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Sonic Series acoustic louvre SL4-20C

The Sonic Series acoustic louvre SL4-20C is a 200mm deep acoustic louvre designed to provide controlled airborne sound reduction while maintaining airflow performance. Use it where greater acoustic attenuation is required within a 200mm system depth.

Engineered to balance acoustic attenuation, airflow performance and weather protection, the SL4-20C provides increased airborne sound reduction compared with single-blade configurations of equivalent depth. The chevron blade arrangement delivers higher acoustic performance while maintaining efficient airflow through an optimised free open area.

Product Properties Test Data Technical Information

  • Product name:

    Sonic Series acoustic louvre SL4-20C

  • Weighted Sound Reduction Index (Rw):

    Rw 29 (C −1, Ctr −5) assessed to AS 1191-2002, rated to AS/NZS ISO 717.1

  • Insertion loss:

    23dB (C −1, Ctr −5)

  • Free open area (FOA):

    29%

  • Effective flow area (EFA):

    0.14m² (1000 × 1000mm reference specimen)

  • Discharge coefficient (Cd):

    0.50

  • Airflow classification:

    Class 2 to AS 4740

  • Rain penetration class:

    Class C (overall) / Class B (0 m/s)

  • Fire rating:

    Manufactured from non-combustible materials

  • Test standards:

    AS/NZS ISO 717.1 | AS 4740

  • Typical test specimen:

    1000 x 1000mm

  • Customisation:

    Available in standard module sizes or engineered to project-specific dimensions.

Noise Reduction
Frequency (Hz)-1/3 Octave Noise Reduction
1/3 Octave 1/1 Octave
100 12 12
125 13
160 14
200 20 21
250 22
315 24
400 26 27
500 27
630 29
800 30 30
1000 31
1250 31
1600 31 31
2000 32
2500 32
3150 32 30
4000 31
5000 30
Pressure drop
Face Velocity
(m/s)		 Throat Velocity
(m/s)		 Pressure Drop (Pa) Cd (-)
0.5 2.02 10 0.50
1 4.04 40 0.50
1.5 6.06 91 0.50
2 8.08 162 0.50
2.5 10.10 252 0.50
3 12.12 365 0.50
Free open area (FOA)
FOA Cd EFA Performance Level
29% 0.50 0.14 Class 2
  • Weather performance
    Core Velocity
    (m/s)    		 Penetration
    Rate (L/h.m2)    		 Effectiveness Rain Penetration Class
    0 1.0 0.986 B
    0.5 1.0 0.986 B
    1 1.0 0.986 B
    1.5 2.6 0.965 B
    2 9.4 0.875 C
    2.5 10.4 0.861 C
    3 11.5 0.847 C
    3.5 12.5 0.833 C
  • Sonic Series acoustic louvre SL4-20C datasheet PDF
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  • AcousTech Sonic Series acoustic louvre SL4-20C line drawing PDF
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  • AcousTech Sonic Series acoustic louvre SL4-20C - DWG DWG
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  • AcousTech Sonic Series acoustic louvre SL4-20C - RFA RFA
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