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WSA/D1051 Rev B/2002 Section 15071/1 Silencers/Acoustic Treatment

SECTION 15071SILENCERS/ACOUSTIC TREATMENT

REVISION HISTORY

B 08.07.02 RevisionsRichardSmith

SteveKing

RichardSmith

A 17.06.01 General RevisionsRichard

Smith

Steve

King

Richard

Smith

0 12.06.01 First IssueRichardSmith

SteveKing

RichardSmith

Rev Date Description Prepared

by

Checked

by

Authorised

by

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1 GENERAL

1.1 SECTION INCLUDES

1.1.1 Include the General Conditions of the Contract as part of this section.

1.1.2 The Contractor shall become familiar with other sections of the Specifications affecting workof this trade.

1.1.3 Furnish all labour, materials, plant, equipment and appliances and perform all necessary

operations required to execute the work of this section.

1.1.4 This section describes the requirements for silencers and acoustic treatment for air-

conditioning and ventilation systems.

1.2 RELATED SECTIONS

1.2.1 This schedule is intended to be used as a helpful indication of the related sections within the

Project Specifications. It is not necessarily comprehensive or complete and it is theContractor's responsibility to ascertain all applicable sections required to understand the full

Scope of Works intended.

15076 Painting and Anti Corrosion

15720 Air Handling Units

15730 Unitary Air Conditioning

15815 Ductwork and Accessories

15830 Fans

1.3 REFERENCES

1.3.1 The minimum standards for products specified in this section shall be those standards referred

to or relevant BSI standards.

1.4 SUBMITTALS FOR REVIEW

1.4.1 Section 01300 - Submittals.

1.4.2 Submit samples, specifications, engineering calculations, catalogue cut sheets, description of

product and installation method in accordance with the Contract Documents. Submissions

shall indicate all dimensions, details of construction, details of installation, relation and

connections with adjoining work.

1.4.3 Submit calculations verifying that proposed silencers and acoustic treatment will ensure

design noise level targets are not exceeded.

1.4.4 Provide certified insertion loss data in accordance with BS 4718. Provide generated sound

power levels with insertion loss data.

1.4.5 Where equipment is manufactured in modules ensure performance ratings apply to complete

unit.

1.5 QUALITY ASSURANCE

1.5.1 Perform Work in accordance with relevant British Standards and industry standard codes.

1.6 QUALIFICATIONS

1.6.1 The specialist employed to provide acoustic products shall have successfully supplied similar

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products in the Muscat area for the last five years.

1.7 MOCK-UP

1.7.1 No requirement

1.8 ENVIRONMENTAL REQUIREMENTS

1.8.1 Acoustic products shall be suitable for the environment in which they are installed and for the

air that flows through them.

1.8.2 The external environment is hot (up to 52C), humid (up to 32C saturated and moisture

contents up to 0.030 kg/kg), dusty (up to 70mg/m) and saline (within 200m of the

shoreline).

1.9 WARRANTY

1.9.1 Section 01740 - Warranties and Bonds.

2 PRODUCTS

2.1 APPROVED MANUFACTURER OR PRODUCT

2.1.1 No particular reference

2.2 PRODUCT REQUIREMENTS

2.2.1 NOISE

Plant and equipment shall be selected and installed to ensure that the noise level in the

spaces served, in any adjacent rooms or buildings and within plant rooms does not

exceed the indicated maximum acceptable noise rating (NR)

2.2.2 NOISE INSULATION (AIRBORNE NOISE)

Attenuators and other noise control equipment shall be selected and installed to achieve

the stated noise ratings with minimum resistance to airflow. Fire properties of sound

absorbent materials shall be in accordance with Section 15080 Thermal Insulation of

this specification. Sound absorbent material that contain and/or require the use of CFCs

in their manufacture shall not be used.

Factory-fabricated attenuators shall be tested in accordance with BS 4718.

2.2.3 DIRECTION OF FLOW:

Clearly mark direction of airflow on silencers.

2.2.4 FIRE PROPERTIES, BUILDING REGULATIONS, CLASS O:

Use non-flammable adhesives. Ensure that all insulating materials and coverings are to

Class O surface rating of Building Regulations.

2.2.5 CIRCULAR SILENCERS - CASING TO DW 144 WITH INTERNAL FLANGES:

Provide circular silencers compatible with ductwork installation. Provide infill that is inert,

fire proof, inorganic, vermin proof, non-hygroscopic.

2.2.6 RECTANGULAR SILENCERS - CASING TO DW144 WITH LOW LOSS FAIRINGS AND EXTERNAL

FLANGES:

Provide rectangular silencers compatible with ductwork installation. Provide infill that isinert, fire proof, inorganic, vermin proof, non-hygroscopic.

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Construct splitters with low loss fairings.

