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Treatment Strategy

  • PathDirect
  • Receiver

Application Use

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


Acoustical Curtain Systems

Flexible Modular Curtain Systems To Contain and Absorb Noise Without Compromising Access

  Typical BAC-110R HUSH FLEX™ curtain system (ceiling suspended) around a screw machine.  Features include double track sliding panel access, viewing windows and overhead baffles.
Advantages: Applications:
  • Economical alternative to rigid enclosures
  • Easy to install without special tools
  • Maximum application flexibility
  • Allows quick access to equipment for operation and maintenance
  • Washable and steam cleanable
  • Custom designs with standard components
  • Fire safe ratings meeting ASTM E-84, class A
  • Durable construction with good oil and chemical resistance
  • Outdoor/high temperature designs available
  • High noise reduction performance up to 15 dBA with open top designs
  • Can include the support structure, roof panels, air vents and other accessories.
  • Metal working presses and equipment
  • Generators and power equipment
  • Dicers, granulators and pelletizers
  • Compressors and pumps
  • Fans and blowers
  • Paper and corrugation machinery
  • Foundry shakeouts
  • Vibratory screeners and converters
  • Dust collectors
  • Pulverizers
  • Hydraulic units
  • Test areas
  • Plant dividers
  • Movable screens
  • In-wall constructions
  • Chillers and refrigeration equipment
  • VAV boxes
  • Packaged HVAC equipment
  • Screw Machines



About BRD HUSH FLEX™ Curtain Systems:
BRD HUSH FLEX™ curtain systems combine absorber and barrier layers into composite panels that can be readily hung from or mounted to customer supplied pipe, angle iron, strut, track or wood frames.  BRD also offers a 16 gauge track system with all components as needed for a turnkey project.  Twelve gauge and heavy duty structural steel framework are also available.

Several system models are offered in two distinct styles:  the BAC (Barrier/Absorber Composite) and ABAC (Absorber/Barrier/Absorber Composite) models.  The BAC systems are used where maximum abuse resistance is important and on movable panels.  The ABAC systems are used where absorption on the outside of curtains is desired or where the panels are used to separate noise sources on both sides.  For further information see also the section on HUSH QUILT™ composites.

Type BAC Barrier/Absorber Composite panel material.

Type ABAC Absorber/Barrier/Absorber Composite panel material.

CAD Assembly

Drawings Furnished

With Every Order!


Acoustic Performance Test Results

Model No. Thickness (in.) Wt. Lb./Ft.2 Sound Transmission Loss (dB) 1/3 Octave Band Center Frequencies (Hz)
125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 STC
BAC-110R .75-1 1.3 11 11 13 16 19 20 24 25 29 30 30 32 35 35 34 35 27
BAC-210R 1.5-2 1.5 13 16 16 20 22 26 29 33 37 40 44 47 50 51 53 55 32
ABAC-111N 1.5-2 1.5 12 11 13 16 19 22 27 30 36 40 42 44 44 44 44 43 29
ABAC-121N 1.5-2 2.5 19 20 20 22 21 25 28 33 37 40 46 52 56 58 60 61 33
ABAC-R111N 2.2-5 2.6 19 20 19 20 19 24 28 33 38 42 48 53 56 59 61 62 31


Model No. Sound Absorption Data-Absorber Component Random Incident Sound Absorption


  1. Acoustical testing per ASTM C-423-77, C-423-90A; ASTM E-90-75; E-90-90.  Copies available upon request.
  2. Actual noise reduction will vary with application, enclosure design, features and peak frequency of the sound source.


Octave Band Center Frequencies (Hz)
125 250 500 1000 2000 4000 NRC
BAC Products .12 .47 .85 .84 .64 .62 .70
ABAC & 2" BAC Products .07 .27 .96 1.13 1.08 .99 .85


ABAC high temperature 12' high curtains protect a welder from brake and shear noise in a machine shop. Typical double track design sliding panel access for compressor enclosure.


Typical Panel Construction:
  • Factory bound edges
  • No. 5 brass grommets at top for hanging
  • Velcro hook and loop fastening strips on vertical overlapping (2" standard) edges
  • Optional corner strips
  • Top edge reinforcing on BAC styles and when overall panel length dictates for ABAC styles
  • Standard facing is vinyl coated fiberglass cloth good for service up to 180°F
  • Optional silicone coated fiberglass cloth facing for high temperature applications or where there is exposure to UV rays (Temperature range is -90°F to 550°F)
  • Heavy duty edge binding available for sliding panels
  • Standard colors are gray, tan, white and black
Standard Type TC Framing and Hardware Components:


Special lengths of straight track available upon request - 20 ft. maximum.


Double track rails with roller trolley.  Corner rails slide in to seal open ends.


ABAC-111N panel with 4" corner strip hung on roller trolley and track system.





  • Manufactured from 2 1/2" x 2 1/2" x 3/16" tube steel members (oil enamel painted)
  • Best suited for enclosure or barrier wall heights exceeding 10'; mandatory for heights exceeding 12'.
  • Can be used for outdoor applications; larger tube steel members may be required based on final layout and wind exposure.
  • Easy bolt together design simplifies assembly and installation.
  • Standard track channels can be added to cross members where panel mobility is required.
  • Preferred method of panel support and attachment is with STS adjustable clips (illustrated below).
  • Allows for greater column spans; up to 15' for a 14' high curtain system.  Fewer column supports reduces material costs, installation labor and minimizes potential column interferences at floor level.


