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Sonic Series acoustic louvre SL4-20

The Sonic Series acoustic louvre SL4-20 is a 200mm deep single-blade acoustic louvre designed to provide increased airborne sound reduction while maintaining controlled airflow, with rain resistance assessed to AS 4740.

Acoustic performance has been assessed to AS 1191-2002 and rated in accordance with AS/NZS ISO 717.1. The SL4-20 provides predictable acoustic attenuation for mechanical plant enclosures, façade ventilation openings and industrial plant screening where increased airborne sound reduction is required.

Product Properties Test Data Technical Information

  • Product name:

    AcousTech Sonic Series acoustic louvre SL4-20

  • Weighted Sound Reduction Index (Rw):

    Rw 20 (C −1, Ctr −2) assessed to AS 1191-2002, rated to AS/NZS ISO 717.1

  • Insertion loss:

    14dB (C −1, Ctr −2)

  • Free open area (FOA):

    21%

  • Effective flow area (EFA):

    0.16m² (1000 × 1000mm reference specimen)

  • Discharge coefficient (Cd):

    0.77

  • Airflow classification:

    Class 1 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 8 10
125 11
160 11
200 11 12
250 13
315 15
400 15 16
500 16
630 19
800 20 21
1000 21
1250 22
1600 22 21
2000 22
2500 22
3150 22 22
4000 22
5000 24
Pressure drop
Face Velocity
(m/s)		 Throat Velocity
(m/s)		 Pressure Drop (Pa) Cd (-)
0.5 3.4 12 0.77
1 6.9 48 0.77
1.5 10.3 107 0.77
2 13.7 190 0.77
2.5 17.2 300 0.77
3 20.6 430 0.77
Free open area (FOA)
FOA Cd EFA Performance Level
21% 0.77 0.16 Class 1
  • Weather performance
    Core Velocity
    (m/s)    		 Penetration
    Rate (L/h.m2)    		 Effectiveness Rain Penetration Class
    0 3.6 0.951 B
    0.5 4.2 0.944 C
    1 8.3 0.889 C
    1.5 11.5 0.847 C
    2 12.5 0.833 C
    2.5 13.0 0.826 C
    3 13.5 0.819 C
    3.5 14.6 0.806 C
  • Sonic Series acoustic louvre SL4-20 datasheet PDF
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  • AcousTech Sonic Series acoustic louvre SL4-20 line drawing PDF
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  • AcousTech Sonic Series acoustic louvre SL4-20 - DWG DWG
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  • AcousTech Sonic Series acoustic louvre SL4-10 - RVIT RFA
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