Document gajyBEYMXpYZwaw4rDR5d2Jb9

American Society of Heating and Ventilating Engineers Guide, 1930 the curves by the percentages indicated in the last column of Table 4. These percentages will give values approximately correct. In Fie 7- /* = temperature of air on warm side of insulation. \tul = temperature,of the medium on cold side of insulation. Chapter 24--Insulation for Pipes and Surfaces Fig. 6. Temperature Difference between Air and Dew Points at Different Relative Humidities Thickness, Inches Fig. 5. Heat Loss through 2 in. thick Covering EFFECT OF AIR VELOCITY ON SURFACE LOSSES The rate of heat loss from a surface maintained at constant temperature is greatly increased by air circulation over the surface. Fig. 8 is based on Langmuir's equations {Trans. Am. Electro-Chem. Soc., Vol. 23). Other investigators have shown even greater increases in rates of heat loss from bare surfaces due to air velocity. In the case of well-insulated surfaces the increases in losses due to air velocity are very small as compared with increases shown above for 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, 412 Thickness, Inches Temperature Difference (t-tm), Deg. Fahr. 1-in Pipe 3-iri. Pipe - .Temperature Difference 10-in. Pipe Deg. Fahr. Flat Surface Fig. 7. Thickness of Insulation to Prevent Sweating 413