HomeMy WebLinkAbout23 31 13 - Metal DuctsBEARDSLEY DESIGN ASSOCIATES
CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 1 OF 14
NOVEMBER 2, 2012
SECTION 233113 METAL DUCTS
PART 1 GENERAL
1.1 SUBMITTALS
A. Product Data: Provide for each type of the following products:
1. Liners and adhesives.
2. Sealants and gaskets.
B. Provide Shop Drawings as Follows:
1. Fabrication, assembly, and installation, including plans, elevations,
sections, components, and attachments to other work.
2. Factory4 and shop4fabricated ducts and fittings.
3. Duct layout indicating sizes, configuration, liner material, and static4
pressure classes.
4. Elevation of top of ducts.
5. Fittings.
6. Seam and joint construction.
7. Penetrations through fire4rated and other partitions.
8. Equipment installation based on equipment being used on Project.
9. Locations for duct accessories, including dampers, turning vanes, and
access doors and panels.
10. Hangers and supports, including methods for duct and building
attachment and vibration isolation.
C. Field quality4control reports.
1.2 QUALITY ASSURANCE
A. Welding Qualifications: Qualify procedures and personnel according to
[AWS D1.1/D1.1M, "Structural Welding Code 4 Steel," for hangers and
supports.] [AWS D1.2/D1.2M, "Structural Welding Code 4 Aluminum," for
aluminum supports.] [AWS D9.1M/D9.1, "Sheet Metal W elding Code," for
duct joint and seam welding.]
B. Welding Qualifications: Qualify procedures and personnel according to the
following:
1. AWS D1.1/D1.1M, "Structural Welding Code 4 Steel," for hangers and
supports.
2. AWS D1.2/D1.2M, "Structural Welding Code 4 Aluminum," for aluminum
supports.
3. AWS D9.1M/D9.1, "Sheet Metal Welding Code," for duct joint and seam
welding.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 2 OF 14
NOVEMBER 2, 2012
C. ASHRAE Compliance: Applicable requirements in ASHRAE 62.1, Section 5 4
"Systems and Equipment" and Section 7 4 "Construction and System Start4
Up."
D. ASHRAE/IESNA Compliance: Applicable requirements in
ASHRAE/IESNA 90.1, Section 6.4.4 4 "HVAC System Construction and
Insulation."
PART 2 PRODUCTS
2.1 PERFORMANCE REQUIREMENTS
A. Structural Performance: Duct hangers and supports shall withstand the
effects of gravity loads and stresses within limits and under conditions
described in SMACNA's "HVAC Duct Construction Standards 4 Metal and
Flexible".
B. Airstream Surfaces: Surfaces in contact with the airstream shall comply with
requirements in ASHRAE 62.1.
2.2 SINGLE4WALL RECTANGULAR DUCTS AND FITTINGS
A. General Fabrication Requirements: Comply with SMACNA's "HVAC Duct
Construction Standards 4 Metal and Flexible" based on indicated static4
pressure class unless otherwise indicated.
B. Transverse Joints: Select joint types and fabricate according to SMACNA's
"HVAC Duct Construction Standards 4 Metal and Flexible," Figure 241,
"Rectangular Duct/Transverse Joints," for static4pressure class, applicable
sealing requirements, materials involved, duct4support intervals, and other
provisions in SMACNA's "HVAC Duct Construction Standards 4 Metal and
Flexible."
C. Longitudinal Seams: Select seam types and fabricate according to
SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible,"
Figure 242, "Rectangular Duct/Longitudinal Seams," for static4pressure class,
applicable sealing requirements, materials involved, duct4support intervals,
and other provisions in SMACNA's "HVAC Duct Construction Standards 4
Metal and Flexible."
D. Elbows, Transitions, Offsets, Branch Connections, and Other Duct
Construction: Select types and fabricate according to SMACNA's "HVAC
Duct Construction Standards 4 Metal and Flexible," Chapter 4, "Fittings and
Other Construction," for static4pressure class, applicable sealing
requirements, materials involved, duct4support intervals, and other provisions
in SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible."
