SECTION 15920

SOUND ATTENUATORS

PART 1 GENERAL

SECTION INCLUDES

Duct Silencers.

Cross-Talk Silencers.

Acoustic Housings.

Ductwork Lagging.

Acoustical Louvers.

RELATED SECTIONS

Section 07900 - Joint Sealers.

Section 15890 - Ductwork: Connections to silencers.

Section 15910 - Ductwork Accessories: Flexible duct connections.

REFERENCES

AMCA 300 - Test Code for Sound Rating.

AMCA 301 - Methods for Calculating Fan Sound Ratings from Laboratory Test Data.

AMCA 302 - Application of Sound Loudness Ratings for Non-Ducted Air Moving Devices.

AMCA 303 - Application of Sound Power Level Ratings for Ducted Air Moving Devices Recommended Typical dBa Calculation.

ANSI S1.1 - Acoustical Terminology (Including Mechanical Shock and Vibration).

ANSI S1.8 - Preferred Reference Quantities for Acoustical Levels.

ANSI S1.13 - Methods for Measurement of Sound Pressure Levels.

ARI 270 - Sound Rating of Outdoor Unitary Equipment.

ARI 575 - Measuring Machinery Sound Within Equipment Rooms.

ASA 16 (ANSI S1.36) - Survey Methods for Determination of Sound Power Levels of Noise Sources.

ASA 29 (ANSI S1.29) - Measurement and Designation of Noise Emitted by Computer and Business Equipment.

ASA 47 (ANSI S1.4) - Specification for Sound Level Meters.

ASA 49 (ANSI S12.1) - Preparation of Standard Procedures to Determine the Noise Emission from Sources.

ASA 61 (ANSI S12.10) - Computer and Business Equipment.

ASHRAE 68 - Method of Testing In-Duct Sound Power Measurement Procedure for Fans.

ASHRAE Handbook - Systems Volume, Chapter "Sound and Vibration Control".

ASTM E90 - Method for Laboratory Measurement of Airborne Sound Transmission of Building Partitiions.

ASTM E477 - Method of Testing Duct Liner Materials and Prefabricated Silencers for Acoustical and Airflow Performance.

ASTM E596 - Method for Laboratory Measurement of the Noise Reduction of Sound Isolating Enclosures.

NEBB - Procedural Standards for Measuring Sound and Vibration.

SMACNA - HVAC Duct Construction Standards - Metal and Flexible.

DEFINITIONS

Submittals, and Report: Conform to ANSI S1.1.

PERFORMANCE REQUIREMENTS

Maintain sound level of spaces at levels not to exceed those listed below by utilizing acoustical devices as required to achieve specified sound levels.

Maintain rooms at following maximum sound levels, in [Noise Criteria (NC)] [Room Criteria (RC)] as defined by [ASHRAE Handbook.] [ANSI S1.8.]

Private Residences	[25] [30]

Apartments	[30] [35]

Hotels/Motels

Individual rooms/suites	[30] [35]

Meeting/banquet rooms	[30] [35]

Halls, corridors, lobbies	[35] [40]

Service/support areas	[40] [45]

Offices

Executive	[25] [30]

Conference rooms	[25] [30]

Private	[30] [35]

Open-plan areas	[35] [40]

Computer/business machine areas	[40] [45]

Public circulation	[40] [45]

Hospitals and Clinics

Private rooms	[25] [30]

Wards	[30] [35]

Operating rooms	[25] [30]

Laboratories	[30] [35]

Corridors	[30] [35]

Public areas	[35] [40]

Churches	[25] [30]

Schools

Lecture and classrooms	[25] [30]

Open-plan classrooms	[30] [35]

Libraries	[30] [35]

Concert Halls and Legitimate Theatres

Theatre	[20] [25]

Stagehouse	[20] [25]

Trap room	[20] [25]

Orchestra pit	[20] [25]

Rehearsal rooms	[20] [25]

Teaching studios	[25] [30]

Practice rooms	[25] [30]

Ensemble rooms	[25] [30]

Shop	[40] [45]

Recording Studios

Recording room	[15] [20]

Sound Control room	[20] [25]

Other Control rooms	[20] [25]

Movie Theatres	[25] [30]

SUBMITTALS

Submit under provisions of Section [01300.] [_____.]

Shop Drawings: Indicate assembly, materials, thicknesses, dimensional data, pressure losses, acoustical performance, layout, and connection details.

Product Data: Provide catalog information indicating, materials, dimensional data, pressure losses, and acoustical performance.

Samples: Submit [two] [_____] [_____x_____] inch ([_____x_____] mm) in size of cross-talk silencers.

Design Data: Provide engineering calculations, referenced to specifications and [AMCA 301] [AMCA 302] [AMCA 303] [ARI 270] [ASA 49 (ANSI S12.1)] standards indicating that maximum room sound levels are not exceeded.

Test Reports: Indicate [dynamic insertion loss and noise generation values of silencers.] [acoustic housings meet or exceed specified sound transmission loss values.]

Manufacturer's Installation Instructions: Indicate installation requirements which maintain integrity of sound isolation.

