Absorptive Silencers s UIVERSAL EERGY EVIROMETAL
The absorptive type silencer is the classic dissipative design that absorbs noise energy by the use of various types of fibrous packing materials. As sound waves pass through the spaces between the tightly packed sound absorbent small diameter fibers, the resulting viscous friction dissipates the sound energy as small amounts of heat. Absorbent silencers are very effective on high frequency noise (00-,000 Hz). At frequencies above and below this range, attenuation is somewhat diminished. Since noise is absorbed by the packing material, absorptive silencers do not rely on internal baffles, tubes, or chambers to achieve noise reduction. As a result absorptive silencers generally utilize a "straight-through" gas flow path that will minimize flow restriction. B&W Universal Absorptive Series of silencers are listed below. General Information s.1 Absorptive Rotary Silencers ositive Blower Silencers U Series remium grade straight-through silencer available in pipe sizes of ½" to ". Attenuation is similar to the SUS Series. U Series Standard grade straight-through silencer available in pipe sizes " to ". For better performance use SUS, SU, or SU series. SU Series remium grade full-flow annular type silencer available in pipe sizes of " to ". SU Series Standard grade annular type silencer with performance one grade below the SUS Series. The SU Series is available in pipe sizes " to ". For enhanced performance, use SU or SUS series. Sizing Information, ressure Drop Data The flow area through the silencer must be sufficient to accommodate the maximum flow without imposing excessive pressure drop. The following instructions enable the selection of the proper silencer size and determination of actual pressure drop. These instructions assume air as the flowing gas. For other gases, density and other corrections may be necessarycontact B&W Universal for assistance. Data required: air flow rate (actual CFM) temperature ( F) pressure (psig) maximum pressure drop (inches of water) 1 Determine maximum velocity..7 T 0 V 0 c.7 V = air or gas velocity, ft/min (see note 1) = maximum pressure drop, inches of water c =silencer pressure drop coefficient (see Table 1) T =air temperature, F (see note ) =operating pressure, psig (If at atmospheric pressure, pressure ratio is unity and may be omitted from equation. If exceeds 1 psig, contact B&W Universal for recommendations.) Determine flow area required. Q A V A = flow area required, ft Q = air flow rate (actual CFM) Actual CFM (Standard CFM) From Table, select size with flow area equal to or greater than that calculated. Determine actual gas velocity in ft/min. A = flow area from Table Determine actual pressure drop. c Q V actual A.7 T 0.7 V actual.7 0 T 0.7 c =silencer pressure drop coefficient (see Table 1) 1 ressure Drop Coefficients Silencer Series U, U SU SU, SU Flow Area Size Diameter Size (in) ³ ₄ 1 1 1 otes Flow Area (ft ) 0.00 0.001 0.00 0.0 0.0 0.0 0.09 0.07 0.07 0. 0.19 0.9 0. 0.79 1.07 1. 1.. ressure Drop Coefficient (C)..7. Diameter Size (in) 0 7 Flow Area (ft )..1.7..9.. 7.1 7.9.7 9.. 11.. 1.9 19... 1. Since "self noise" and aerodynamic noise" increase with velocity, absorbent silencers are usually sized for,000 to,000 ft/min. In no case should the velocity exceed 1,000 ft/min. regardless of pressure drop allowed.. Typical attenuation curves indicate the characteristics of the silencer series and are neither a minimum nor a guarantee for an individual silencer. Individual silencer performance can be affected by sound source characteristics including pure tones, flow velocity, adjacent piping and temperature. 1 7
. Absorptive Rotary ositive Silencers Blower Silencers U Series Straight-Through Attenuation, db Typical Attenuation Curve 1 0 0 00 1K K K K Octave Band Center Frequency, Hz The U Series is a premium grade straightthrough absorptive silencer which provides excellent noise attenuation due to its high length to diameter ratio. It is especially well suited for inlet applications on small rotary positive, centrifugal blowers, or discharge of vacuum pumps. The U Series consists of mild steel construction and enamel paint. 1 7 ote U series standard paint and acoustical packing are suitable for F. Common Applications rotary positive/centrifugal blowers vacuum pump discharge air valves and cylinders small low-pressure vents high frequency noise sources L H D Sizes ½" through 1-1/" are constructed with one-piece tapped heads. The tapped opening is approximately flush with the end of the shell. Sizes ½" through " utilize female T pipe connections. Sizes " and " utilize /10 ASI drilled plate flanges. Absorptive Material Straight-Through Model U- U-³ ₄ U-1 U-1¹ ₄ U-1 U- U- U- U- U- U- art 11-10-AA 11-170-AA 11-1-AA 11-1-AA 11-11-AA 11--AA 11--AA 11--AA 11--AA 11--AA 11--AA D L H Weight ³ ₄ 1 1¹ ₄ 1 ¹ ₄ ¹ ₄ ¹ ₄ ¹ ₄ ¹ ₄ ¹ ₈ ¹ ₈ ⁵ ₈ 11 19³ ₄ ⁷ ₈ 7 ¹ ₈ 11 1⁷ ₈ ³ ₄ 1 7 1 0 0