E. Longitudinal Seams: Select seam types and fabricate according to
SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible,"
Figure 242, "Rectangular Duct/Longitudinal Seams," for static4pressure class,
applicable sealing requirements, materials involved, duct4support intervals,
BEARDSLEY DESIGN ASSOCIATES
CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 3 OF 14
NOVEMBER 2, 2012
and other provisions in SMACNA's "HVAC Duct Construction Standards 4
Metal and Flexible."
2.3 SINGLE4WALL ROUND[ AND FLAT4OVAL] DUCTS AND FITTINGS
A. General Fabrication Requirements: Comply with SMACNA's "HVAC Duct
Construction Standards 4 Metal and Flexible," Chapter 3, "Round, Oval, and
Flexible Duct," based on indicated static4pressure class unless otherwise
indicated.
1. Manufacturers: Subject to compliance with requirements, available
manufacturers offering products that may be incorporated into the Work
include, but are not limited to, the following:
a. Lindab Inc.
b. McGill AirFlow LLC.
c. SEMCO Incorporated.
d. Sheet Metal Connectors, Inc.
e. Spiral Manufacturing Co., Inc.
B. Flat4Oval Ducts: Indicated dimensions are the duct width (major dimension)
and diameter of the round sides connecting the flat portions of the duct (minor
dimension).
C. Transverse Joints: Select joint types and fabricate according to SMACNA's
"HVAC Duct Construction Standards 4 Metal and Flexible," Figure 341,
"Round Duct Transverse Joints," for static4pressure class, applicable sealing
requirements, materials involved, duct4support intervals, and other provisions
in SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible."
D. Longitudinal Seams: Select seam types and fabricate according to
SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible,"
Figure 342, "Round Duct Longitudinal Seams," for static4pressure class,
applicable sealing requirements, materials involved, duct4support intervals,
and other provisions in SMACNA's "HVAC Duct Construction Standards 4
Metal and Flexible."
E. Tees and Laterals: Select types and fabricate according to SMACNA's
"HVAC Duct Construction Standards 4 Metal and Flexible," Figure 345, "90
Degree Tees and Laterals," and Figure 346, "Conical Tees," for static4
pressure class, applicable sealing requirements, materials involved, duct4
support intervals, and other provisions in SMACNA's "HVAC Duct
Construction Standards 4 Metal and Flexible."
2.4 SHEET METAL MATERIALS
A. General Material Requirements: Comply with SMACNA's "HVAC Duct
Construction Standards 4 Metal and Flexible" for acceptable materials,
material thicknesses, and duct construction methods unless otherwise
indicated. Sheet metal materials shall be free of pitting, seam marks, roller
marks, stains, discolorations, and other imperfections.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 4 OF 14
NOVEMBER 2, 2012
B. Galvanized Sheet Steel: Comply with ASTM A 653/A 653M.
1. Galvanized Coating Designation: G60.
2. Finishes for Surfaces Exposed to View: Mill phosphatized.
C. Tie Rods: Galvanized steel, 1/44inch (64mm) minimum diameter for lengths
36 inches (900 mm) or less; 3/84inch (104mm) minimum diameter for lengths
longer than 36 inches (900 mm).
2.5 DUCT LINER
A. Fibrous4Glass Duct Liner: Comply with ASTM C 1071, NFPA 90A, or
NFPA 90B; and with NAIMA AH124, "Fibrous Glass Duct Liner Standard."
1. Manufacturers: Subject to compliance with requirements, available
manufacturers offering products that may be incorporated into the Work
include, but are not limited to, the following:
a. CertainTeed Corporation; Insulation Group.
b. Johns Manville.
c. Knauf Insulation.
d. Owens Corning.
e. Maximum Thermal Conductivity:
1) Type I, Flexible: 0.27 Btu x in./h x sq. ft. x deg F (0.039 W/m x K)
at 75 deg F (24 deg C) mean temperature.
2) Type II, Rigid: 0.23 Btu x in./h x sq. ft. x deg F (0.033 W/m x K) at
75 deg F (24 deg C) mean temperature.
2. Antimicrobial Erosion4Resistant Coating: Apply to the surface of the liner
that will form the interior surface of the duct to act as a moisture repellent
and erosion4resistant coating. Antimicrobial compound shall be tested for
efficacy by an NRTL and registered by the EPA for use in HVAC systems.