Manufacturer's Field Reports: Submit under provisions of Section [01400.] [_____.]

Manufacturer's Field Reports: Indicate installation is complete and in accordance with instructions.

PROJECT RECORD DOCUMENTS

Submit under provisions of Section [01700.] [_____.]

Accurately record actual locations of [cross-talk silencers.] [acoustic housings.] [ductwork lagging.]

QUALITY ASSURANCE

Perform Work in accordance with [AMCA 300] [ANSI S1.13] [ARI 575] [ASA 16 (ANSI S1.36)] [ASA 29 (ANSI S1.20)] [ASA 61 (ANSI S12.10)] standards and recommendations of [ASHRAE 68.] [NEBB.]

Maintain [one] [_____] copy of [each] document on site.

QUALIFICATIONS

Manufacturer: Company specializing in manufacturing the products specified in this Section with minimum [three] [_____] years [documented] experience.

Design application of [duct silencers] [acoustic housings] under direct supervision of a Professional Engineer experienced in design of this work and licensed [at the place where the Project is located.] [in the State of [_______________.]]

REGULATORY REQUIREMENTS

Conform to [applicable] [_______________] code for sound levels at [property line.] [_______________.]

PART 2 PRODUCTS

MANUFACTURERS

[______________________________] Model [_______________.]

[______________________________] Model [_______________.]

[______________________________] Model [_______________.]

Substitutions: Under provisions of Section [01600.] [_____.]

DUCT SILENCERS

Description: Duct section with sheet metal outer casing, sound absorbing fill material, and inner casing of perforated sheet metal; incorporating interior baffles of similar construction. Fabricate in accordance with SMACNA HVAC Duct Construction Standards - Metal and Flexible.

Configuration: Tubular [with] [without] inner casing and liner, [without center body] [with absorptive] [aerodynamically shaped center body with nose cone and truncated tail cone] [splitters with radiused nose and contoured tails], [__________] diameter [as indicated], length [1.5] [2] [3] [4] times diameter.

****** [OR] ******

Configuration: Rectangular with lined splitters with radiused nose and contoured tails, modular [_____] high, [_____] wide, [_____] long.

Materials:

Outer Casing: Minimum [22 gage (0.8 mm)] [20 gage (0.9 mm)] thick galvanized steel stiffened as required, with [mastic filled lock formed] [welded] seams, 2 inch (50 mm)] long, 11 gage (2.9 mm) slip joints on both ends.

Inner Casing and Splitters: Minimum 24 gage (0.6 mm) thick perforated galvanized steel.

Fill: Glass fiber or mineral wool of minimum [4 lb/cu ft (64 kg/cu m)] [3 lb/cu ft (48 kg/cu m)] density.

Fill Liner: [Bonded glass fiber matting.] [1 mil (0.0254 mm) mylar film.]

Rating:

ASTM E477 Insertion Loss and Maximum Generated Noise at [1000 fpm (7 m/sec)] [2000 fpm (10 m/sec)] [4000 fpm (20 m/sec)] Face Velocity:

Octave Band Center Frequency (Hz)

63	125 250	500	1000	2000 4000

Insertion

Loss (dB)	[___] [___] [___] [___]	[___] [___] [___]

Generated

Noise (dB)	[___] [___] [___] [___]	[___] [___] [___]

Static Pressure Drop at [1000 fpm (5 m/sec)] [2000 fpm (10 m/sec)] Face Velocity: [_____] inches wg ([_____] kPa).

Air Tight Static Pressure: [10 inches wg (2.5 kPa)].

Performance: Achieve noise reduction of:

Octave Band Center Frequency (Hz)

63	125 250	500	1000	2000 4000

Insertion

Loss (dB)	[___] [___] [___] [___]	[___] [___] [___]

Model: [_________] manufactured by [_________________.]

CROSS-TALK SILENCERS

Description: Duct sections with sheet metal outer casing, sound absorbing fill material [, and inner casing of perforated sheet metal]; incorporating interior baffles of similar construction. Fabricate in accordance with SMACNA HVAC Duct Construction Standards - Metal and Flexible.

Configuration: Rectangular, lined [with inner casing] with splitters with radiused nosed and contoured tails, [_____] high, [_____] wide, [_____] long.

Materials:

Outer Casing: Minimum [22 gage (0.8 mm)] thick galvanized steel with [mastic filled lock formed] [welded] seams, 3 inch (75 mm)] long, 11 gage (2.9 mm) slip joint on both ends.

Inner Casing and Splitters: Minimum 24 gage (0.6 mm) thick perforated galvanized steel.

Fill: Glass fiber or mineral wool of minimum [4 lb/cu ft (64 kg/cu m)] [3 lb/cu ft (48 kg/cu m)] density.

Fill Liner: [Bonded glass fiber matting.] [1 mil (0.0254 mm) mylar film.]

Rating:

Equivalent STC: [__________.]

Static Pressure Drop at [500 fpm (2.5 m/sec)] [1000 fpm (5 m/sec)] Face Velocity: [_____] inches wg ([_____] kPa).

