TABLE OF CONTENTS Introduction. In addition to fulfilling air conditioning requirements, an air handling system must meet acceptable noise and vibration criteria. The purpose of the following section is to provide design engineers of air handling systems with guidelines for selecting the proper criteria for building spaces, and methods for specifying design requirements on system. Common sources of vibrations in buildings are fans, blowers, water chillers, water pumps, and air compressors. Methods for specifying and reducing noise and vibration levels for ducted systems will be given.
Ducted systems treated in this chapter are used to transmit air from a fan or blower to the necessary locations. Air transmission may be for central station air conditioning, industrial ventilating systems, or industrial applications such as process cooling and furnace air supply, among others. Although the fan or blower is usually considered the major source of noise in such systems, the flow of air through duct elements like elbows, turning vanes, and flow control valves can also produce vibration and, therefore, sound.
The design engineer should be aware of noise and vibration principles, since these have become a major concern in the acceptability of air handling systems. While it is not economical to over design a system for noise or vibration control, disastrous results can occur if potential problem areas are not considered in the design stage. Optimal design avoids overdesign but allows for a system that meets accepted criteria for the use of building space.
Definitions and Terminology.