3. Water4Based Liner Adhesive: Comply with NFPA 90A or NFPA 90B and
with ASTM C 916.
a. For indoor applications, use adhesive that has a VOC content of 80
g/L or less when calculated according to 40 CFR 59, Subpart D (EPA
Method 24).
b. Adhesive shall comply with the testing and product requirements of
the California Department of Health Services' "Standard Practice for
the Testing of Volatile Organic Emissions from Various Sources Using
Small4Scale Environmental Chambers."
B. Shop Application of Duct Liner: Comply with SMACNA's "HVAC Duct
Construction Standards 4 Metal and Flexible," Figure 7411, "Flexible Duct
Liner Installation."
1. Adhere a single layer of indicated thickness of duct liner with at least 90
percent adhesive coverage at liner contact surface area. Attaining
indicated thickness with multiple layers of duct liner is prohibited.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 5 OF 14
NOVEMBER 2, 2012
2. Apply adhesive to transverse edges of liner facing upstream that do not
receive metal nosing.
3. Butt transverse joints without gaps, and coat joint with adhesive.
4. Fold and compress liner in corners of rectangular ducts or cut and fit to
ensure butted4edge overlapping.
5. Do not apply liner in rectangular ducts with longitudinal joints, except at
corners of ducts, unless duct size and dimensions of standard liner make
longitudinal joints necessary.
6. Secure liner with mechanical fasteners 4 inches (100 mm) from corners
and at intervals not exceeding 12 inches (300 mm) transversely; at 3
inches (75 mm) from transverse joints and at intervals not exceeding 18
inches (450 mm) longitudinally.
2.6 SEALANT AND GASKETS
A. General Sealant and Gasket Requirements: Surface4burning characteristics
for sealants and gaskets shall be a maximum flame4spread index of 25 and a
maximum smoke4developed index of 50 when tested according to UL 723;
certified by an NRTL.
B. Water4Based Joint and Seam Sealant:
1. Application Method: Brush on.
2. Solids Content: Minimum 65 percent.
3. Shore A Hardness: Minimum 20.
4. Water resistant.
5. Mold and mildew resistant.
6. VOC: Maximum 75 g/L (less water).
7. Maximum Static4Pressure Class: 104inch wg (2500 Pa), positive and
negative.
8. Service: Indoor or outdoor.
9. Substrate: Compatible with galvanized sheet steel (both PVC coated and
bare), stainless steel, or aluminum sheets.
C. Flange Gaskets: Butyl rubber, neoprene, or EPDM polymer with
polyisobutylene plasticizer.
D. Round Duct Joint O4Ring Seals:
1. Seal shall provide maximum leakage class of 3 cfm/100 sq. ft. at 14inch
wg (0.14 L/s per sq. m at 250 Pa) and shall be rated for 104inch wg (25004
Pa) static4pressure class, positive or negative.
2. EPDM O4ring to seal in concave bead in coupling or fitting spigot.
3. Double4lipped, EPDM O4ring seal, mechanically fastened to factory4
fabricated couplings and fitting spigots.
2.7 HANGERS AND SUPPORTS
A. Hanger Rods for Noncorrosive Environments: Cadmium4plated steel rods
and nuts.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 6 OF 14
NOVEMBER 2, 2012
B. Strap and Rod Sizes: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Table 541 (Table 541M), "Rectangular Duct
Hangers Minimum Size," and Table 542, "Minimum Hanger Sizes for Round
Duct."
C. Steel Cables for Galvanized4Steel Ducts: Galvanized steel complying with
ASTM A 603.
D. Steel Cable End Connections: Cadmium4plated steel assemblies with
brackets, swivel, and bolts designed for duct hanger service; with an
automatic4locking and clamping device.
E. Duct Attachments: Sheet metal screws, blind rivets, or self4tapping metal
screws; compatible with duct materials.
F. Trapeze and Riser Supports:
1. Supports for Galvanized4Steel Ducts: Galvanized4steel shapes and
plates.
