Document npLrJynN7e6dEY8Qy1d5rbVmR

ofAmerican Society Heating and Ventilating Engineers Guide, 1924-25 TABLE 51. HEIGHT OF.STACK FOR AVERAGE INSTALLATIONS (Sea Level)--Continued Diameter of Chimney in Inches for Horizontal Return Tubular Boilers Height-of Stack in Feet--Foa Sea Level and 60 deg. eahe. Outside Temp. Assumed Friction Loss IN Stack 0.1 in. per 100 ft. Nominal H. P. IS 20 25 30 35 40 50 60 75 90 100 115 125 150 175 200 210 225 250 100% Rating 13 14 16 17 18 19 20 21 23 25 26 27 28 ' 30 32 33 34 35 36 150% Rating 14 16 18 19 20 21 23 24 26 28 29 31 32 34 36 38 38 40 41 200% Rating 17 18 20 21 22 23 25 27 29 31 33 34 35 38 40 43 44 45 47 Draft at Base of Stack 0.12 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 100% Rating 21 26 35 43 52 60 69 78 86 95 104 112 1 150% Rating 22 28 37 46 56 65 74 84 93 102 112 121 200% Rating 25 30 41 51 61 71 81 91 101 111 122 132 DATA ON WHICH TABLES ARE BASED Rating............ Efficiency___ CO,................ 100% 150% 200% 65% 65% 63% 8% 9% 10% Stack Temp, deg. fahr--.............. 450 Lbs. of Gas.................. 85 500 77 550 73 AVERAGE FRICTION LOSS THROUGH BOILERS Per Cent Rating ......... Loss Ins., Water._.......... 100 0.1to0.3 150 0.2to0.6 200 0.3to0.9 250 0.5 to 1.4 300 0.7 to 1.9 FForirctFiounrnlaocses tDhrraofut.g--hAbloloilewr 0v.a1r5iefsoarcfcoorcrdeidngdrtaofct.onFstorrucNtiaotnu.ral Draft 0.35 in. or higher shoutd be used depFeonrdBinrgreuephoinng rFartiectoiof-ncoLmosbsu.--stAiolnloawu0d.0fu5eiln.usfoedr.each right angle bend and 0.1 in. per 100 ft. of length. Cross sectional area should be 20 per cent larger than that of stack. HEIGHT OF STACK IN FEET - - - - -- - -- Inn tt Total Draft Required In. for Furnace Boiler and Breeching 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.8 Assumed Flue Gas Temp.. Per Cent of Boiler Bating 100 56 74 93 111 130 148 500 60 150 200 69 86 81 103 97 120 113 138 129 155 145 172 161 190 177 194 209 226 1 550 1 600 250 108 123 139 154 170 185 200 216 231 650 300 -- -- -- 132 147 162 176 191 206 221 236 . 265 700 American Society of Heating and Ventilating Engineers Guide, 1924-25 ' CORRECTION FOR ALTITUDE Height Above Sea Level (Ft.) Ratio Increase in Diameter Ratio Increase in Height 0 1,000 2,000 4,000 6,000 8,000 10,000 1.000 1.015 1.030 1.063 1.096 1.130 1.165 1.000 1.046 1.097 1.205 1.321 1.456 1.612 An approximate rule often applied to chimneys over 64 ft. high, as regards rate of combustion is: Rate Combustion for Hard Coal = i 3-Si Rate Combustion for Soft. Coal = 2 Where H = height of chimney in feet. In the absence of a chimney size formula based on research data, the formula given in Kent's Hand Book is about the best available. R = 333 E where R = steam rated capacity of boiler in square feet. E = effective area of stack in square feet which should not extend within 2 in. of stack walls. % H = square root of height in feet measured from center of breeching connection ' to stack. The height of stacks less than 65 ft. should not be less than 30 times the diameter or width of stack. The rate of combustion in heating boilers ranges from 5 lb. to over 20 lb. of coal per square foot of grate per hour, according to the height of the stack. Large heating boilers are being attached to stacks 100 to 300 ft. high. Small round boilers require from 0.1 to 0.2 in. of draft at the smoke outlet, according to the number of intermediate sections placed between the firepot and dome sections. Medium size boilers require from 0.15 to about 0.5 in. of draft. Smokeless boilers require from 0.4 to 1.0 in. of draft to develop their rated capacity. Such conditions as nature of fuel condition of firebed, amount of excess air used and condition of the flue travel very materially increase or decrease the draft required to develop the rated capacity of any boiler. Small house heating boilers should be rated on a 10-hr. hard coal basis. The larger size boilers using hard coal and having a grate over 40 in. wide are rated on a 4 to 6-hr. hard coal basis. AH boilers burning soft coal are rated on an hourly basis because of the tendency of soft coai to burn holes through the firebed in a- relatively short time after firing. The largest size of boilers aire rated on an. hourly basis since a firemaj in constant attendance. 61 St