Typical Attenuation Curve. The U Series is an intermediate grade straight-through absorptive silencer. The U Series utilizes a lower length to diameter ratio. The U Series consists of mild steel construction with primer coated exterior. Attenuation, db 1 0 0 00 1K K K K Octave Band Center Frequency, Hz U Series Straight-Through Absorptive Rotary Silencers ositive Blower Silencers Common Applications intermediate size rotary positive blower inlet centrifugal blower inlet or discharge intermediate size dry vacuum pump discharge gas turbine inlet high-speed centrifugal compressor inlet high frequency noise sources ote: U series standard paint and acoustical packing are suitable for F. 1 7 L H D Absorptive Material Sizes ½" through 1-1/" are constructed with one-piece tapped heads. The tapped opening is approximately flush with the end of the shell. Sizes ½" through " utilize female T pipe connections. Sizes " and " utilize /10 ASI drilled plate flanges. Straight-Through Model U- U- U- U- U- U- U- art --AA --AA --AA -1-AA -1-AA -1-AA -1-AA D L H Weight 1 77 9 1 70 9 70 0 For inlet sizes above " please contact B&W Universal for price and availability.
. Absorptive Rotary ositive Silencers Blower Silencers SU Series Annular Flow SU and SU Series silencers are available in sizes from " through " inlets. For sizes larger than " please contact B&W Universal for price and availability. 1 7 ote: SU Series standard paint and acoustical packing are suitable for F. Common Applications Inlet and discharge of high speed low pressure centrifugal compressors and blowers less than 1 psig Industrial fan inlet and discharge High pressure centrifugal compressors inlet Gas turbine inlet Dry vacuum pump discharge Some low pressure vents less than 1 psig High frequency noise sources Inlet of turbocharged reciprocating engines L H D SU Series The SU Series is a premium grade annular flow absorptive silencer. The design consists of two concentric perforated cylinders lined with acoustical packing. The two concentric cylinders form an annular flow path with blocked line of site to provide full flow area for low resistance. The SU Series comes standard with carbon steel construction and primer coated exterior. All sizes furnished with flanged connections to match #/10# ASI drilling. Absorptive Material SU Series The SU Series is a standard grade annular flow absorptive silencer. The design consists of two concentric perforated cylinders lined with acoustical packing. The two concentric cylinders form an annular flow path with partial blocked line of site to provide full flow area for low resistance. The SU Series comes standard with carbon steel construction and primer coated exterior.
. SU SU Model art D L H Weight SU- SU- SU- SU- SU- SU- SU- SU- SU-1 SU- SU- SU- SU- SU- SU- SU- SU- SU- SU- SU- SU-1 SU- SU- SU- SU- SU- SU- --AA --AA --AA --AA -1-AA -1-AA -1-AA -1-AA -11-AA -1-AA --AA --AA --AA --AA -1-AA --AA -1-AA -1-AA -1-AA -1-AA -11-AA -1-AA --AA --AA --AA --AA -1-AA 1 1 1 1 1 1 7 7 9 91 11 1 9 9 7 7 9 1 1 9 7 1 7 9 0 9 9 0 1 19 90 90 00 0 90 1,00 1,0 1,0,0,00 1 1 0 70 90 0 00 0 90 SU Series Annular Flow Absorptive 1 7 Rotary Silencers ositive Blower Silencers Typical Attenuation Curve SU Series Attenuation, db Typical Attenuation Curve SU Series 1 0 0 00 1K K K K Octave Band Center Frequency, Hz
Babcock & Wilcox Universal 19 Highway 1-1 Stoughton, Wisconsin, U.S.A. 9 hone: +1.0.7 UIVERSAL EERGY EVIROMETAL The information contained herein is provided for general information purposes only and is not intended nor to be construed as a warranty, an offer, or any representation of contractual or other legal responsibility. B&W Universal is a subsidiary of The Babcock & Wilcox Company (B&W). Established in 17, B&W is a global leader in advanced energy and environmental technologies and services for the power, industrial and renewable markets, with operations, subsidiaries and joint ventures worldwide. 17 Babcock & Wilcox Universal, Inc. All rights reserved. For more information or to contact us, visit our website at. E01-0 7J