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Suggested
Specifications for Uni-Housing™
HVAC Acoustical Panel Systems
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General
Double-wall
(insulated) acoustical enclosures shall be provided as specified on
drawings. All panels and components shall be prefabricated and supplied
by a nationally-recognized manufacturer with published standards of
construction, assembly, and technical performance. The manufacturer
shall have produced a standardized, prefabricated panel system for
at least 10 years. Construction and performance of the installed system
and components shall conform to all specifications listed in this
document. The system and components shall not be susceptible to damage
from extended exposure to airflow, pressure differentials, vibration,
air temperature, or humidity. |
Joint
Construction
Enclosure
panels shall have either a snap-lock joint construction or a tongue-and-groove
joint construction. Panels with snap-lock joint construction shall
be such that adjacent panels are held together rigidly with an integral,
continuous, self-locking joint on both inside and outside panel surfaces.
Panels with tongue-and-groove joint construction will be held together
with fasteners such as screws. Neither panel types should require
H-connectors, tape, or any other type of additional connectors. |
Panel
Construction
| 1.
All panels shall be 2 or 4 inches thick, as noted on the drawings,
with a solid galvanized steel exterior shell, and a solid or
perforated interior galvanized steel shell as noted on the drawings. |
| 2.
The outer and inner shells shall be tack or spot welded to perimeter
and internal longitudinal steel channels and box-end internal
closures, in such a manner and spacing that the panel assembly
will not fail at the maximum operating loads specified in Structural
Performance. |
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3. The outer shell shall be constructed of galvanized
steel with a minimum 20-gauge thickness. |
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4. The inner shell shall be constructed of galvanized
steel (solid or perforated) with a minimum 22-gauge thickness. |
| 5.
Perforated material shall have a 23 percent open area. |
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6. All perimeter and internal longitudinal steel channel
members shall be constructed of ASTM Type A-653 commercial-quality
galvanized steel with a minimum 18-gauge thickness. |
| 7.
All steel panel surfaces, internal channels, and trim items
shall be fabricated from zinc-coated steel with a dipped galvanized
coating (minimum G-60 coating class as determined by ASTM A-924)
and shall meet all requirements of ASTM A-653 for commercial-quality
galvanized carbon steel. |
| 8.
Each enclosure panel shall be completely filled with acoustical/thermal
insulating material that is noncombustible, inert, mildew-resistant,
and vermin-proof. Insulation shall not settle within the enclosure
panel. No insulating materials shall be used that have a flame
spread greater than 25 or a smoke developed greater than 50. |
| 9.
Where specified on the drawings, septum panels shall consist
of a solid galvanized steel sheet (minimum 20-gauge thickness)
centrally sandwiched between layers of insulating material and
perforated galvanized steel outer sheets (minimum 22-gauge thickness).
The solid steel inner sheet shall be framed and sealed so that
air does not leak through the enclosure when a pressure differential
exists. |
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Components
and Installation
| 1.
All base channels shall be installed on a level concrete curb,
the dimensions of which shall be determined from plan-view shop
drawings of the system provided by the system manufacturer.
Spacing of base channel attachments shall be as outlined in
the manufacturer's standard details of assembly. |
| 2.
All assembly trim items shall be constructed of hot-dipped galvanized
steel (minimum 18-gauge thickness) and furnished in standard
lengths to be field cut to the required dimensions. Spacing
of sheet metal screws, application of duct sealant, and positioning
of trim shall be in accordance with the manufacturer's published
erection and installation details. |
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3. All mechanical joints and external trim items shall
be sealed with a UL-Classified duct sealant in accordance with
Section 4 or 5. In order to show that joints have been sealed
properly, enough sealant shall be used so that excess sealant
is extruded from all completed external joints. |
| 4.
For enclosures to be installed indoors, joints and trim shall
be sealed with United Duct Sealer (Water Based), formulated
to withstand temperatures from -25°F to +200°F. Sealant
shall be formulated such that surface preparation or solvent
cleaning is not necessary. Sealant shall have a UL Classification
marking with flame spread of 5 and smoke developed of 0 when
applied to 18-gauge galvanized steel or inorganic reinforced
cement board, both at a coverage of 31 square feet per gallon.
Sealant shall exceed 500 hours without becoming brittle under
ASTM-D572 test conditions (oxygen bomb). |
| 5.
