shall then first be well scrubbed with scrub brushes and then mopped. 11. Chairs and desks shall be washed three times a year and at same time the general cleaning is done. 12. Chairs and desks which have been occupied by pupils who have contracted a contagious disease shall at once be thoroughly washed with a disinfectant to be furnished by the Supply Department. 13. Kindergarten rooms must be thoroughly swept and dusted after the morning session as well as after the afternoon session. 14. Kindergarten floors must be scrubbed at least once each week and must be wiped off with a damp mop or rag each morning before school opens. 96 A Short Course for Janitor-Engineers 15. Manual training rooms shall be thoroughly swept and dusted each day after the rooms are used and all shavings, sawdust and rubbish must be removed. 16. The cooking room, including pantry and dining room, shall be scrubbed once every week and shall be swept and dusted, and the garbage bucket emptied and cleaned each day that the room is used. 17. Extra precautions shall be taken in cleaning around the radiators, and to see that rags, paper or any other material of an inflammable nature does not come in contact with the radiators by being on or behind them. 18. In buildings heated by hot air. furnaces, and where floor registers are used, the register boxes must be cleaned at least once a week, and oftener if necessary. 19. Doors and door-knobs of schoolrooms and hand- rails and banisters of stairs shall be washed at least twice each month with a disinfectant to be furnished by the Supply Department. 20. Janitors shall keep gas and electric fixtures clean, removing rust and dirt from interior of all X-Ray reflectors at least once each month. 21. All sidewalks, pavements and yards shall be swept as often as is required to keep them in good condition and at least twice each week. 22. All outhouses, areas, light-courts, sidewalks, gutters, playgrounds, grass plats, lawns, store rooms, boiler rooms, cellars, attics, roofs, etc., shall be kept in a neat and tidy con- dition free from all rubbish, stones, litter, pieces of paper and other waste matter of every description, and clean and in order at all times, and the janitor is to allow no accumulation of paper, wood, ashes or refuse of any kind therein or thereon, and a tour of inspection for the observance of these conditions shall be made at least once every day. 23. The urinal troughs and the floors around them shall be flushed with a hose after every recess period. Rules for Building Core 97 24. All closet seats shall be kept dry and bowls flushed during school sessions. 25. The urinal troughs, seats of the closets, fixtures and floors shall be washed and disinfected every day after school sessions, and tanks in connection with water closets must be kept free from mud and other sediment. 26. The water closet bowls and urinals and all par- titions to urinals and backs of same shall be cleaned at least once each week with a disinfectant to be furnished by the Supply Department. 27. At all times a sufficient supply of toilet paper shall be kept in each toilet room and towels wherever there is a lavatory. 28. All toilet paper and towel racks out of order must be reported at once. 29. The water and gas shall be turned off at the supply mains at the close of school each day and on again just before the opening of school in the morning. Every precaution shall be taken in cold weather to prevent all pipes and other ap- paratus from freezing and to see that all plumbing fixtures are drained during freezing weather. All damage resulting from freezing of plumbing, pipes, apparatus or other fix- tures will be charged to the janitor. 30. In extremely cold weather, after the water has been shut off from the building, drain the toilet and urinal tanks, open all faucets, and then fill toilet bowls and traps on fixtures with a solution of salt water. 31. All slop sinks, wash bowls and other fixtures through- out the building shall be cleaned every school day. 32. Janitors shall not clean nor allow any of their as- sistants^to^clean the windows of their school buildings on the outside while standing on the outside window sills or ledges of the school buildings without the use of a window platform or harness furnished for that purpose. 