2.8 MANUAL VOLUME DAMPERS
A. Standard, Steel, Manual Volume Dampers:
1. Suitable for horizontal or vertical applications.
2. Frames:
a. Hat4shaped, galvanized4steel channels, 0.0644inch (1.624mm)
minimum thickness.
b. Mitered and welded corners.
c. Flanges for attaching to walls and flangeless frames for installing in
ducts.
3. Blades:
a. Multiple or single blade.
b. Parallel4 or opposed4blade design.
c. Stiffen damper blades for stability.
d. Galvanized4steel, 0.064 inch (1.62 mm) thick.
4. Blade Axles: Galvanized steel.
5. Bearings:
a. Molded synthetic.
b. Dampers in ducts with pressure classes of 34inch wg (750 Pa) or less
shall have axles full length of damper blades and bearings at both
ends of operating shaft.
B. Damper Hardware:
1. Zinc4plated, die4cast core with dial and handle made of 3/324inch4 (2.44
mm4) thick zinc4plated steel, and a 3/44inch (194mm) hexagon locking nut.
2. Include center hole to suit damper operating4rod size.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 7 OF 14
NOVEMBER 2, 2012
3. Include elevated platform for insulated duct mounting.
2.9 TURNING VANES
A. Manufactured Turning Vanes for Metal Ducts: Curved blades of galvanized
sheet steel; support with bars perpendicular to blades set; set into vane
runners suitable for duct mounting.
1. Acoustic Turning Vanes: Fabricate airfoil4shaped aluminum extrusions
with perforated faces and fibrous4glass fill.
B. General Requirements: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible"; Figures 443, "Vanes and Vane Runners,"
and 444, "Vane Support in Elbows."
C. Vane Construction: Single wall for ducts up to 48 inches (1200 mm) wide
and double wall for larger dimensions.
2.10 DUCT4MOUNTED ACCESS DOORS
A. Duct4Mounted Access Doors: Fabricate access panels according to
SMACNA's "HVAC Duct Construction Standards 4 Metal and Flexible";
Figures 742 (742M), "Duct Access Doors and Panels," and 743, "Access Doors
4 Round Duct."
1. Door:
a. Double wall, rectangular.
b. Galvanized sheet metal with insulation fill and thickness as indicated
for duct pressure class.
c. Hinges and Latches: 14by414inch (254by4254mm) butt or piano hinge
and cam latches.
d. Fabricate doors airtight and suitable for duct pressure class.
2. Frame: Galvanized sheet steel, with bend4over tabs and foam gaskets.
3. Number of Hinges and Locks:
a. Access Doors Less Than 12 Inches (300 mm) Square: No hinges and
two sash locks.
b. Access Doors up to 18 Inches (460 mm) Square: Two hinges and two
sash locks.
c. Access Doors up to 24 by 48 Inches (600 by 1200 mm): Three hinges
and two compression latches with outside and inside handles.
d. Access Doors Larger Than 24 by 48 Inches (600 by 1200 mm): Four
hinges and two compression latches with outside and inside handles.
2.11 FLEXIBLE CONNECTORS
A. Materials: Flame4retardant or noncombustible fabrics.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 8 OF 14
NOVEMBER 2, 2012
B. Coatings and Adhesives: Comply with UL 181, Class 1.
C. Metal4Edged Connectors: Factory fabricated with a fabric strip 341/2 inches
(89 mm) wide attached to 2 strips of 243/44inch4 (704mm4) wide, 0.0284inch4
(0.74mm4) thick, galvanized sheet steel or 0.0324inch4 (0.84mm4) thick
aluminum sheets. Provide metal compatible with connected ducts.
D. Indoor System, Flexible Connector Fabric: Glass fabric double coated with
neoprene.
1. Minimum Weight: 26 oz./sq. yd. (880 g/sq. m).
2. Tensile Strength: 480 lbf/inch (84 N/mm) in the warp and 360 lbf/inch
(63 N/mm) in the filling.
3. Service Temperature: Minus 40 to plus 200 deg F (Minus 40 to plus 93
deg C).
E. Outdoor System, Flexible Connector Fabric: Glass fabric double coated with
weatherproof, synthetic rubber resistant to UV rays and ozone.
