Table 51 --DIFFERENCE IN WEIGHT OF TWO COLUMNS OF WATER, EACH I FOOT HIGH AT VARIOUS TEMPERATURES; ASSUMED ACTUAL TEMPERATURES FROM 170° то 199° F. Table 52.-LENGTH OF 4-INCH PIPE TO HEAT 1000 CUBIC FEET OF AIR PER MINUTE; TEMPERATURE OF THE PIPE 200° F. Temperature of EXTERNAL AIR. TEMPERATURE AT WHICH THE ROOM IS REQUIRED TO BE KEPT. 135 159 Fahrenheit. 45° 50° 55° 60° 65° 70° 75° 80° 80° 85° 85° 90° 10° 126 Feet. Feet. Feet. Feet. Feet. Feet. Feet. Feet. Feet. Feet. 200 229 259 292 328 367 409 142 166 192 220 251 283 318 357 399 184 212 242 274 105 18° 127 151 176 20 309 347 | 388 204 233 265 300 337 378 168 195 225 135 160 187 216 105 128 152 179 199 69 90 112 136 162 89 112 80 72 42 64 279 317 202 234 269 307 137 164 193 225 259 296 129 155 184 215 249 286 I 20 147 175 206 239 276 112 138 166 196 230 266 104 129 157 187 220 255 95 121 148 178 210 245 87 112 139 168 200 235 79 103 130 229 262 298 337 159 190 225 181 214 77 103 131 * Freezing point. To find the length in feet of iron pipe required for heating the air in a building. Rule: Multiply the volume of air in cubic feet, to be warmed per minute, by the difference in temperature in the room, and the external temperature, and multiply by 1'12 for 2-inch pipes, by 75 for 3-inch pipes. by 56 for 4-inch pipes, and divide the product by the difference of the internal temperature and that of the pipes. Table 53-LENGTH OF 4-INCH PIPE REQUIRED TO WARM VARIOUS BUILDINGS. (Divide the cubic contents of the room in feet, by one of the following 3-inch pipes require to be one-third longer than 4-inch pipes, to heat the same number of cubic feet; and 2-inch pipes require to be double the length of 4-inch pipes, to heat the same number of cubic feet. Table 54.-COOLING OF IRON PIPES. Temperature of room, 67°; maximum temperature of thermometer, 152°. Table 55.-RATE OF COOLING BY RADIATION FOR THE SAME BODY. AT DIFFERENT TEMPERATURES. Table 56.-SHOWING THE QUANTITY OF COAL USED PER HOUR, TO HEAT 100 FEET IN LENGTH OF PIPE OF DIFFERENT SIZES. DIFFERENCE BETWEEN THE TEMPERATURE OF THE PIPE AND THE ROOM 150 145 140 135 130 125 120 115 110 105 100 95 90 | 85 | 80 lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. 47 45 4 4 4 2 41 3'9 37 36 34 32 31 29 2·8 2·6 2·5 3.8 34 33 31 30 29 2.8 2.7 2.5 24 23 22 21 20 18 23 22 22 21 20 19 18 18 17 16 15 14 14 13 12 I'I I'I I'I IO 1'0 9 9 9 8 8 7 7 7 6 6 When pipes are laid in trenches covered with grating the loss of heat amounts to about 10 per cent., which passes into the ground. Boiler Power.-For heating purposes by hot water, the saddle boiler gives good results. One square foot of boiler surface exposed to the direct. action of the fire, or three square feet of flue surface, will heat 40 feet of 4-inch pipe. The Quantity of Air to be Warmed per Minute is from 4 to 5 cubic feet for each person, with the addition of 1 cubic feet for each square foot of glass in habitable rooms; for conservatories and hot-houses the quantity of air to be warmed is 1 cubic feet per square foot of glass per minute; as iron frames and sashes radiate as much heat as glass, their surfaces are to be measured with the glass. For wood frames deduct from the gross area of surface. Heating Rooms by Steam at 212° F.-A 1-horse-power boiler is sufficient for 48,000 cubic feet of space. To heat a room to 60° F. the length of steam-pipe may be found by the following rule. To find the length in feet of steam-pipe: Multiply the volume of air in cubic feet, to be warmed per minute, by the difference of temperature in the room and the external temperature, and divide the product by 304 for 4-inch pipe, or by 228 for 3-inch pipe, by 152 for 2-inch pipes, and by 76 for 1-inch pipe. Expansion of Steam and Hot-water Pipes.