33. After snowstorms, a path is to be cleared on all 98 A Short Course for Janitor-Engineers walks and steps in and about the school premises before 8 A. M. so as to provide access to the several entrances to the buildings and to outhouses. 34. All snow and ice must be removed from the steps, fire escapes, entrances and inside and outside walks of the school premises before 12 o'clock noon of the same day that the storm occurs. 35. Janitors shall sprinkle sand or ashes or salt upon sidewalks when they are in a slippery condition; a supply of sand, ashes or salt for this purpose to be kept on hand. 36. Janitors shall keep fire escapes clear and clean at all times. 37. During the winter months the boiler room, engine room and inside of all fresh air shafts are to be whitewashed. 38. Special attention is to be given to the flow of water in urinals, drinking fountains, etc., and all leaks promptly stopped, and the water for urinals, drinking fountains, etc., turned off as soon as school is dismissed. 39. The electric current used for lighting, power or stereopticon shall be shut off from the building at the service switch each night before leaving the building. THE JANITOR'S CATECHISM 1. Do you practice damp sweeping? 2. Do you use a moist or oiled cloth for wiping up dust? .3. Do you ever use a feather duster? 4. Do you use a disinfectant on the floors? 5. Do you clean the desks with a disinfectant? 6. Do you disinfect the school books when necessary? 7. Is your ventilating system in good working order? 8. Are some of the windows always opened if the fan is not running? 9. If there is no mechanical system of ventilation, are some of the windows always open at top and bottom? 10. Are window boards placed under the lower sash to prevent draft? 11. Are all windows thrown open at recess? 12. Have the tops of the desks been redressed within two years? 13. If any room is heated by a stove is there a jacket around the stove? Is there any special arrangement for getting air in and out of the room? 14. If the building is furnace heated, is there an outdoor air supply and is the inlet clean and unobstructed? 15. Is there some means provided for moistening the air? 16. Is the fresh air inlet removed from toilets or other sources of contamination? 17. Are the schoolrooms free from unpleasant odors at all times? 18. Are erasers cleaned every day out of doors? 19. Are floors oiled or otherwise treated to keep down dust? 20. Do you keep your temperatures even? 21. Do you keep the room temperatures under 70° and over 60°? Halls 22. Do you keep the halls of your building clean? 23. Are the halls well heated? 24. Are the halls well ventilated? 25. Are the halls free from obstructions? Basement 26. Are the floors clean and dry? 27. Are the floors made of cement? 28. Are wash basins and sinks clean? 99 100 A Short Course for Janitor-Engineers 29. Are toilets clean and well ventilated? 30. Is the air wholesome? 31. Are toilets well shut off from air intakes? School Environment 32. Is the ground well drained? 33. Are tin cans and other receptacles in which water might col- lect kept picked up? 34. Are other breeding places of mosquitoes destroyed? 35. Is garbage of all kinds properly destroyed? 36. Is manure and other refuse hauled away as fast as it collects? 37. Are the garbage cans in the neighborhood kept covered? 38. Do you clearly understand that all such refuse as the above furnishes a breeding place for flies and that flies are dangerous carriers of disease? 39. Is the drinking water clean? 40. Is there any chance for the drinking water to be contaminated by sewage? 41. Are there relatively few flies about the building? 