Document xz4D4JmQxY4e4EzmaKDLx7ewJ

American Society of Heating and Ventilating Engineers Guide, 1929 Table 5. Available Draft for 100 Ft. Steel Stacks of Different Diameters* (Based on a stack temperature of 500 deg. fahr.** and 100 lb. of gas per horsepower. . For other heights of stack, multiply draft by height s- 100) Diameter or Stack, in Inches 36 54 60 66 M l 96 108 120 200 0.55 400 0.21 600 800 1000 1200 1600 2000 2500 3000 3500 4000 4500 0.62 0.46 0.19 0.56 0.42 0.23 0.61 0.53 0.43 0.29 0.59 0.52 0.45 0.35 0.58 0.53 0.47 0.31 0.61 0.58 0.54 0.43 0.63 0.61 0.63 0.61 0.56 0.50 0.41 0.64 0.62 0.59 0.54 0.48 0.40 0.65 0.65 0.63 0.64 0.60 0.61 0.63 0.56 0.59 0.61 0.52 0.56 0.58 0.48 0.52 0.56 0.43 0.49 0.53 0.44 0.49 0.63 0.64 0.62 0.64 0.60 0.62 0.58 0.61 0.56 0.60 5000 DFaotraoftrhoemr sMtaackrktse'mMpeecrahtaunreicsaal dEdngoirndeeerdsuHctabnedfbooreokm. ultiplying by height -100. a as follows: For 750 deg. fahr. add 0.17 in. For 700 deg. fahr. add 0.14 in. For 650 deg. fahr. add 0.11 in. For 600 deg. fahr. add 0.08 in. For 550 deg. fahr. add 0.04 in. For 450 deg. fahr. deduct 0.04 in. For 400 deg. fahr. deduct 0.09 in. For 350 deg. fahr. deduct 0.14 in* Table 6. Stack Sizes by Kent's Formula (Assuming 5 lb. of coal per horsepower per hour) . Amu I 8a Ft. 50 | 60 | 33 36 39 42 48 54 .60 66 72 78 84 5.94 106 115 7.07 129 141 8.30 155 169 9.62 183 200 12.57 246 269 15.90 318 348 19.64 400 437 23.76 490 537 28.27 591 646 33.18 700- 766 38.48 818 896 90 44.18 96 50.27 102 56.75 108 63.62 114 70.88 120 78.54 126 86.59 132 95.03 144 113.10 156 132.73 168 153.94 too Commercial HOESEroWEB 1893 2008 2116 2167 2298 2423 2459 2609 2750 2770 2939 3098 3100 3288 3466 3448 3657 3855 3814 4046 4265 4200 4455 4696 5026 5331 5618 5925 6285 6624 6899 7318 7713 30 32 35 38 43 48 54 59 64 70 75 80 86 91 98 101 107 112 117 128 138 150 33 36 39 42 48 54 60 66 72 78 84 90 96 102 108 114' 120 126 132 144 156 168 154 Chapter VI--Chimneys Loss of draft through the fuel bed or the force of draft necessary to burn different grades and sizes of coal at different rates of combustion may be taken from Fig. 1, p. 163 of Chapter VII on Mechanical Draft. Table 7. Stack Sizes for On. Fuel*i Stack Duustsb Inches 33 36 39 42 48 54 60 66 72 84 96 108 120 80 161 208 251 295 399 519 657 813 980 1373 1833 2367 3060 Height in Fkbt Above Boiler Room Floor 90 206 253 303 359 486 634 800 993 1206 1587 2260 2920 3660 100 233 295 343 403 551 720 913 1133 1373 1933 . 2587 3347 4207 . 120 270 331 399 474 645 847 1073 1333 1620 2293 3087 4000: 5040 140 306 363 488 521 713 , 933 1193 1480 1807 2560 3453 4483 5660 160 315 387 467 557 760 1000 1280 1593 1940 2767 3740 4867 6160 Data from Marks' Mechanical Engineers Handbook. Figures represent nominal rated horsepower; sizes as given are good-for 50'per cent overloads. Based on centrally located stacks, short direct flues and ordinary operating efficiencies. Correction for altitude may be made according to Table 8. Table 8. Correction Factors for Altitude Height Above Sea Level Feet 0 1,000 2,000 4,000 6,000 8,000 10,000 Ratio Increase m Diameter 1.000 1.015 1.030 1.063 1.096 . 1.130 1.165 Ratio Incbeasb in Height 1.000 1.079 1.164 1.356 1.580 1.841 2.144 CHIMNEYS FOR. GAS APPLIANCES The burning of gas- differs from the burning of coal in that the force which supplies the air for combustion of- the .gas comes largely from the pressure of the gas in the supply pipe, whereas air is supplied to a bed of burning coal by the force of the chimney draft. If, with a coal-burning boiler, the draft is poor, or if the chimney is stopped, the fire is smothered and the combustion rate reduced. Such a condition- on a gas-boiler or furnace would interfere with the combustion of the gas, but the gas would continue to pass to the burners and the resulting incomplete com bustion would produce a dangerous condition. In order to prevent incomplete combustion from insufficient draft, all gas-fired boilers and furnaces should have a back draft diverter in the flue connection to the chimney. 155