Document 91y6axd0QDxK8nOVq0K6NNyr3

American Society of Heating and Ventilating Engineers Guide and proceed to the right to a point representing the given numk-i hours of. operation per year; then proceed vertically to the line ^ senting the given value of heat; thence horizontally, to the right line representing the given temperature difference; thence vertical? the line representing the conductivity of the given material; thence w zontally, to the left, to the line representing the given discount on ' (L. B. McMillan, Iron and Steel Engineer, July 1925.) Fig. 9. Heat Losses, from Surfaces Exposed to Various Air Velocities material; thence vertically to the curve representing the required per cent return on the investment; thence horizontally, to the left, to the curve representing the given pipe size; thence vertically to the scale at the top; of the sheet where the economical thickness may be read off directly. The dotted line,on the chart illustrates its use in solving a typical example., It is impossible to determine accurately the economic thickness of 340 MOORS OPERATION PER YEAR NO (L. B. McMillan, Proc. National Dist, Healing Ass'n., Vol. 18, p. 131.) '`r^!'3> /. Fig. 10. Chart for Determining EconoJ mical Thickness of Insulation