1. Minimum Weight: 24 oz./sq. yd. (810 g/sq. m).
2. Tensile Strength: 530 lbf/inch (93 N/mm) in the warp and 440 lbf/inch
(77 N/mm) in the filling.
3. Service Temperature: Minus 50 to plus 250 deg F (Minus 45 to plus 121
deg C).
PART 3 EXECUTION
3.1 DUCT INSTALLATION
A. Drawing plans, schematics, and diagrams indicate general location and
arrangement of duct system. Indicated duct locations, configurations, and
arrangements were used to size ducts and calculate friction loss for air4
handling equipment sizing and for other design considerations. Install duct
systems as indicated unless deviations to layout are approved on Shop
Drawings and Coordination Drawings.
B. Install ducts according to SMACNA's "HVAC Duct Construction Standards 4
Metal and Flexible" unless otherwise indicated.
C. Install round [ and flatoval ] ducts in maximum practical lengths.
D. Install ducts with fewest possible joints.
E. Install factory4 or shop4fabricated fittings for changes in direction, size, and
shape and for branch connections.
F. Unless otherwise indicated, install ducts vertically and horizontally, and
parallel and perpendicular to building lines.
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 9 OF 14
NOVEMBER 2, 2012
G. Install ducts close to walls, overhead construction, columns, and other
structural and permanent enclosure elements of building.
H. Install ducts with a clearance of 1 inch (25 mm), plus allowance for insulation
thickness.
I. Route ducts to avoid passing through transformer vaults and electrical
equipment rooms and enclosures.
J. Where ducts pass through non4fire4rated interior partitions and exterior walls
and are exposed to view, cover the opening between the partition and duct or
duct insulation with sheet metal flanges of same metal thickness as the duct.
Overlap openings on four sides by at least 141/2 inches (38 mm).
K. Where ducts pass through fire4rated interior partitions and exterior walls,
install fire dampers.
L. Protect duct interiors from moisture, construction debris and dust, and other
foreign materials.[ Comply with SMACNA's "IAQ Guidelines for Occupied
Buildings Under Construction," Appendix G, "Duct Cleanliness for New
Construction Guidelines."]
3.2 INSTALLATION OF EXPOSED DUCTWORK
A. Protect ducts exposed in finished spaces from being dented, scratched, or
damaged.
B. Trim duct sealants flush with metal. Create a smooth and uniform exposed
bead. Do not use two4part tape sealing system.
C. Grind welds to provide smooth surface free of burrs, sharp edges, and weld
splatter. When welding stainless steel with a No. 3 or 4 finish, grind the
welds flush, polish the exposed welds, and treat the welds to remove
discoloration caused by welding.
D. Maintain consistency, symmetry, and uniformity in the arrangement and
fabrication of fittings, hangers and supports, duct accessories, and air outlets.
E. Repair or replace damaged sections and finished work that does not comply
with these requirements.
3.3 DUCT SEALING
A. Seal ducts for leakage classes in table below:
DUCT TYPE LEAKAGE CLASS, CFM/100 ft at 1” wg
Metal (flexible excluded)
Round and Flat Oval [3]
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CORNELL – NCP METAL DUCTS
STANDARD SPECIFICATIONS 23 31 13 – PAGE 10 OF 14
NOVEMBER 2, 2012
Rectangular [6]
Flexible [6]
B. Note: Leakage classes for specific applications may be specified elsewhere
in this specification.
MINIMUM DUCT SEAL LEVELA
DUCT TYPE
Duct Location Supply
<2 in. w.c.b >2 in. w.c.b. Exhaust Return
Outdoor A A C A
Unconditioned
Spaces
B A C B
Conditioned
Spacesc
C B B C
a See description of seal levels below.
b Duct design static pressure classification.
c Includes indirectly conditioned spaces such as return air plenums.
C. Longitudinal seams are joints oriented in the direction of airflow. Transverse
joints are connections of two duct sections oriented perpendicular to airflow.
Duct wall penetrations are openings made by any screw fastener, pipe, rod,
or wire. Spiral lock seams in a round or flat oval duct need not be sealed. All
other connections are considered transverse joints, including but not limited
to spin4ins, taps, and other branch connections, access door frames and
jambs, duct connections to equipment, etc.
