Chapter hvac engineering Fundamentals: Part 1 Introduction

Design Procedures: Part 3
113
TABLE
5.1 Duct Material Roughness Factors
SOURCE
: Copyright 2001, American Society of Heating, Refrigerating and Air Con-
ditioning Engineers, Inc., www.ashrae.org. Reprinted by permission from ASHRAE
Handbook,
2001 Fundamentals,
Chap. 34, Table 1.
nificant differences in elevation or temperature. Table 5.1 provides
information on roughness factors for several common duct materials.
Figure 5.21 provides
K
m
factors for four degrees of roughness. The
pressure loss from the friction chart is multiplied by the
K
m
to get the
friction loss at a different roughness. Roughness correction is essential
to correct design.
Friction loss corrections for the density, viscosity, and humidity of
nonstandard air are quite complex and are usually neglected, al-
though this is technically incorrect.
Design Procedures: Part 3
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