Construct casing to DW144 with external flanges drilled for bolting to counter flanges on

adjacent plant or ductwork.

2.2.7 RECTANGULAR SILENCERS - CASING TO DW144 WITH LOW LOSS FAIRINGS AND WITHIN

AHUs:

Provide rectangular silencers compatible with AHU construction. Provide infill that is inert,fire proof, inorganic, vermin proof, non-hygroscopic.


Install splitter within the double skinned AHU structure.

2.2.8 ACOUSTIC SPLITTERS WITH LOW LOSS FAIRINGS:

Mount splitters vertically or horizontally and fix splitters as shown on drawings.

Construct splitters to ensure that infill is retained and individual acoustic integrity is

maintained.


Provide additional stiffening on horizontally mounted splitters.

Provide infill that is inert, fire proof, inorganic, vermin proof, non-hygroscopic.

Material : Non-combustible mineral wool or glass fibre with minimum density 48 kg/m3.

2.2.9 AIR TRANSFER/CROSS TALK ATTENUATORS WITH SPIGOT ENDS:

Provide attenuators for air transfer and cross talk applications. Provide lining that is inert,

fire proof, inorganic, vermin proof, non-hygroscopic.

Construct casing with lock-formed longitudinal joints, mastic sealed.

Provide plain spigot ends for connection to adjacent ductwork.

Fixing : Interface with building components as indicated.

2.2.10 CIRCULAR AND RECTANGULAR ATTENUATORS - GENERAL

Casings shall be of not less than 0.8mm thickness galvanised mild steel sheet. Joints and

seams shall be designed and constructed to minimise air-leakage by use of mastic or

other suitable sealing method. End flanges shall be welded to the casings with fixing

details and construction methods in accordance with HVCA Specification DW/144.

Welding areas shall be cleaned and coated with zinc-rich paint.

Acoustic material must not break up erode or migrate at up to and including 100 percent

relative humidity. An impervious envelope shall be fitted over the following acoustic fill:

Mineral fibre insulation.

Open-cell acoustic/thermal foam insulation that is not supplied complete with an

inherent PVC sprayed vapour barrier or flexible polyurethane foam.

Inspection covers, in accordance with section - Ductwork + Ductwork Accessories of

this specification, shall be provided at both ends of attenuators.

The dynamic insertion loss of attenuators shall include the effect of any facing materials.

Vapour barriers which are not an inherent part of the acoustic material, shall be of

minimum thickness not exceeding 0.07mm and shall be installed unstressed. The

material shall be inherently non-combustible and limit the surface spread of flame to Class

0 when tested in accordance with BS 476: Part 7 and shall not emit toxic or hazardous

fumes if ignited. Membranes used shall be suitably supported and fixed. Any loss of

acoustic performance due to this treatment will be deemed to be accommodated in this

overall performance of the noise control equipment selected by the Contractor.

Splitter elements in straight rectangular attenuators shall stand vertically, and shall be

tight-fit within the casing. L-section and T-section splitter attenuators shall be fitted

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perpendicular to the plane of the bend. Where splitter elements are horizontal, e.g. in

ceiling spaces, adequate support and retention of acoustic infill must be provided.

2.2.11 KITCHEN EXTRACT SILENCERS

Silencers on kitchen extract systems shall have casings manufactured so that they are

fire proof to a standard to match the ductwork system in which they are installed.

Acoustic media shall be hermetically bagged with Melanix or equivalent.

2.2.12 ACOUSTIC LININGS, PERFORMANCE TO BS EN 20354:

Line internal surfaces of ducts as described in DW 144 Part 7, Section 29. Provide lining

that is inert, fire proof, inorganic, vermin proof, non-hygroscopic.

Material - polyurethane foam.

Performance : Minimum random incidence absorption coefficients in accordance with BS

EN 20354, as indicated.

Protect lining against product migration and erosion.

Linings shall not reduce required airway dimensions.

No lining shall be installed within 1m of any fire damper.

2.2.13 ACOUSTIC INSULATION: Material

- Lightweight resilient glass fibre or mineral wool held in place with wire mesh.

Casing

- Ensure casing is continuous over duct length. Isolate casing from ductwork. Encase

with material with mass of not less than 10 kg/m2.

2.2.14 ACOUSTIC INSULATION FLEXIBLE SYSTEM:

Continuous quilted glass fibre mat with sandwich layer of lead, minimum 1mm thick, with

mass of 7 kg/m2. Ensure surface finish complies with BS 476 Part 7, Class 1. Overlap and

seal all joints with adhesive and external reinforcing tape.

2.2.15 PLENUMS:

Provide plenum constructed using acoustic panels in positions indicated. Joint panels with

seals to match performance of panels. Provide infill that is inert, fire proof, inorganic,

vermin proof, non-hygroscopic.