3.4 HANGER AND SUPPORT INSTALLATION
A. Comply with SMACNA's "HVAC Duct Construction Standards 4 Metal and
Flexible," Chapter 5, "Hangers and Supports."
B. Building Attachments: Concrete inserts, powder4actuated fasteners, or
structural4steel fasteners appropriate for construction materials to which
hangers are being attached.
1. Where practical, install concrete inserts before placing concrete.
2. Install powder4actuated concrete fasteners after concrete is placed and
completely cured.
3. Use powder4actuated concrete fasteners for standard4weight aggregate
concretes or for slabs more than 4 inches (100 mm) thick.
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STANDARD SPECIFICATIONS 23 31 13 – PAGE 11 OF 14
NOVEMBER 2, 2012
4. Do not use powder4actuated concrete fasteners for lightweight4aggregate
concretes or for slabs less than 4 inches (100 mm) thick.
5. Do not use powder4actuated concrete fasteners for seismic restraints.
C. Hanger Spacing: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Table 541 (Table 541M), "Rectangular Duct
Hangers Minimum Size," and Table 542, "Minimum Hanger Sizes for Round
Duct," for maximum hanger spacing; install hangers and supports within 24
inches (610 mm) of each elbow and within 48 inches (1200 mm) of each
branch intersection.
D. Hangers Exposed to View: Threaded rod and angle or channel supports.
E. Support vertical ducts with steel angles or channel secured to the sides of the
duct with welds, bolts, sheet metal screws, or blind rivets; support at each
floor and at a maximum intervals of 16 feet (5 m).
F. Install upper attachments to structures. Select and size upper attachments
with pull4out, tension, and shear capacities appropriate for supported loads
and building materials where used.
3.5 CONNECTIONS
A. Make connections to equipment with flexible connectors.
B. Comply with SMACNA's "HVAC Duct Construction Standards 4 Metal and
Flexible" for branch, outlet and inlet, and terminal unit connections.
3.6 PAINTING
A. Paint interior of metal ducts that are visible through registers and grilles and
that do not have duct liner. Apply one coat of flat, black, latex paint over a
compatible galvanized4steel primer.
3.7 FIELD QUALITY CONTROL
A. Perform tests and inspections.
B. Leakage Tests:
1. Comply with SMACNA's "HVAC Air Duct Leakage Test Manual." Submit a
test report for each test.
2. Test the following systems:
a. Supply Ducts with a Pressure Class of 24Inch wg (500 Pa) or Higher:
Test representative duct sections totaling no less than 50 percent of
total installed duct area for each designated pressure class.
b. Return Ducts with a Pressure Class of 24Inch wg (500 Pa) or Higher:
Test representative duct sections totaling no less than 50 percent of
total installed duct area for each designated pressure class.
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STANDARD SPECIFICATIONS 23 31 13 – PAGE 12 OF 14
NOVEMBER 2, 2012
c. Exhaust Ducts with a Pressure Class of 24Inch wg (500 Pa) or Higher:
Test representative duct sections totaling no less than 50 percent of
total installed duct area for each designated pressure class.
3. Disassemble, reassemble, and seal segments of systems to
accommodate leakage testing and for compliance with test requirements.
4. Test for leaks before applying external insulation.
5. Conduct tests at static pressures equal to maximum design pressure of
system or section being tested. If static4pressure classes are not
indicated, test system at maximum system design pressure. Do not
pressurize systems above maximum design operating pressure.
6. Give seven days' advance notice for testing.
C. Duct system will be considered defective if it does not pass tests and
inspections.
D. Prepare test and inspection reports.
3.8 DUCT CLEANING
A. Clean new and existing duct system(s) before testing, adjusting, and
balancing.
B. Use service openings for entry and inspection.
1. Create new openings and install access panels appropriate for duct static4
pressure class if required for cleaning access. Provide insulated panels
for insulated or lined duct. Patch insulation and liner as recommended by
duct liner manufacturer.
2. Disconnect and reconnect flexible ducts as needed for cleaning and
inspection.
