Acoustic Window SpecificationNoise-Lock® W-47ConstructionSteel sub frame – Each frame to be fabricated from 2.0mm thick steel sheet manufactured to suit a minimum wall thickness of 100mm (4”). Frames are to be acoustically de-coupled to prevent direct transfer of sound and vibration. Based on vertical panes as standard with options available for angled panes, please contact IAC for more information.

AbsorptionInternal reveals to be acoustically treated with absorbent material, nylon finished black impregnated Polyurethane Foam 75-95kg/m3. Flame retardant BS:476 Part 6, Class 0 and BS:476 Part 7, Class 1.

GlassDouble glazed comprising two panes of 6.4mm laminated safety glass, seated within a 2.0mm thick steel frame, in combination with a minimum of 100mm (4”) thick wall.

Colour / FinishesSteel sub-liners and other internal steel parts to be polyester powder painted to standard RAL 9005 matt finish. External steel capping frames to be supplied to a standard RAL finish from a wide range of stocked colours. Additional colours are available at extra cost.

One-Way Viewing (if applicable)One way viewing windows operate on a room-room light differential of 7:1 i.e. test rooms needs to be considerably brighter than observation rooms. A specialist contractor shall apply such a film and it is advisable to fit once all construction works are complete on site. Other options for one-way viewing such as electronic switchable laminated glass with liquid crystal film are available on request.

Construction / Performance ConsiderationsFrames designed to suit a minimum wall thickness of 100mm (4”). It is possible to provide this high performance with a thinner wall; however glass thickness will increase by acoustic calculation to compensate for a reduction in air gap. All performance data is modelled using algorithms derived from actual laboratory testing on a range of double glazed window configurations with varying air gap, glazing thicknesses and acoustic ratings between Rw47 and Rw68. To obtain the maximum acoustic performance from IAC Noise-Lock® windows the host wall must have a transmission loss equal or better than the selected window unit and obvious leaks and other transmission paths that could give rise to noise flanking or cross-talk should be eliminated or suitably treated.

Acoustic RatingRw (C; Ctr) 47 (-2; -7) dB to achieve minimum R’w45dB once installed (subject to flanking).STC-46(dB) to achieve minimum NIC 44 once installed (subject to flanking).Certified laboratory performance using standard 100mm (4”) wall thickness arrangement as follows:

Frequency (Hz) 50 63 80 100 125 160 200 250 315 400 500 630 800 1k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k

1/3 Octave Sound Transmission Loss (dB)

20 23 18 26 31 30 31 36 39 41 46 48 49 54 57 59 51 56 62 60 71

Frequency (Hz) 63 125 250 500 1k 2k 4k

Full Octave Sound Transmission Loss (dB)

20 28 34 44 52 54 63