Document NEJLzKMvZxVKBzgZ0ok00OyJw

HEATING VENTILATING AIR CONDITIONING GUIDE 1944 CHAPTER 18. PIPE INSULATION The heat losses through 1, 1J4, and 2-in., thick 85 per cent Magnesia type of insulation for temperature differences between the pipe and the surrounding atmosphere up to 280 F are shown in Figs. 1, 2, and 3. Standard thicknesses of 85 per cent Magnesia pipe covering are not exactly 1 in. However, the loss through any given thickness of insulation can be obtained by interpolation. Also, the losses through any of the Fig. 2. Heat Loss Through 1J4 In. Thick 85 per cent Magnesia Type Covering . insulations given in Table 8 can be obtained by multiplying the losses obtained from Figs. 1, 2, or 3 by the factors given in Table 9. The rate of heat loss from a surface maintained at constant temperature is greatly increased by air circulation over the surface. In the case of well-insulated surfaces, the increases in losses due to air velocity are very small as compared with increases from bare surfaces, because of the fact that air flowing over the surface of the insulation can increase only the rate of heat transfer from surface to air, and cannot change the internal 349