Document 2jmZkYMexXXgJ78yqO42Q92L5

B.T.U. PER LINEAR FOOT PER HOUR PER DEG FAHR TEMPERATURE DIFFERENCE HEATING VENTILATINC AIR CONDITIONING CUIDE 1940 Fig. 2. Heat Loss Through 1 In. Thick 85 per cent Magnesia Type Covering 690 CHAPTER 40. PIPE AND DUCT INSULATION Table 12. Areas of Flanged Fittings, Square Feet* Nouiual Pipe Sue (Inches) i IX IX 2 3 3% 4 4H 5 6 8 10 (2 Flanged Coupling 90 Deo Ell Long Radius Rt.i. Tee Cboss Standart Extra Heavy Stand&rc Extra Heavy Standard Extra Heavy Standard Extra Heavy Standarc Extra Heavy 0.320 0.383 0.477 0.672 0.841 0.438 0.510 0.727 0.848 1.107 0.795 0.957 1.174 1.65 2.09 1.015 1.098 1.332 2.01 2.57 0.892 1.084 1.337 1.84 2.32 1.083 1.340 1.874 2.16 2.76 1.235 1.481 1.815 2.54 3.21 1.575 1.925 2.68 3.09 4.05 1.622 1.943 2.38 3.32 4.19 2 07 2.53 3.54 4.06 .5 17 0.945 1.484 2.38 1.122 1.644 2.98 3.49 3.96 2.68 3.28 3.74 4.28 3.66 4.48 5.33 6.04 4.77 5.83 6.0.5 7 80 1.344 1.914 3.53 1.474 2.04 3.95 4.64 5.02 3.96 4.43 4.99 5.46 5.41 6.07 7.07 7.72 7.03 0 24 7.87 1007 1.622 1.82 2.41 3.43 4.41 2.18 2.78 3.77 5.20 6.71 4.44 5.13 6.98 10.18 13.08 5.47 6.99 9.76 13.58 17.73 5.00 5.99 8.56 12.35 16.35 6.02 7.76 11.09 15.60 18.76 6.81 7.84 10.55 15.41 19.67 8.52 10.64 14.74 20.41 26.65 8.82 10.08 13.44 19.58 24.87 10 97 13.75 18.97 26.26 34.11 Including areas of accompanying flanges bolted to the fitting. ,____ a,..w amiuai neat luss irom xoo it oi z in. bare pipe in service 4000 hr per year. The pipe is carrying steam at 10 lb pressure and is exposed to an average air temperature of 70 F. Solution. The pipe temperature is taken as the steam temperature, which is 239.4 F, obtained by interpolation from Table 8 Chapter 1. The temperature difference between the pipe and air = 239.4 -- 70 169.4 F. By interpolation of Table 6 between tem perature differences of 157.1 and 227.7 F, the heat loss from a 2 in. pipe at a temperature difference of 169.4 F is found to be 1.624 Btu per hour per linear foot per degree tem perature difference. The total annual heat loss from the entire line = 1.624 X 169.4 X 165 (linear feet) X 4000 (hr) = 181,600 Mb. Example 2. Coal costing $11.50 per ton and having a calorific value of 13,000 Btu per pound is being burned in the furnace supplying steam to the pipe line given in the previous example. If the system is operating at an overall efficiency of 55 per.cent, determine the monetary value of the annual heat loss from the line. Solution. The cost of heat per 1000 Mb supplied to the system = 1,000,000 X 11.5 Table 13. Conductivity (k) of Various Types of Insulating Materials for Medium and High Temperature Pipes* Types of Insulating Materials 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. Laminated Asbestos Type (14-20 Laminations per 1 in. Mineral Wool TvDe. High Temperature TvDe. (Diatomaceous Earth and Asbestos! Brown Asbestos Tvne (Felted Fiber) Mean Temperature. Deg F- 100 0.359 0.495 0.505 0.326 0.374 0.350 0.576 0.338 200 0.403 0.618 0.598 0.380 0.445 0.410 0.614 0.396 300 0.448 0.741 0.692 0.434 0.518 0.470 0.652 0.453 400 0.493 0.864 0.786 0.488 0.589 0.530 0.689 0.510 500 0.539 -- 0.543 0.662 0.590 0.726 0.568 From tests conducted at Mellon Institute. 691