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Treatment Strategy

  • Source Airborne
  • PathDirect

Application Use

  • Industrial In-plant
  • Industrial New Con.
  • OEM
  • Environmental
  • HVAC


Acoustical Lagging Panels

Tight Fitting Acoustical Lagging Panels/System
For Source Treatment On Large Surface Area
Ductwork and Equipment

About BRD HUSH LAG™ Panel Systems:

Typical cutaway of model HLP acoustical lagging panels.

BRD HUSH LAG™ acoustical lagging panels and systems have prefabricated customized multi-layer composite construction.  Composite panel designs utilize absorptive and barrier components to achieve the highest possible noise reduction in a direct attachment source treatment.  The typical panel construction (shown at right) utilizes a steel or aluminum outer skin for strength and durability.  High density acoustic fill may include a layer of HUSH BLOCK™ flexible barrier material for added transmission loss.  The inside retaining screen and impaling clips hold the insulation layers in place.  Typical panel thickness ranges from 2" to 6" depending on the acoustical performance or criteria.

Structural steel angle or channel sub-girts are welded to the equipment or ductwork skin with a minimal number of attachment points to reduce structure-borne noise that can radiate to the panel outer skin.  Sheet metal screws or other anchors are used to attach HUSH LAG™ panels to the sub-girts.  Final installation of flashing and trim at corners and joints covers all exposed fiberglass and edges.  Access doors and removable panel sections can be incorporated.

Advantages: Applications:
  • Finished interior panel surface is not necessary (saves on cost)
  • Construction and panel design flexibility to meet project acoustical performance criteria
  • Meets acoustical and thermal requirements
  • Easy to install according to factory supplied drawings and instructions
  • More economical than freestanding, modular, HUSH GUARD™ traditional enclosures
  • Forced draft and induced draft fans
  • Primary, secondary and seal air fans
  • Scrubber systems
  • Large dust collectors and baghouses
  • Above grade equipment and ductwork
  • Large HVAC & exhaust duct systems
  • Heat recovery steam generators (HRSG)
  • Ductwork connected to large fans, boilers, turbines, dust collectors, incinerators, etc.



COMPLETED FRAME INSTALL PANELS INSTALL FLASHING AND ACCESSORIES Typical installation sequency (at left) and panel attachment details (above) using HUSH LAG™ panels on a fan housing.
Untreated (above left) process ductwork before installation of type HLP HUSH LAG™ acoustical lagging panels (above right).


Power plant turbine inlet ductwork, elbow and silencer showing sub-girt angle locations (at left).  Type HLP-300 panels are attached to the sub-girts (at right).

Standard Panel Designs

Product Thickness Exterior Skin Acoustic Insulation Septum Interior Skin Material/Finish
HLP-300 3" 18 ga. 8 lbs./ft.3 Loaded Vinyl Screen and impaling clips Galvanized steel
HLP-301 3" 18 ga. 8 lbs./ft.3 None Screen and impaling clips Galvanized steel
HLP-302 3" 20 ga. 8 lbs./ft.3 None Vinyl Screen and impaling clips Galvanized steel

Acoustic Performance Data

Product Sound Transmission Loss (dB) Frequency (Hz)
63 125 250 500 1000 2000 4000 8000
HLP-300 8 15 24 28 32 32 40 43
HLP-301 0 6 15 20 22 25 28 31
HLP-302 0 0 9 8 15 10 22 25

Consult BRD for custom panel designs to meet your performance requirements.