STS Framing Details
Column Base Plate Detail Base Plate Anchor Detail
STS Adjustable Clip Detail Panel Attachment Detail


Crossbeam End Drilling Details
Long Corner End Short Corner End Mid Column End

Step 1:  Erect Framework

Quick & Easy Installation

Step 2:  Hang HUSH FLEX™ Curtains

Finishing Field Cuts on ABAC-111N Panels


Needed Tools & Materials

  • Utility knife and shears
  • Edge binding trim cloth to match panel quilted facing
  • Tape measure
  • Plier type staple gun
  • Compass or scribe for radius or circular cut-outs
  1. Cut panels with utility knife or shears to fit as snug as possible.  Keep gaps to a minimum.
  2. Fold edge binding material over edges, equal amounts on front and back.  (Note:  A few staples along cut edge will help compress material prior to installing edge binding.)
  3. Staple bind edge binding material to panel, with staples every 2 - 3 inches.


  HUSH FLEX™ Enclosure Access Options

 Infrequent Entry Access

Overlapping (2") Velcro closures are standard for all HUSH FLEX™ systems on maximum 48" centers for ABAC panels or 54" centers for BAC curtains.  This provides quick and easy entry access points around the entire perimeter of the enclosure and at the corners.  Heavy duty edge binding increases panel edge durability where repeated handling is expected.  Applies to fixed and movable suspension/attachment to the support framework.


 Occasional Service/Entry Access

The BRD HUSH FLEX™ curtain system standard framework design is model STC Strut Track Channel with nylon wheel roller trolleys.  When used with double track rail systems, curtain panels can be alternately suspended from the inside and outside track rails.  Single or multiple curtain access clearance can be accomplished by disengaging the Velcro seams of the panel(s) and sliding it/them on the open track.  Variations of this design include track wall extensions, corner radius tracks and triple/quad track layouts.


 Frequent Service/Entry Access

Single or double panel access doors are designed with 8" to 12" of panel overlap at each edge of the required entry/service opening.  This extended overlap compensates for the lack of Velcro to maintain acoustic performance while ensuring ease of movement/door operation.  Sliding door panel features include cloth handles, heavy duty edge binding and optional viewing windows.  When enclosure wall heights exceed 10', independently supported access doors of a more workable 7' to 8' height are recommended.





The swivel and stack hardware system includes a full width top mounted channel support connected to a single suspension steel wheel heavy duty roller trolley.  As pictured above, the single suspension point (top middle of each panel) allows the panel to swivel 90° so that it is perpendicular to the track.  Successive additional panels along the enclosure wall can be swiveled in a similar manner to create a full or partially open area with the panels stacked at one end.  A curtain wall measuring about 20' long can be stacked to expose all but about 18".  The curtain enclosure layout must provide about 2' of clearance on each side of the track in the area where the panels will be stacked/stored.


Curtain Panel
Ventilation Baffle
Rooftop Ventilation
BAC-110R composite material used to form an airflow vent baffle.  Can be used as an intake or discharge (covers cutout in a panel). 16 gauge steel vent baffle with 1" thick faced acoustical foam liner.  Can be used as an intake or discharge (covers cutout in roof panel).
Roof Panel
And Valance
Fixed Mounting
Angle Detail


HUSH FLEX™ Options and Accessories 

  • Laminated facing construction
  • Sliding/retractable roof panels
  • Custom hardware to suit
  • Circular support frame designs
  • Strip curtains for access
  • Heavy duty edge binding for sliding panels
  • Ventilation fans
  • Lighting
  • Windows
  • Accordion fold curtains
  • Access flaps
  • Feed chute openings
  • Portable frames
Temporary Construction Barriers
  • Model EBAC-110N-VCP construction
  • Low cost HUSH FLEX™ construction for projects with typical life span of 3 - 5 years
  • Non-reinforced vinyl barrier
  • 2" thick exterior grade absorber
  • Grommets and Velcro
  • Rated at STC-32 and .85 NRC
  • Contractor supplied framing
  • Can be supplied in roll form or in custom size panels


Guidelines for Outdoor Curtain Systems, Enclosures and Acoustical Barrier Walls

Recommended Exterior HUSH FLEX™ Construction

  • Model EBAC-110R-P
  • RLV-100
  • Vinyl coated polyester absorber facing
  • Tenera thread stitching
  • Exterior grade velcro

Fence Support Structures

Cooling tower curtain system attached to chain link fence Air-cooled screw chiller with HUSH FLEX™ curtain panels attached to chain link fence.
HUSH FLEX™ panels attached to wood planking fence. Close-up of HUSH FLEX™ panels on inside of wood slat fence enclosure.


Masonry/Brick Solid Wall Support Structures
Concrete/stucco wall structure with HUSH FLEX™ panels creates efficient chiller sound enclosure. Brick wall attachment of HUSH FLEX™ panels.
CMU block wall enclosure with HUSH FLEX™ exterior grade curtain panels. HUSH FLEX™ curtain panels attached to inside of existing non-acoustical metal screen walls.
Turnkey STS Structural Tube Steel Systems
STS columns are tied to dunnage steel equipment support platform. Finished enclosure with sliding access panel controls condensing unit noise.