NOISE ISOLATION EQUIPMENT
NOISE ISOLATION EQUIPMENT
Noise isolation shall be achieved by the following equipment. The Tenderer is required to submit acoustic test reports and all information as required in the Appendix A – Schedule of Technical Data and Guarantee and Appendix B – Calculation Sheet for Silencer/Insulation Performance for the noise isolation equipment offered together with his Tender. Failure to do so shall deem his Tender incomplete and shall cause his Tender
to be rejected for consideration.
3.1 RADIATOR AIR DISCHARGE SILENCERS, AIR INTAKE SILENCERS AND VENTILATION AIR INLET SILENCERS
The silencers shall be of dissipative type and constructed of specially selected high quality materials. Outer casings of silencers shall be made of galvanised steel sheets of thickness not less than 1.2 mm. Beams shall be lock-formed and mastic filled. Tack-welded lap joints are not acceptable due to high air leakage. Internal splitters of rectangular silencer shall be constructed of galvanised steel sheets of minimum 0.7 mm thick and shall have aerodynamically designed bell-mouth entrances with tapered tail sections for minimum static pressure loss. Bull-nosed section of internal splitters must be solid-faced to prevent erosion of acoustical in-fill. Centre pod of conical silencer shall be constructed of minimum 0.7 mm thick
galvanised steel sheets and shall have aerodynamically designed FRP inlet and tall cones. Acoustical in-fill shall be of inorganic high density bonded long stranded rock wool sufficient to obtain the specified acoustic performance and be packed under not less than 5% compression to eliminate voids due to vibration and settling. In-fill material shall be insect, vermin and moisture poof. Silencers using lock-formed joints shall not fail structurally when subjected to a differential air pressure of 1993 Pascal inside to outside of casing. Acoustic louver made of aluminium sheet or rain hood of galvanised steel sheet with bird mesh shall also be provided for the silencers. Junction or penetration between silencer and the walls shall be sealed with airtight with non-setting resilient caulking compound. The silencers shall be tested in an acoustic laboratory and acoustic test report and its attenuation performance shall be submitted to the S.O.’s Representative.
3.2 EXHAUST SILENCERS
Exhaust silencers shall consist of a primary silencer with a secondary exhaust silencer installed in series. The silencers shall be tested in an acoustic laboratory and acoustic test report and its attenuation performance shall be submitted to the S.O.’s Representative. The primary exhaust silencer shall be a multiple chamber reactive type designed for low frequency attenuation. The secondary exhaust silencer shall be straight-through absorptive type for mid to high frequency attenuation and to be installed in series with primary exhaust silencer. Silencer shall be of all welded steel construction finished with high quality aluminium sheets. Acoustical in-fill shall be inorganic high density bonded long stranded rock wool capable of maximum service temperature of 650 degree Celsius. The noise level at the exit of the exhaust system shall not exceed the noise level stated in Section 2.0 – Design Criteria above measured at one meter from the exit of the exhaust system. All supports and hangers for the silencers and exhaust system shall be of hot dipped galvanised steel with spring isolators.
3.3 ACOUSTIC DOORS
Equipment and personnel doors shall be acoustical doors for effective isolation of generator room noise. Acoustic doors shall be constructed from minimum 1.2 mm thick electrogalvanised steel sheet with acoustical in-fill of inorganic high density bonded long strand stranded rock wool sufficient to obtain the specified acoustic performance and be packed under not less than 5% compression to eliminate voids due to vibration and settling. Acoustic door shall be of at least Sound Transmission Class (STC) 46. 20140-10 – Acoustic Measurement of Sound Insulation in Building and of Building Elements: Laboratory Measurement of Airborne Sound Insulation of Small Building Elements, achieving at least STC 46. Acoustic test reports shall be submitted to S.O.’s Representative. If specified, acoustic fire rated door shall be of at least 1½ hours fire rating and of the type approved by Jabatan Bomba dan Penyelamat (JBP) Malaysia. The Tenderer shall submit a copy of approval by JBP together with his Tender. The acoustic fire rated door shall be tested in an independent laboratory in accordance with BS EN 1634-1 – Fire Resistant Test for Doors And Shutter Assemblies, Fire Doors And Shutters, to achieve a fire rating of at least 1½ hours. Fire resistant test reports shall be made available to the S.O.’s Representative for inspection.
The acoustic door assemblies shall consist of steel frame, door-leaf perimeter seal, floor seals, cam-lift hinges, pull handle, push plate and lock-set. Door leaf cladding and all door hardware such as cam-lift hinges, pull handle, push plate and lockset shall be made of stainless steel. Door hardware and seals shall also be for minimum 1½ hours fire rating. Cam-lift hinges used in conjunction with floor seal shall provide continuous
gravity activated compression against floor when door is closed. Raised threshold will not be permitted. The acoustic door shall be anti rust treated and finished externally both sides with decorative colour paints to the colours of the respective walls. The cost, whether or not provided in the Bill of Quantities, shall deem to be included in the Contract.
3.4 WALL AND CEILING INSULATION
In general the walls of the generator room are of 100 mm thick clay bricks walls plastered 20 mm thick both sides. If so required, the internal walls of the generator room shall be acoustically treated with sound absorption material of inorganic high density felted mineral fibre board covered with decorative facings, to achieve noise level outside the generator room not exceeding the noise levels as stated in Section 2.0 – Design Criteria above In the case where the ceiling is not of reinforced concrete slabs, the noise insulation shall be provided, and the ceiling shall be acoustically treated with sound absorption material of inorganic high density felted mineral fibreboard, to achieve at least STC 46. The Electrical Contractor shall be responsible to verify and ensure that the ceiling and associated structures of the generator room/building able to carry the additional loading of such acoustic ceiling treatment installation for the safe intended usage of the generator room. The sound absorption material used shall be of fire-retardant class to the requirement of and approved by JBP Malaysia. The cost for such acoustic treatment for the walls and the ceiling, whether or not provided in the Bill of Quantities, is deemed to be included in the Contract.