Chapter hvac engineering Fundamentals: Part 1 Introduction

Engineering Fundamentals: Part 5
493
Figure 20.5
RC curve. (
SOURCE
: Copyright 1997, American Society of Heating, Refrig-
erating and Air Conditioning Engineers, Inc., www.ashrae.org. Reprinted by permission
from ASHRAE Handbook,
1997 HVAC Fundamentals,
Chap. 7, Fig. 5.)
no hisses or rumbles, is usually unobtrusive and acceptable, even
when at a fairly high level, as long as it is essentially constant.
20.5.3
Design goals
Design goals for background noise levels for various environments are
given in Table 20.3. These are stated in terms of NC curves. The table
omits criteria for concert halls, theaters, and recording studios; these
are generally 25 NC or less. Industrial environments are not listed
but tend to be higher, due to industrial processes. Government agen-
cies, such as the Occupational Safety and Health Administration
(OSHA), specify maximum noise levels and duration of exposure for
industrial environments. Because most of these exceed the sound level
Engineering Fundamentals: Part 5
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