42. Are the vacant lots nearby kept clean? Brief List of Valuable Books for Janitor-Engineers School Janitors, Mothers and Health, Putnam. American Academy of Medicine Press, Easton, Pa. Report of the Chicago Commission on Ventilation. Department of Health, Chicago, Illinois. Standard Practical Plumbing, Starbuck. Norman W. Henley Publishing Co., New York City. Johnson's Handy Manual of Plumbing, Heating and Ventilating. Domestic Engineering, Chicago, 111. The Sanitary Sewerage of Buildings, Ainge. Domestic Engineering, Chicago, 111. The Warm Air Furnace Handbook. Peck Williamson Co., Cincinnati, Ohio. Heating and Ventilation. B. F. Sturtevant Co., Boston, Mass. Fuel Economy in the Operation of Hand-Fired Power Plants. Bulletin Engineering Experiment Station, University of Illinois, Urbana, Illinois. 101 INDEX Air circulation for radiators, 56 Air distribution, 62 Air, good and bad, 59 Air, introducing moisture into, 82, 8.3 Air space requirements, 61 Air supply requirements, 62 Air temperature, 8 Air values, 52 Air washers, 83 Air, water carrying capacity, 76 Alternate firing method, 39 Analysis of coals, 27 Anthracite coal, 26, 27 Aspiration method of ventilation, 63 Banking fire, 45 Bins, calculation of size, 29 Bituminous coal, 26, 27 Boiler, boiling out, 48 Boiler, laying up, 50 Boiler, operation of, 47 Boiler scale, removal, 49 Boiler, washing of, 48 Book list for janitor-engineers, 101 British Thermal Unit, 10 By-pass damper, 67 Calculating sizes of coal bins, 29 Carbon dioxide, 32 Catechism for janitors, 99 Centigrade thermometer, 7; scale, 9 Chicago Ventilating Commission's Conclusions on Heating and Ventilation, 72; Conclusions on Humidity and Temperature, 84 Cleaning methods, 88 Clinkers, prevention of, 45 Coal, analysis of, 27 Coal and combustion, 24 Coal, composition, 24 103 104 Index — Continued Coal, names and sizes, 29 Coal storage, 30 Coke, 29 Coking method of firing, 40 Combustion, 30 Combustion of coal, 33 Conduction of heat, 16 Convection of heat, 16 Deodorants, 93 Diaphragm valves, 55 Direct and indirect heating systems, 55 Direct fan system, 65 Direct-indirect fan system, 67 Disinfectants, 90 Disinfecting methods, 91 Disinfection, prescribed by health authorities, 92 Draft, control of, 43 Dusting, 90 Duties of janitors, 7 Effects of heat, 12 Effects of high and low humidity, 79 Fahrenheit thermometer, 7; scale, 9 Fan system, 65 Fan systems, operation, 70 Fire, banking of, 45 Fire, how to maintain, 41 Firing, 35 Firing methods, 39 Firing, special methods and appliances, 41 Fixed carbon, 25 Float valve, 53 Furnace and combustion, 32 Heat, effects of, 12 Heat, effect on water, 13 Heat measurement, 9, 10 Heat, rate of travel, 20 Heat, theory of, 7 Heat travel, circumstances affecting, 17 Heat, travel of, 14 Index — Continued 105 Heat, units in elements, 33 Heating coils, 67 Heating plant, 47 Heating plant, definitions, 51 Heating systems, 50 Heating value of coal, 27 Humidity, 74 Humidity, effects of, 79 Humidity, measuring of, 80 Humidity, relation to temperature, 77 Humidity table, 78 Indirect fan system, 65 Janitor, duties of, 7 Janitor's catechism, 99 Latent and sensible heat, 20 Laying up a boiler, 50 Measuring humidity, 80 Mechanical ventilation, 63 Methods of firing, 39 Mixing dampers, 67 Moisture content of air at varying temperatures, 76 Moisture, introducing in air, 82, 83 Names and sizes of coal, 29 Natural and aspiration systems, 68 Natural ventilation, 63, 69 Plenum room, 67 Radiation, 16, 19 Radiators, placing of, 55 Rate of heat travel, 20 Recirculation of air at night, 57 Relative and absolute humidity, 75 Room temperature, 8 Rules and regulations for cleaning and care of buildings and grounds, 94 Rules for building care, 97 Sanitation, 90 Scale, boiler, 49 1 OG / ndex — Concluded Semi-bituminous coal, 20, 27 Sling psychrometer, 81, 82 Smoke, causes, 37 Smoke prevention, 35 Specific heat tables, 1 1 Spreading method of firing, 39 Steam heating, 52 Steam jets, 68 Steam table, 21 Storage of coal, rules for, 30 Sulphur dioxide, 32 Sweeping, 86 Sweeping and cleaning, 80 Sweeping compound, 88 Temperature, requirements, 03 Temperature tables, 9 Tempering coils, 67 Thermometer, dry bulb, 81; wet bulb, 81 Thermometers, 7 Thermostatic value, 53 Thermostats, 55 Vacuum and vapor systems, 53 Ventilation systems, 63 Warm air heating systems, 56 Washing boiler, 48 Water, moisture, 84 Water, heating qualities, 13 Water pans, 84 Water pounding, 53 Winter care of school buildings, 98 Woodwork polish, 89