Document 15mqwb4pV1ndMDxLdkR128o9K

Heating Ventilating Air Conditioning Guide 1938 Table 4. Heat Loss from Horizontal Tarnished Copper Pipe Expressed in Btu per linear foot per degree Fahrenheit between the pipe and surrounding still air at 70 F Nominal Peps Size (Inches) x M i iK \X 2 2X. 3 IX 4 4H 5 6 8 Hot Water (Type K Copper Tube) Steam (Standard Pipe Sue Pipe) 120 F 150 F 180 F 210 F 1 227.1 F (5 Lb) 297.7 F (50 Lb) 337.9 F (100 Lb) Temperature Difference 50 F' 0.250 0.340 0.440 0.500 ' 0.580 0.730 0.880 1.040 1.180 1.460 80F 0.287 0.381 0.475 0.559 0.656 0.825 1.000 1.175 1.350 1.500 1.600 1.840 2.400 1.812 2.125 2.685 110 F 0.300 0.409 0.S09 0.618 0.710 0.890 1.091 1.272 1.454 1.635 1.980 2.270 2.910 140 F 1 0.321 0.429 0.536 0.622 0.750 0.957 1.143 1.343 1.535 1.715 2.071 2.430 3.110 157.1 F 0.433 0.533 0.636 0.764 0.904 1.101 1.305 1.560 1.750 1.941 2.131 2.387 2.740 3.310 227.7 F 0.500 0.543 0.746 0.878 1.053 1.273 1.490 1.800 2.020 2.240 2.465 2.770 3.210 4.050 267.9 F 0.530 0.654 0.803 0.934 1.120 1.364 1.605 1.940 2.170 2.430 2.650 2.990 3.440 4.370 linear foot of pipe. Table 5 gives these areas for various standard pipe sizes, and Table 6 for copper tubing, while Table 7 gives the area in square feet for flanges and fittings for various standard pipe sizes. Very often, when pipes are insulated, flanges and fittings are left bare due to the belief that the losses from these parts are not large. However, the fact that a pair of 8 in, standard flanges having an area of 2.41 sq ft Table 5. Radiating. Surface per Linear Foot of Pipe Nominal , Pipe Sue (Inches) "X Vt, l W \x Surface ` Area (Sq Ft) 0.22 0.275 0.344' 0.435. 0.498 Y Nominal Pipe Size (Inches) 2 2X 3 3^ 4 . Surface Area (Sq Ft) 0.622 0\753 0.917 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 Table 6: Radiating Surface per Linear Foot of Copper Tubing (Inches) ' w Vi. 1 . mix (Sq Ft) 0.164 0.229 0.295 .. .0.360. 0.426 Tube Size (Inches) 2 2X 3 3X 4 Surface Area (Sq Ft) 0.556 0.687 0.818 0.949 1.080 ' Tube Size (Inches) 5 6. 8 Surface Area (Sq Ft) 1.342 .. 1.604 2.128 722 Chapter 39. Piping and Duct Insulation Table 7. Areas of Flanged Fittings, Square Feet3 Nominal Pipe Size (Inches) i imx 2 2X 3 m 4 iX 5 6. 8` 10 . 12 Flanged Coupling 90 Deg Ell Long Radiub Rij, Tee Cross Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy Standard Extra Heavy 0.320 0.383 0.477 0.672 0.841 0.945 1.122 1.344 1.474 1.622 1.82 2.41 3.43 4.41 0.438 0.795 1.015 0.892 1.083 1.235 1.575 1.622 2.07 0.510 0.957 1.098 1.084 1.340 lt.481 1.925 1.943 2.53 0.727 1.174 1.332 1.337 1.874 11.815 2.68 2.38 3.54 0.848 1.65 2.01 1.84 2.16 2.54 3.09 3.32 4.06 1.107 2.09 2.57 2.32 2.76 3.21 4.05 4.19 5.17 1.484 2.38 3.49 2.68 3.74 3.66 5.33 4.77 6.95 1.644 2.98 3.96 3.28, 4.28 4.48 6.04 5.83 7.89 1.914 3.53 4.64 3.96 4.99 5.41 7.07 7.03 9.24 2.04 3.95 5.02 4.43 5.46 6.07 7.72 7.87 10.07 2.18 4.44 5.47 5.00 6.02 6.81 8.52 8.82 10.97 2.78 5.13 6.99 5.99 7.76 ' 7.84 10.64 10.08 13.75 3.77 6.98 9.76 8.56 11.09 10.55 14.74 13.44 18.97 5.20 10.18 13.58 12.35 15.60 15.41 20.41 19.58 26.26 6.71 13.08 17.73 16.35 18.76 19.67 26.65 24.87 34.11 ^Including areas of accompanying flanges bolted to the fitting. would lose, at 100 lb steam pressure, an amount of heat equivalent to more than a ton of coal per year shows the necessity for insulating such surfaces. HEAT LOSSES FROM INSULATED PIPES The conductivities of various materials used for insulating steam and hot water pipes are given in Table 8. In this table the conductivities are given as functions of the mean temperatures'or the mean of the inner and outer surface temperatures of the insulations. This method of stating conductivities makes it possible to readily calculate the heat loss through single or compound sections. It should be emphasized that the conduc tivities given in Table 8 for the various insulations are the average of kTable 8. Conductivities ( ) of Various Types of Insulating Materials for Medium and. High Temperature Pipes3 Ttprs of Insulating Material* 85 oer cent Magnesia Type Corrugated Asbestos Type.-............. (4 Plies per 1 in. thick) Corrugated Asbestos Type--............. (8 Plies per 1 in. thick) Laminated Asbestos Type (30-40 Laminations per 1 in. thick) Laminated Asbestos Type (20 Laminations per 1 in. thick) kock Wool IvDe....................... High Temperature Type.......................... (Diatomaceous Earth'and Asbestos) Brown Asbestos Type (Felted Fibre) Mean Temperature 100 F 200 F 0.425 0.465 0.530' 0.650 300 F 0.505 0.770 0.480 0.555 0.630 0.360 0.415 0.470 0.545 0.605 0.665 0.350 0.410 0.470 0.515. 0.545 0.575 0.600 0.640' 0.675 400 F 0.550 0.890 0.705 0.525 0.725 0.530 0.605 0.715 500 F 0.590 0.585 0.785 0.590 0.635 0.750 R. H. Heilman. Mechanical Engineering, VoL 46 (1924), p. 593. 723 ./