Material - polyurethane foam.

Performance

- Minimum random incidence absorption coefficients in accordance with BS EN 20354,

as indicated.

2.2.16 ACOUSTIC FLEXIBLE DUCT CONNECTORS:

Provide acoustic flexible duct connectors in accordance with DW144 Part 7, Section 25.

2.2.17 ACOUSTIC LOUVRES WITH INFILL: Performance

Provide certified acoustic performance data measured in accordance with BS EN ISO

140-3.

Ensure louvre withstands specified wind loads and prevent ingress of rain.

Construction

Construct louvre frame and aerodynamically profiled louvre blades from galvanized

mild steel or aluminium as appropriate. Provide integral drainage channels.

Provide acoustic infill which is inert, fire proof, inorganic, vermin proof and non-

hydroscopic.

Retain infill on louvre blades by perforated sheet of galvanized mild steel or

aluminium as appropriate.

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Screen

Fit a bird-screen using mesh no coarser than 12mm, across inside face of louvres.

Quality assurance

Ensure manufacturers are a firm of Assessed Capability to BS EN ISO 9001 and

produce louvre to relevant Quality Assessment schedule.

2.2.18 ACOUSTIC ENCLOSURES

Where indicated, an acoustic enclosure shall be provided to isolate the noise producing

equipment from the room in which it is installed. The required noise reduction or the

maximum permitted ambient noise rating (NR) shall be as indicated. Removable panels

shall be give access to items requiring cleaning, adjustment, replacement and other

maintenance. Where enclosures are designed for personnel access, internal lighting and

viewing panels shall be provided. Access doors shall be openable from both sides.

The enclosure shall be isolated from the noise producing equipment. The enclosure shall

also be isolated from the building structure.

Provisions shall be made to dissipate heat emitted from the noise-producing equipment

where necessary.

3 EXECUTION

3.1 EXAMINATION

3.1.1 Verify site conditions under provisions of Section 01400.

3.1.2 Before ordering any materials / commencing work verify that building structure associated

with the system is within tolerance and take full account of shape configuration and material

properties of the str ucture.

3.2 PREPARATION

3.2.1 No specific requirements.

3.3 HANDLING AND STORAGE

3.3.1 Deliver component parts to site, completely identified in accordance with shop and certified

drawings prepared for this work. Store in accordance with manufacturer's instructions, above

ground, properly protected from the weather and construction activities.

3.4 FABRICATION

3.4.1 All alternatives shall be fabricated and the manufacturers works.

3.5 INSTALLATION

3.5.1 Before beginning installation in any area, examine all parts of the adjoining work into which

applicable work is to be placed. Should any conditions be found which would prevent the

proper execution of the work, installation shall not proceed in that area until such conditions

are corrected by the contractor.

3.5.2 GENERAL

Install acoustic treatment equipment in positions indicated, in accordance with

manufacturers instructions.

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3.5.3 FIXING OF THERMAL AND ACOUSTIC LININGS

Insulation materials shall accurately fit the internal surfaces of the duct. The insulation

shall be fixed using adhesive spread over the entire surface, supplemented by piercing

fasteners as necessary, finished flush with the insulation surface. Particular care shall be

taken to ensure that the edges of all internal insulating materials, whether exposed, or

butted against similar edges, are sealed and secured to the internal surfaces of the duct.

In addition to adhesive and piercing fasteners, thermal and/or acoustic insulation shall be

retained in position as follows:

Foam insulation shall be secured to the duct with angle brackets or straps at corners

and elsewhere as required.

Mineral fibre insulation shall be contained behind securely fixed perforated metal

enclosures.

Airtight sleeves to bridge insulation at perforations shall be provided in accordance with

section 15720 Air Handling Units of this specification.

3.5.4 SUPPORTS:

Supply steel section supporting frames or brackets where silencers are fixed to the walls

of air chambers.

3.5.5 ACOUSTIC LININGS:

Where personnel access is provided, protect acoustic linings to prevent damage.

3.5.6 SOUND PRESSURE LEVEL READINGS:

Measure sound pressure levels at the positions indicated using equipment in accordance

with IEC 179.

3.6 FIELD QUALITY CONTROL

3.6.1 Provide field quality control under provisions of Section 01400 - Quality Control.

3.7 CLEANING

3.7.1 Section 01710 - Cleaning installed work.

3.7.2 Remove labels after Work is complete.

3.8 PROTECTION OF FINISHED WORK

3.8.1 Protect work under provisions of Section 01710.

3.9 STANDARD SPECIFICATION

3.9.1 This standard specification is intended to be used as a helpful indication of work within this

section. It is not necessarily comprehensive or complete and it is the Contractor 's

responsibility to ascertain and complete the full works intended and as shown within the

drawings, specification and Contract or thereby implied.

END OF SECTION