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Good Practices on Ventilation System Noise Control

The inclusion of any information of any company or product or reference to brand names of any particular product in this booklet does not in any way imply recommendation or endorsement by the Government of the Hong Kong Special Administrative Region (the Government). The inclusion or reference is for demonstration purpose only and the non-inclusion of any product or company herein shall not be construed as disapproval of the product or company by the Government. The data regarding any product herein have been certified to be accurate by relevant manufacturers or their authorized agents or representatives. However, no warranty or guarantee whatsoever is or shall be construed as being given by the Government in respect of any product referred to herein. Readers are advised to seek independent experts or technical advice regarding the operation, use, installation, maintenance or otherwise of any product referred to herein.

CONTENTS

1. INTRODUCTION
2. QUICK REFERENCE GUIDE
3. PLANNING AGAINST NOISE PROBLEMS
3.1 Positioning of Equipment
3.2 Selection of Quiet Equipmen
3.3

Scheduled Maintenance
4. PROBLEMS AND PRACTICAL REMEDIES ON VENTILATION SYSTEM NOISE
4.1 Air-borne Noise from Air-cooled Chillers
4.2 Structure-borne Noise from Air-cooled Chillers
4.3 Air-borne Noise from Water Cooling Towers
4.4

Structure-borne Noise from Water Cooling Towers
4.5 Air-borne Noise from Fans
4.6 Structure-borne Noise from Fans
4.7 Air-borne Noise from Ducts
4.8 Important Note
5. RECOMMENDED PRACTICAL REMEDIES FOR DIFFERENT EXCEEDANCE LEVELS
6. GLOSSARY OF ACOUSTIC TERMINOLOGY

APPENDICES

I. STATUTORY CONTROL OVER NOISE
II. NOISE PREDICTION
III. TYPICAL SOUND POWER LEVELS OF VENTILATION EQUIPMENT
IV. COMPLETE ENCLOSURES
V. PARTIAL ENCLOSURES
VI. BARRIERS
VII. INERTIA BLOCKS
VIII. VIBRATION ISOLATORS
IX. SILENCERS
X. FLOATING FLOORS
XI. VIBRATION IDENTIFICATION GUIDE
XII. GUIDELINES FOR CENTRIFUGAL AND AXIAL FAN INSTALLATIONS
XIII. EXAMPLES OF PRACTICAL NOISE CONTROL MEASURES
XIV. REFERENCE
XV. OTHER RELEVANT NOISE CONTROL MATERIALS
XVI. ADDRESSES AND TELEPHONE NUMBERS OF ENVIRONMENTAL PROTECTION DEPARTMENT'S OFFICES

LIST OF FIGURES

Figure 1 Complete Enclosure and Silencers
Figure 2 Air-borne Noise from Air-cooled Chillers
Figure 3 Barrier for Air-cooled Chillers
Figure 4 Floating Floor and Complete Enclosure for Air-cooled Chillers
Figure 5 Structure-borne Noise from Air-cooled Chillers
Figure 6 Vibration Isolation of Air-cooled Chillers
Figure 7 Air-borne Noise from Water Cooling Towers
Figure 8 Barrier and Vent Cowl for Water Cooling Towers
Figure 9 Complete Enclosure for Water Cooling Towers
Figure 10 Structure-borne Noise from Water Cooling Towers
Figure 11 Vibration Isolation of Water Cooling Towers
Figure 12 Air-borne Noise from Axial and Centrifugal Fans
Figure 13 Duct Diversion
Figure 14 Complete Enclosure and Silencers for Axial and Centrifugal Fans
Figure 15 Structure-borne Noise from Axial and Centrifugal Fans
Figure 16 Vibration Isolation of Axial and Centrifugal Fans
Figure 17 Duct Noise
Figure 18 Use of Damping Compound and Composite Lagging
Figure 19 Partial Enclosures
Figure 20 Barriers
Figure 21 Metal Springs
Figure 22 Isolation Pads
Figure 23 Silencers
Figure 24 Floating Floors
Figure 25 Guidelines for Centrifugal Fan Installations
Figure 26 Guidelines for Axial Fan Installations
Figure 27 Examples of Noise Control Measures

LIST OF TABLES

Table 1 Quick Reference Guide
Table 2 Recommended Practical Remedies
Table 3 Acceptable Noise Level (dB(A)), at 1m Facade
Table 4 Acceptable Noise Level (dB(A)), at an Internal Location
Table 5 Distance Attenuation at Given Distances
Table 6 Summation of Noise Levels
Table 7a Typical Sound Power Levels of Air-cooled Chillers
Table 7b Typical Sound Power Levels of Water Cooling Towers
Table 7c Typical Sound Power Levels of Fans
Table 8 Sound Insulation Materials for Enclosures
Table 9 Guide for Inertia Block Selection
Table 10 Minimum Static Deflection for Various Speeds of Machines
Table 11 Vibration Identification Guide

 
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Last Revision Date : 06 May 2008