For enclosures to be installed indoors and outdoors, joints
and trim shall be sealed with UNI-WEATHER solvent-based duct
sealant that is a neoprene-phenolic mastic formulated to withstand
temperatures from -20°F to +300°F. Sealant shall be
formulated such that surface preparation or solvent cleaning
is not necessary. Sealant shall have a UL Classification marking
with a flame spread of 5 and smoke developed of 0 when applied
to 18-gauge galvanized steel and a flame spread of 5 and smoke
developed of 5 when applied to inorganic reinforced cement board,
both at a coverage of 53 square feet per gallon. Sealant shall
exceed 1,000 hours under ASTM-D572 test conditions (oxygen bomb)
without becoming brittle and 500 hours in QUV accelerated-exterior-aging
apparatus without degradation (under ASTM-C732 test conditions). |
| 6.
Acoustical personnel access doors shall be provided where specified
on drawings and shall be 24 inches wide by 60 inches high unless
otherwise indicated. All doors shall be the same nominal thickness
as the adjacent panels. All access door panels and doors shall
be constructed with an 18-gauge solid inner and outer shell.
Each door shall have a minimum of two ball-bearing hinges and
two wedge-lever door latches. All levers shall be installed
to open against the air pressure differential. Doors shall seat
against neoprene gasket materials, installed around the entire
perimeter of the door frame in such a manner that door operation
will provide direct compression with no sliding action between
the door and gasket. |
| 7.
Where shown on drawings, acoustical doors shall be furnished
with windows, which are composed of double-glazed layers of
wire-reinforced safety glass, separated by an air space, and
sealed against acoustical and air leakage by interior and exterior
rubber seals. Windows shall be 12 inches wide by 12 inches high
unless otherwise indicated. |
| 8.
Openings for pipe and conduits shall be field cut to ensure
proper positioning. All framing members, collars, and bellmouth
fittings shall be insulated, welded, and sealed according to
the manufacturer's published installation details. |
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Structural
Performance
| 1.
The entire enclosure shall be designed by the manufacturer to
be self supporting. Where roof spans and wall loadings require
additional structural strength, it shall be provided by heavier
panel skins, additional internal longitudinal reinforcing members,
or additional structural members and necessary supporting pipe
columns. The installer shall furnish and install all structural
members and pipe columns according to the drawings and published
installation details provided by the manufacturer. |
| 2.
The finished enclosure shall be able to withstand a positive
internal static pressure of ( ) inches wg and a negative internal
static pressure of ( ) inches wg. Installations subjected to
the effects of weather shall be able to withstand a wind loading
of ( ) pounds per square foot. |
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3. Under the conditions specified in the previous section,
the assembled structure shall not exhibit any panel joint deflections
in excess of L/200, where L is the unsupported span length of
any panel section within the completed enclosure. |
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Acoustical
Performance
| 1.
The manufacturer shall provide certified testing data obtained
from an acoustical laboratory, listing sound absorption and
transmission loss characteristics of the enclosure. When requested
by the engineer, the manufacturer shall arrange to have a copy
of all pertinent acoustical laboratory reports forwarded directly
from the laboratory to the engineer. |
| 2.
When tested according to ANSI/ASTM Standard C423 or a subsequent
version of the standard, the enclosure shall have minimum sound
absorption coefficients, as shown in the table below, in the
1/3 octave band center frequencies. The coefficients used shall
be those reported by the acoustical laboratory. |
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Sound
Absorption Coefficients
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| Octave
Band (Hz) |
125
|
250
|
500
|
1,000
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2,000
|
4,000
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NRC
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|
4-inch panel construction |
0.63
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1.09
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1.17
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1.08
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1.03
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0.97
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1.09
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| 2-inch
panel construction |
0.22
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0.64
|
1.06
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1.06
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0.98
|
0.87
|
0.94
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| 3.
When tested according to ASTM E90 or a subsequent version of
this standard, the enclosure panel shall have minimum airborne
sound transmission losses in the combined full octave band center
frequencies as listed below: |
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Sound
Transmission Losses
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| Octave
Band (Hz) |
125
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250
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500
|
1,000
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2,000
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4,000
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STC
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| for
4-inch panels |
16
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24
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35
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45
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53
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58
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37
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| for
2-inch panels |
18
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21
|
29
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38
|
49
|
55
|
33
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Thermal
Performance
| 1.
Insulating materials used in all prefabricated enclosure panels
shall have the following maximum thermal conductances at a mean
temperature of 75°F: 0.06 BTU per hour per square foot per
°F (for 4-inch panels) and 0.12 BTU per hour per square
foot per °F (for 2-inch panels). |
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