Document zQwwYKMx87zMQQRGoLXGBZ076

of and 1937American Society Heating Ventilating Engineers Guide, Fig. 1. Chart for Estimating Dollar Value of Heat Loss from Bare Iron Pipes. (See Table l)a This chart is based on 100 linear feet per 1000 hours. For fractions or multiples of these factors, multiply by proper percentage. ` heat equivalent to more than a ton of coal per year shows the necessity for insulating such surfaces. STEAM AND HOT WATER LINES The conductivities of various materials used for insulating steam and hot water pipes are given in Table 5. . In this table the conductivities are given as functions of the mean temperatures or the mean of the inner and 670 36--Chapter Insulation of Piping * Table 1. Heat Losses from Horizontal Bare Iron Pipes Expressed in Btu per linear foot per degree Fahrenheit difference in temperature between the pipe and surrounding still air at 70 F Nominal Pipe Sice. (Inches) :m H l .1M 2 2H 3 3A 4 4H 5 6. 8 10 12 120 F Hot Water 150 F 180 F 210 F 227.1 F (5 Lb) Temperatube Difference 50 F' 80 F 110 F 140 F 157.1 F 0.543 0.660 0.791' 0.979 1.09 L34 1.58 1.88 2.13' 2.36 2.60 2.87 3.39 4.32 5.32 6.25 0.573 0.690 0.829 1.02 1.15 1.40 ' 1.67 1.99 2.24 2.50 2.75 3.02 3.56 4.55 5.61 . 6.62 ' 0.605 0.729 0.878 1.087 1.220 1.491 1.778 2.100 2.380 2.650 2.920 3.200, 3.775 5.050 5.925 6.995 0.638 0.762 0.920 1.15 L29 1.58 : 1.87 2.22 2.51 2.78 3.08 3.38 4.01 5.14 6.34 7.46 0.656 0.781 0.953 1.184 1.335 1.637: 1.937 2.301 2.585 2.873 3.170 3.493 4.115 5.270 6.551 7;670 Steam 297.7 F (50 Lb) 337.9 F (100 Lb) 227.7 F 267.9 F. 0.742 0.886 1.084 1.345 1.520 1.866 2.215 2.641 2.972 3.312 3.655 4.030 4.755 6.120 7.592 ,8.900 0.796 0.955 " 1.166 1.450 1.640 2.015 2.388 2.853 3.215 31582 3.956 4.368 5.153 6.635 81245 ' 9.670 Table 2. Heat Losses frosI Horizontal Bare Copper Pipes Expressed in Btu per'linear foot per degree Fahrenheit difference in temperature between the pipe at S10 F and surrounding stiU air at 70 F Nominal Pipe Rites (Inches) Vi % i m m 2 Outside Diameter (Inches) 0.625 0.875 1.125 1.375 1.625 2.125 Temperature Dippehsncx 140 F 0.405 0.478 0.550 0.623 0.695 0.841 Nominal Pipe Size (Inches) VA 3 3A 4 5 6 Outbids Diameter (Inches) 2.625 3.125 3.625 4.125 5.125 6.125 Temperature Difference 140jF 0.986 1.131 1.276 1.422 1.713 2.004 Table 3. Radiating Surface per Linear Foot of Pipe Nominal Pipe Size . (Inches) A H l m ia 8urpach Area (Sq Ft) 0.22 0.275 0.344 0.435 0.498 ' Nominal ! Pipe Size (Inches) . ' -2 2A 3 3A 4 Surface | Area U (Sq Ft) . | 0.622 0.753 0.917 1 1.047~ 1.178 Nominal Pipe Size (Inches) 5 6 8 10 12 Surface Area (Sq Ft) 1.456 1.734 2.257 . 2.817 3.338