Basic Documentation
Table Of Contents
- About this Application Guide
- Chapter 1–Introduction
- Chapter 2–Physics of Sound
- Chapter 3–HVAC Sound Sources
- Chapter 4–HVAC Sound Attenuation
- Introduction to HVAC Sound Attenuation
- Plenums
- Duct Attenuation
- Duct Takeoffs and Divisions
- Duct Silencers
- End Reflection
- Environment Adjustment Factor
- Space Effect
- Radiated Sound Attenuation
- Chapter 5–HVAC System Sound Analysis
- Chapter 6–Minimizing HVAC Sound
- Appendix
- Glossary
- Index
Purpose of this Guide
Blade Frequency Increment 24
Fan Efficiency 25
Fan Sound Power Level Data 25
Fan Sound Power Level Calculation 26
Step 1. Actual Operating Conditions Increase 26
Step 2. Blade Frequency Increment (BFI) 26
Step 3. Efficiency Correction 27
Example Fan Sound Power Level Calculation 28
Step 1. Actual Operating Conditions Increase 28
Step 2. Blade Frequency Increment (BFI) 29
Step 3. Efficiency Correction 29
Damper Airflow Noise 30
U (Velocity Factor) 30
Calculate Pressure Loss Coefficient C 30
Calculate Damper Blockage Factor BF 31
Calculate the Velocity Factor U 31
K Factor 32
Example Damper Sound Power Level Calculation 33
Elbow Airflow Noise 34
K Factor 35
Example Elbow Sound Power Level Calculation 36
Junction and Takeoff Airflow Noise 38
K Factor 38
JC Factor 39
Example Duct Takeoff Sound Power Level Calculation 40
Air Delivery Device Sound 43
Flexible Duct Connection to Diffusers 44
Discharge Sound and Radiated Sound 44
Sound Breakout and Break-in 45
Laboratory Elements 45
Chapter 4–HVAC Sound Attenuation 47
Introduction to HVAC Sound Attenuation 47
Plenums 48
Example Plenum Attenuation Calculation 49
Duct Attenuation 51
Rectangular Unlined Sheet Metal Ducts 51
Example Rectangular Duct Attenuation Calculation 51
Rectangular Unlined, Externally Insulated, Sheet Metal Ducts 53
Rectangular Acoustically Lined Sheet Metal Ducts 54
Round Unlined Sheet Metal Ducts 57
ii Siemens Building Technologies, Inc.