Document rB9jxGv2qM6qRw19zX3ww6raq

American Society of Heating and Ventilating Engineers Guide, 1932 based on the conductivities in Table 4 and were computed from data given in Chapter 22 of The Guide, 1931, in the following manner: Example 1. Determine the coefficient of transmission (U) in Btu per hour per square foot of pipe surface through a 1-in. thickness of magnesia insulation on a 4-in. pipe. The temperature of the pipe is 210 F and the surrounding air temperature is 70 F. Table 3. Areas of Flanged Fittings, Square Feet Nominal. Pipe Size (Inches) i IX iH 2 2X 3 3X 4; 4H5 6 8 9 12 : Flanged Coupling 90 Deg. Ell Long Radius Ell 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 2141 3.00 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 1.481 1.925 1.943 2.53 0.727 1.174 1.332 1.337 1.874 1.815 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 4.44 8.71 11.44 10.57 13.17 13.18 17.23 16.78 22.10 6.71 13.08 17.73 16.35 18.76 19:67 26.65 24.87 34.11 a Including areas or accompanying, flanges bolted to the fitting. Table 4. Conductivities (k) of Various Types of Insulating Materials for Medium and High Temperature Pipes3 Mean Temperatube 85 per 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) Rock Wool Type........ ,............................... High Temperature Type.___.................... (Diatomaceous Earth and Asbestos) Brown Asbestos Type............................ (Felted Fibre) 100 F 0.425 0.530 200 F 300 F 400 F 0.465 0.505 0.550 0.650 0.770' 0.890 500 F 0.590 0.480 0.555 0:630 0.705 0:360 0.415 0.470 0.525 0.585 0.545 0.605 0.665 0.725 0.785 0.350 0.410 0.470 0.530 0.590 0.515 0.545 0.575 0.605 0.635 0.600 0.640 0.675 0.715 0.750 R. H. Heilman. Mechanical Engineering. Vol. 46 (1924). p. 593. Solution. The heat loss coefficient for a 1-in. thickness of pipe insulation for a tem perature difference of 140 deg (from Fig. 5, Chapter 22, The Guide, 1931) is 0.367 Btu per hour per square foot per degree Fahrenheit difference in temperature. The factor for magnesia covering at a temperature difference of 140 deg is 1.214 (by interpolation from Table 7,;Chapter 22, The Guide, 1931). The coefficient of transmission is therefore 0.367 x' 1.214 or 0.446. (See Table 5). 192 Chapter.12--Pipe Insulation -vA Table 5. Coefficients of Transmission (V) for Pipes Insulated with 85 Per Cent Magnesia Type Insulation . These coefficients are expressed in Btu per hour per square foot of pipe surface per degree Fahrenheit difference in temperature between pipe and surrounding still air at 70 F Thicznbss op . Insulation (Inches) 1, IX 2: Nominal Pipe Size (Inches) X. % i : IX IX 2 ' 2X :3 3X 4 : AX 5 :6 :8 9 12 . ; 120 F t 50 F 0.744 0.672 0.613 0.562 0.53Z 0.500 0.475 0.455 0.441 0.429 0.420 0.411 0.402: 0.387 0.380 0.369 Hot Water 150 F 180 F 210 F 227.2 F (5 Lb) Temperature Difference 80T iiof . 140 F 157.2 F 0.754 0.681: 0.621 0.570 0.539 0.506 0.481: 0.461 0.447 0.435 0.425, 0.416 0.408 0.392 0.385` 0.374 0.764 0.689 ,,0.629 0.577 0.546 0,512 .0.487 .0.467 0.452 0.441 0.431 ' 0.422 . 0.413 0,397 0.390 0,378 0.774 0.697 0.637 0.585 0.553 0.519 0.493 0.474 0.458 0.446 0.437 0.427 0.419 0.403 0.395 0.383 0.779 0.701 0.641 0.589 0.557 0.523 01-497 0.477 0.462 0.449 0.440 0.430 0.422 0.405 0.398 0.386 Steam 298.7 F (10 Lb) 337.9 F (100 Lb) 228.7 F 0.802 0.721 0.659 0.606 0.573 0.538 0.512 0.492 0.475 0.463 0.453 0:443 0i435 0:418 0.410 0:398 267.9 F 0.814 0.731 0.670 0.617 0.582 0.547 0.520 0.500 0.483 0.471 0.460 0.450: 0.442 0.425 0.417 0.405 X 1 1 IX IX 2 2X 3 3X 4 4X 5 6 8 9 12 0.617 0.550 0.496 0.453 0.424 0.394 0.371 0.352 0.339 0.328 0.320 0.312 0.303 0.287 0.280 0.272 0.625 0.558 0.503 0.459 0.430 0.400 0.376 0.357 0.343 0.333 0,324 0.316 0.307 0.291 0.284 0.275 0.633 0.566 0:511 0.465 0.436 0.405 0.382 0.362 0.347 0.337 0.328 0.320 .0.311 0.295 0.288 0.279. 0.642 0.573 0.518 0.472 0.442 0.410 0.386 0.367 0.351 0.341 0.332 0.324 0.315 0.299 0.292 0.283 01646 0.577 0.522 0.475 0.445 0.413 0.389 0.370 0.354 0.343 0.334 0.326 0.318 0.301 0.294 0.285 0:665 0.596 01540' 0.490 0.459 01427 0.401 0.380 0.364 0,353 0.343 0.336 0.328 0.311 0.303 0.294 0.676 0.606 0.549 0.498 0.467 0.434 0.408 0.387 0.370 0.359 0.350 0.342 0.333 0.316 0.308 0.299 X X 1 : IX IX 2 : 2X 3 . 3X 4 iX 5 6 '8 ;9 0.543 0.484 0.433 0.393; 0.365 0.338: 0.316: 0.297 0.284: 0.275: 0.266 0.258 0.250 0.236 0.228 0.219 0.551 0.490 0.439 0.398 0.370 0.343 0.320 0.301 0.288 0.278 0.270 0.262 0.254 0.239 0.231 0.222 0.558 0.497 .0:445; 0.403: 0.376 0.347 0.324 0.305 0.292 0.282 0.273 0.265 0.257 0.242 0.234 0.225: 0.565 0.503 0.451 0.409 0.381 0.351 0.328 0.309: 0.295: 0.285; 0.276 0.268 0.260 0.245 0.237 0.228 0.569 0.507 0.454 0.412 0.384. 0.354 0.331 0.312 0.297 0.287 0.278 0.270 0.262 0.247 0.239 0.230 0.587 0.523 0.467 0.424 0.397 0.364 0.341 0.321 0.306 0.;296 0.286-1 0.278 0.270 0.255 0.246 0.237 0.597 0.532 0.476 0.432 0.402 0.370 0.347 0.326 0.311 0.301 0.290 0.283 0.274 0.258 0.250 0.240