-An expansion-joint should be added to long lengths of steam-pipes, to allow for their increase of length from expansion. The quantity of expansion can be found thus: Multiply the coefficient of expansion given in Table 48 by the difference in temperature of the outside and inside of the pipe, which result multiply by the length of pipe. Thus with a cast-iron steam-pipe 160 feet long, with the temperature of the air at 60° and the steam at 324° F., the difference of temperature will be 324-60 = 264°, and the increase in length due to expansion will be '0000065 rate of expansion x 264° temperature × 160 feet x 12 inches = 3294 inches. VENTILATION, &c. The Amount of Air required for the proper ventilation of apartments is from 4 to 5 cubic feet of air per head per minute in winter, and from 6 to 10 cubic feet in summer. A man makes about 17 respirations per minute each of 40 cubic inches, or 17 X 40 X 60 1728 = 236 cubic feet per hour; for respiration and transpiration a man requires 215 cubic feet of air per hour. A man generates about 290 units of heat per hour, 100 units of which go in the formation of vapour, and the remaining 190 units are dissipated by radiation to the surrounding objects and contact with cold. air. An ordinary gas burner consumes about 5 feet of gas per hour, and requires for combustion 12 cubic feet of air per cubic foot of gas, or 60 cubic feet per hour for each gas burner; each cubic foot of gas burned emits about 690 units of heat; each pound of candles or oil burnt requires 160 cubic feet of air for combustion, and emits 16,000 units of heat. The Quantity of Air required for the proper ventilation of various buildings is given below: For apartments with healthy occupants For apartments with sick occupants For prisons and workhouses For churches and assembly rooms Cubic feet per head per hour. 300 . 1200 350 550 2200 4500 The Space provided for each Bed in the wards of ordinary hospitals, should not be less than 1800 cubit feet, and in hospitals for infectious diseases not less than 2500 cubic feet. The space provided in dwelling houses, should not be less than 300 cubic feet for each person in a room, whether children or adults, as children require as much space as adults. Ventilation of Mines.-The quantity of air required for the health of each person underground is 100 cubic feet per minute; in addition to this, in fiery mines air is required in the proportion of 30 cubic feet for each cubic foot per minute of fire damp given off. Space Required for Animals. A pig requires 10 square feet of floor space; a sheep, 15; a bullock, 70; a cow, 100; and a horse, 120 square feet of floor space. The cubical space should equal 13 times the given floor space for a horse, and 10 times the given floor space for each of the other animals above mentioned. Furnace-ventilation. The power obtained is measured by the difference between the weights of air in the downcast and upcast shafts. The length of column in the downcast shaft, which would be equal in weight to the difference of the weight of air in the two shafts, is called the motive column. To find the motive column.-Rule: From the temperature of the upcast shaft, subtract the temperature of the downcast shaft, and divide the remainder by the product of the temperature of the upcast multiplied by 459; multiply this quotient by the depth in feet of the downcast shaft. To find the weight in lbs. of a cubic foot of air.-Divide the number 519 by the product of 459 multiplied by the temperature, and multiply the quotient by 0765546. By multiplying the weight of one cubic foot of the air in the shaft by the cubic area of the shaft, the total weight of the air in the shaft is obtained. Weight of one cubic foot of pure Air under a pressure of one atmosphere. Atmospheric Air is increased in volume by elevation of temperature, as follows. 42° 50° 32° Fahr., volume = 1'000 At 180° Fahr., volume = 1°310 |