TECHNICAL SPECIFICATION FOR ACOUSTIC ENCLOSURE
As per CPWD norms, restriction has been imposed for new DG Sets upto 1000 KVA for noise level. Therefore, in
terms of these norms, acoustic enclosure should be type tested at the climatic conditions specified in though
one of the authorized laboratory.
Installation.
Acoustic enclosures are supplied with built in Anti Vibration Mountings (AVMs). As such Gen Set can be installed
directly on the level surface.
Exhaust piping outlet should not be turned towards window/ventilator of home or occupied building. Provision of
rain cap should be ensured.
Service Accessibility.
Genset/Engine control panel should be visible from outside the enclosure.
Routine/periodical check on engine/alternator (filter replacement and tappet setting etc) should be possible
without dismantling acoustic enclosure.
For major repairs/overhaul, it may be required to dismantle the acoustic enclosure.
Sufficient space should be available around the Genset for inspection and service.
General Design Guidelines.
To avoid re-circulation of hot air, durable sealing between radiator and canopy is must.
Ventilation fans are must for the Gensets cooled by heat-exchanger/cooling tower system.
Exhaust piping inside the enclosures must be lagged (except below).
Temperature rise inside the enclosure should not be more than 5ºC for maximum ambient above 40º C and it
should be below 10º C for ambient below 40º C.
There should be provision for oil, coolant drain and fill. Fuel tank should have provision for cleaning.
Service Accessibility.
Genset/Engine control panel should be visible from outside the enclosure.
Routine/periodical check on engine/alternator (filter replacement and tappet setting etc) should be possible
without dismantling acoustic enclosure.
For major repairs/overhaul, it may be required to dismantle the acoustic enclosure.
Sufficient space should be available around the Genset for inspection and service.
General Design Guidelines.
To avoid re -circulation of hot air, durable sealing between radiator and canopy is must.
Ventilation fans are must for the Gensets cooled by heat-exchanger/cooling tower system.
Exhaust piping inside the enclosures must be lagged (except below).
Temperature rise inside the enclosure should not be more than 5ºC for maximum ambient above 40º C and it
should be below 10º C for ambient below 40º C.
There should be provision for oil, coolant drain and fill. Fuel tank should have provision for cleaning.
Specifications for Acoustic Enclosure.
The acoustic enclosure shall be designed and manufactured confirming to relevant standards suitable for out
door installation exposed to weather conditions, and to limit overall noise level to 75 dB (A) at a distance of 1
mtr. from the enclosure as per CPCB norms under free field conditions.
The construction should be such that it prevents entry of rain water splashing into the enclosure and allows free
and quick flow of rain water to the ground in the event of heavy rain. The detailed construction shall confirm to
the details as under:-
The enclosure shall be fabricated out of the CRCA sheet of thickness not less than 1.6 mm on the outside cover
with inside cover having not less than 0.6mm thick perforated powder coated CRCA sheet.
The hinged doors shall be made from not less than 16 SWG (1.6 mm) thick CRCA sheet and will be made air tight
with neoprene rubber gasket and heavy duty locks.
All sheet metal should be powder coated.
Th e enclosure should be powder coated.
The enclosure should accommodate the daily service fuel tank of the DG Set to make the system compact. There
should be provision of gauge, which should show the level of the fuel even when the DG set is not running. The
gauge should be calibrated. The fuel tank should be filled from the outside as in automobiles and should be with
a lockable cap.
The batteries should be accommodated in the enclosure in battery rack.
The canopy should be prov ided with high enclosure temperature safety device.
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The acoustic lining should be made up of high quality insulation material i.e. glass/mineral wool of minimum 50 mm
thickness up to 500 KVA capacity and 75 Kg/cubic meter to 100 Kg/cubic meter for sound absorption as per
standard design of manufacturer’s to reduce the sound level as per the CPCB norms. The insulation material shall
be covered with fine glass fiber cloth and would be supported by perforated MS sheet duly powder coated.
The enclosure shall be provided with suitable size and No. of hinged type doors along the length of the enclosure
on each side for easy access inside the acoustic enclosure for inspection, operation and maintenance purpose.
Sufficient space will be provided inside the enclosure on all sides of the DG set for inspection, easy maintenance
and repairs.
The canopy should be as compact as possible with good aesthetic look.
The complete enclosure shall be of modular construction.
The forced ventilation shall be as per manufacturer design using either engine radiator fan or additional blower
fan(s). if the acoustic enclosure is to be provided with forced ventilation then suitable size of axial flow fan
(with motor and auto-start arrangement and suitable size axial flow exhaust fan to take the hot air from the
enclosure complete with necessary motors and auto start arrangement should be provided. The forced
ventilation arrangement should be provided with auto stop arrangement to stop after 5 minutes of the stopping
of DG Sets.
The acoustic enclosure should be suitable for cable connection/connection through bus trunking. Such
arrangement on acoustic enclosure should be water proof and dust-proof confirming to IP-65 protection.
Acoustic Panels and Enclosures
A. General
Furnish and install Price Acoustic Panels and Enclosures of the sizes, configuration
, and performance as described on plans and/or schedules.
Enclosures will include, as required, acoustical panels, trims and mounting channels,
sealant, hardware, doors, and assembly drawings supplied
by manufacturer for on-site assembly by others.
1. Performance
Panel performance characteristics, including transmission loss and absorption coefficient,
shall be attained through testing in accordance with
the ASTM E90 and ASTM C423 test standards.
2. Submittal
Manufacturer’s performance data including transmission loss (STC) and sound absorption
coefficient (NRC) shall be provided and shall be
obtained in accordance with ASTM E90 and ASTM C423 test standards. Submittals shall include
dimensions, openings, access door details,
construction materials, material finishes, assembly instructions, and installation details.
B. Construction
Panels shall be tongue and groove construction an shall consist of 18 gauge solid steel skin,
22 gauge perforated steel liner, 18 gauge full depth
splitters spaced maximum of 16” apart, and absorptive acoustic fiberglass media.
Acoustic Panels: QLP2, QLP4, QLP6
1. Acoustic Media
Acoustic media shall be shot-free inorganic glass fiber with long, resilient fibers, bonded
with thermosetting resin. Glass fiber shall be packed
with a minimum 10% compression to eliminate voids and settling; density shall be consistent
with that used to generate cataloged test data.
2. Combustion Ratings
Combustion ratings for acoustic media shall be equal to or less than the combustion ratings
noted below when tested in accordance with ASTM
E84, UL723 and NFPA255.
Flame Spread Classification: < 25
Smoke Development Rating: < 50
