Document zoVm04q6NmrM9dM0wKv1j9L4n

American Society of Heating and Ventilating Engineers Guide, 1929 Table 2. Radiating Surface per Linear Foot of Pipe Pips Sizb In. Surface Sq. Ft. Pipe Size In. Surface Sq. Ft. Pipe Size In. Surface Sq. Ft. K 0.22 K 0.275 1 0.344 IH 0.435 ik 0.498 2 0.622 2K 0.753 3 0.917 3K 1.047 4 1.178 5 1.456 6 1.734 8 2.257 10 2.817 12 3.338 INSULATION OF HOT WATER, LOW AND HIGH PRESSURE STEAM LINES The conductivities, in B.t.u. per square foot per hour per inch thick per degree Fahrenheit temperature difference between inner and outer surfaces of the insulation are given in Fig. 4 for various insulations./ In this figure the conductivities are plotted as functions of the mean tem- peratures or the mean of the inner and outer surface temperatures of the insulations. ! This method of plotting conductivities, enables one to readily calculate the heat loss through single or compound sections. It should be empha sized that in this figure, the conductivities given for the various insula tions are the average values from a number of tests on each type of material, also that all variables due to differences in.thickness, different pipe sizes, and different air conditions are eliminated. The heat losses through any of the insulations shown in Fig. 4 for various thicknesses of covering and for any temperatures generally used Table 3. Areas of Flanged Fittings, Square Feet Nominal Pipe Size LD. i" IlKw' 2". 2K" . 3' 3K' 4' 4K' 5" 6* 7" . 8' 9" 10' 12' 14" O. D. 15' O. D. 16" O. D. Flanged Coupling 90 Deg. Ell Lonq Radius Ell Tee Cross Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy 0.320 0.438 0.795 1.015 0.892 1.083 1.235 1.575 1.622 2.07 0.383 0.510 0.957 1.098 1.084 1.340 1.481 1.925 1.943 2.53 0.477 0.727 1.174 1.332 1.337 1.874 1.815 2;68 2.38 3.54 0.672 0.848 1.65 2.01 1.84 2.16 2.54 3.09 3.32 4.06 0.841 1.107 2.09 2.57 - 2.32 2.76 3.21 4.05 4.19 5.17 0.945 1.484 2.38 3.49 2.68 3.74 3.66 5.33 4.77 6.95 1.122 1.644 2.98 3.96 3.28 4.28 4.48 6.04 5.83 7.89 1.344 1.914 3.53 4.64 3.96 4.99 5.41 7.07 7.03 9.24 1.474 2.04 3.95 5.02 4.43 5.46 6.07 7.72 7.87 10.07 1.622 2.18 4.44 5.47 5.00 6.02 6.81 8.52 8.82 10.97 1.82 2.78 5.13 6.99 5.99 7.76 7.84 10.64 10.08 13.75 2.17 3.46 6.17 8.62 7.38 9.73 9.37 12.33 12.00 16.83 2.41 3.77 6.98 9.76 8.56 11.09 10.55 14.74 13.44 18.97 3.00 4.44 8.71 11.44 10.57 13.17 13.18 17.23 16.78 22.10 3.43 5.20 10.18 13.58 12.35 15.60 15.41 20.41 19.58 26.26 4.41 6.71 13.08 17.73 16.35 18.76 19.67 26.65 24.87 34.11 5.39 8.30 16.38 22.31 20.17 25.70 24.81 33.63 31.48 43.15 6.18 9.52 18.50 25.28 22.92 29.34 27.91 38.04 35.48 48.79 6.69 10.05 20.17 27.18 25.41 31.73 30.32 40.94 38.34 52.35 252 Chapter XV--Heat Insulation for Pipes and Surfaces in engineering practice can be obtained from Table 5 and Figs. 5 to 7 inclusive. In these curves the unit loss through 1, 13^ and 2-in. thick covering is given for temperature differences up to 700 deg. fahr. The loss through other thicknesses of covering can be obtained from the curves by inter polation. Table 5 gives the factor by which the loss from the curves shown in Figs. 5 to 7 must be multiplied to give the loss through any of the coverings whose conductivity values are given in Fig. 4. Table 4. Values of k Corresponding to Commonly Used Coverings Hair Felt........................ Keystone Hair.............. Wood Felt...................... Cork, 6.9 lb. per cu. ft. Cork, 9.7 lb. per cu. ft. Cork, 16 lb. per cu. ft. Per Cent Variation k from k = 0.3 0.246 0.27 0.36 0.27 0.30 0.35 -18% -10% +20% -10% 0% +17% Table 5. Pipe-Covering Factors Ttpe or Covering Temperature Difference. Pipe to Air, Deg. Fahr. 100 200 300 400 500 000 . 700 85% Magnesia................... .......... :........... 1.234 Laminated Asbestos Type. Approx. 20 laminations per inch. _ ................ 1.515 Laminated Asbestos Type. Approx. 30 to 40 laminations per inch............ 1.022 High Temperature........................ ........... 1.438 Felted Brown Asbestos Fibre. -......... 1.665 Rock Wool................. ....... ........................ 1.058 Corrugated Asbestos, 8 plies per inch 1.349 Corrugated Asbestos, 4 plies per inch 1.520 1.184 1.474 1.019 1.358 1.577 1.045 1.340 1.550 1.148 1.441 1.016 1.292 1.505 1.035 1.333 1.580 l.iii 1.409 1.013 1.233 1.436 1.022 1.323 1.605 1.082 1.383 1.010 1.190 1.387 1_.0_2_0 1.051 1.360 1.007 1.147 1.340 1_.0_1_4 1.025 1.345 1.005 1.109 1.300 1_.0_1_0 Table 6. Thicknesses of Insulation Ordinarily Used Steam Pressures (Lb. Gage) Steam Temperatures (Deg. Fahr.) Thickness of Insulation Pipe larger Pipes Pipes than 4. in. 2 in. to 4 in. Hin tolMin. 0 to 25 25 to 100 100 to 200 Higher Pressure or Superheat Higher Pressure or Superheat 212 to 267 267 to 338 338 to 388 388 to 500 500 to 600 1 in. IK in. 2 in. 2K in. 3 in. 1 in. 1 in. . IK in. 2 in. 2^ in. 1 in. 1 in. 1 in. IK in. 2 in. Example.--Determine the heat flow in B.t.u per hour per square foot of pipe surface through a magnesia covering 1 in. thick on a 4-in. pipe. Solution.--The temperature of the pipe is 270 deg. fahr. and the room temperature, 70 deg. fahr. The loss through a covering 1 in. thick on a 4-in. pipe at 200 deg.- tem perature difference from Fig. 5 = 0.395; the factor for magnesia at 200 deg. temperature difference from Table 5 = 1.184;. then the heat loss through the magnesia covering = 0.395 X 1.184 X 200 = 93.5 B.t.u. per square foot of pipe surface per hour. 253 X'