Model: [_________] manufactured by [_________________.]

ACOUSTIC HOUSINGS

Description: Modular panels, including access doors and windows, nominal 4 inches (100 mm) thick, with filled outer and inner casing. Fabricate and support in accordance with SMACNA HVAC Duct Construction Standards - Metal and Flexible.

Materials:

Outer Casing: Minimum [18 gage (1.2mm)] [22 gage (0.9 mm)] thick galvanized steel stiffened as required, with [mastic filled lock formed] [welded] seams for [internal flange butt] [covering strip butt] [overlapping lip] [tongue and groove] joining.

Inner Casing and Splitters: Minimum 22 gage (0.8 mm) thick perforated galvanized steel.

Fill: Glass fiber or mineral wool of minimum [4 lb/cu ft (64 kg/cu m)] [4-3/4 lb/ cu ft (76 kg/cu m)]

density.

Fill Liner: [Bonded glass fiber matting.] [1 mil (0.0254 mm) mylar film.]

Window: [_____] x [_____] inch ([_____] x [_____] mm) double glazed with 1/4 inch (6 mm) safety glass.

Rating: ASTM E90 sound transmission loss minimum:

Octave Band Center Frequency (Hz)

63	125 250	500	1000	2000 4000

Transmission

Loss (dB)	[___] [___] [___] [___]	[___] [___] [___]

Performance: ASTM E596, achieve A-Scale noise reduction of:

Octave Band Center Frequency (Hz)

63	125 250	500	1000	2000 4000

Insertion

Loss (dB)	[___] [___] [___] [___]	[___] [___] [___]

Model: [_________] manufactured by [_________________.]

DUCTWORK LAGGING

Acoustic Insulation: [2 inch (50 mm)] [__________] thick, 3 to 5 lb/cu ft (50 to 80 kg/cu m) density glass fiber or mineral wool insulation.

Covering: [Sheet lead] [plaster] [or] [gypsum board] with surface weight minimum 4 lb/sq ft (20 kg/sq m).

ACOUSTICAL LOUVERS

Configuration: [8] [12] [___] inch ([200] [300] [___] mm deep louvers with blades on 45 degree slope; sound absorbing fill material, and inner surface of perforated sheet metal, heavy channel frame, birdscreen.

Materials:

Louvers: [16 gage (1.50 mm) galvanized steel] [or] [12 gage (2.50 mm) extruded aluminum], welded assembly, with factory [prime coat] [baked enamel] [color anodized] finish.

Inner Surface: Minimum 24 gage (0.6 mm) thick perforated galvanized steel.

Fill: Glass fiber or mineral wool of minimum [4 lb/cu ft (64 kg/cu m)[ [3 lb/cu ft (48 kg/cu m)] density.

Fill Liner: [Bonded glass fiber matting.] [1 mil (0.0254 mm) mylar film.]

Birdscreen: [1] [1/2] [3/4] inch ([25] [13] [20] mm) square wire mesh.

Mounting: [Interior] [Exterior] [flat flange.] [angle flange.] [Screw holes in jambs.] [Masonry strap anchors.]

Rating:

Insertion loss:

Octave Band Center Frequency (Hz)

63	125 250	500	1000	2000 4000

Insertion

Loss (dB)	[___] [___] [___] [___]	[___] [___] [___]

Static Pressure Drop at [200 fpm (1 m/sec)] [300 fpm (1.5 m/sec)] [400 fpm (2 m/sec)] Face Velocity: [_____] inches wg ([_____] kPa).

Model: [_________] manufactured by [_________________.]

PART 3 EXECUTION

INSTALLATION

Install in accordance with manufacturer's instructions.

Support duct silencers [independent of] [rigidly to] ductwork[.] [with flexible duct connections, lagged with leaded vinyl sheet on inlet and outlet.] Refer to Section [15890.] [15910.]

Install cross-talk silencers in wall with wall penetrations calked. Refer to Section 07900.

Lag ductwork, where indicated by wrapping with insulation and covering. Apply covering to be air tight. Do not attach covering rigidly to ductwork.

Attach ductwork to acoustic louvers with flexible duct connections. Refer to Section 15910.

MANUFACTURER'S FIELD SERVICES

Inspect installation periodically under provisions of Section [01400.] [_____.]

Provide services of [AABC] [NEBB] testing agency to take noise measurement. Use meters meeting requirements of ASA 47 (ANSI S1.4).

After start-up, final corrections and balancing of systems take octave band sound measurements over full audio frequency range in areas adjacent to mechanical equipment rooms, duct and pipe shafts, and other critical locations, as directed.

Provide one-third octave band measurements of artificial sound sources in areas indicated as having critical requirements.

Submit complete report of test results including sound curves.

SCHEDULE

Drawing_Code	SA-1	SA-2	SA-3

Manufacturer

Model

System

Duct Location

Width or inside dia.

Depth or outside dia.

Length

Total air flow

Face Velocity

Air pressure drop

Dynamic insertion loss (dB)

2nd Octave

3rd Octave

4th Octave

5th Octave

6th Octave

7th Octave

8th Octave

END OF SECTION