3. Remove and reinstall ceiling to gain access during the cleaning process.
C. Clean the following components by removing surface contaminants and
deposits:
1. Air outlets and inlets (registers, grilles, and diffusers).
2. Supply, return, and exhaust fans including fan housings, plenums (except
ceiling supply and return plenums), scrolls, blades or vanes, shafts,
baffles, dampers, and drive assemblies.
3. Coils and related components.
4. Return4air ducts, dampers, actuators, and turning vanes except in ceiling
plenums and mechanical equipment rooms.
5. Supply4air ducts, dampers, actuators, and turning vanes.
6. Dedicated exhaust and ventilation components and makeup air systems.
3.9 START UP
A. Air Balance: Comply with requirements in Division 23 Section "Testing,
Adjusting, and Balancing for HVAC."
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STANDARD SPECIFICATIONS 23 31 13 – PAGE 13 OF 14
NOVEMBER 2, 2012
3.10 DUCT SCHEDULE
A. Supply Duct Pressure Class:
1. Pressure Class: Positive 24inch wg (500 Pa).
B. Return Duct Pressure Class:
1. Pressure Class: Positive or negative 24inch wg (500 Pa).
C. Exhaust Duct Pressure Class:
1. Ducts Connected to Fans Exhausting (ASHRAE 62.1, Class 1 and 2) Air:
a. Pressure Class: Negative 24inch wg (500 Pa).
D. Elbow Configuration:
1. Rectangular Duct: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Figure 442, "Rectangular Elbows."
a. Velocity 1000 fpm (5 m/s) or Lower:
1) Radius Type RE 1 with minimum 0.5 radius4to4diameter ratio.
2) Mitered Type RE 4 without vanes.
b. Velocity 1000 to 1500 fpm (5 to 7.6 m/s):
1) Radius Type RE 1 with minimum 1.0 radius4to4diameter ratio.
2) Radius Type RE 3 with minimum 0.5 radius4to4diameter ratio and
two vanes.
3) Mitered Type RE 2 with vanes complying with SMACNA's "HVAC
Duct Construction Standards 4 Metal and Flexible," Figure 443,
"Vanes and Vane Runners," and Figure 444, "Vane Support in
Elbows."
c. Velocity 1500 fpm (7.6 m/s) or Higher:
1) Radius Type RE 1 with minimum 1.5 radius4to4diameter ratio.
2) Radius Type RE 3 with minimum 1.0 radius4to4diameter ratio and
two vanes.
3) Mitered Type RE 2 with vanes complying with SMACNA's "HVAC
Duct Construction Standards 4 Metal and Flexible," Figure 443,
"Vanes and Vane Runners," and Figure 444, "Vane Support in
Elbows."
2. Round Duct: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Figure 344, "Round Duct Elbows."
a. Minimum Radius4to4Diameter Ratio and Elbow Segments: Comply
with SMACNA's "HVAC Duct Construction Standards 4 Metal and
Flexible," Table 341, "Mitered Elbows." Elbows with less than 904
degree change of direction have proportionately fewer segments.
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STANDARD SPECIFICATIONS 23 31 13 – PAGE 14 OF 14
NOVEMBER 2, 2012
1) Velocity 1000 fpm (5 m/s) or Lower: 0.5 radius4to4diameter ratio
and three segments for 904degree elbow.
2) Velocity 1000 to 1500 fpm (5 to 7.6 m/s): 1.0 radius4to4diameter
ratio and four segments for 904degree elbow.
3) Velocity 1500 fpm (7.6 m/s) or Higher: 1.5 radius4to4diameter ratio
and five segments for 904degree elbow.
4) Radius4to Diameter Ratio: 1.5.
b. Round Elbows, 12 Inches (305 mm) and Smaller in Diameter:
Stamped or pleated.
c. Round Elbows, 14 Inches (356 mm) and Larger in Diameter: Standing
seam.
E. Branch Configuration:
1. Rectangular Duct: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Figure 446, "Branch Connection."
a. Rectangular Main to Rectangular Branch: 454degree entry.
b. Rectangular Main to Round Branch: Spin in.
2. Round and Flat Oval: Comply with SMACNA's "HVAC Duct Construction
Standards 4 Metal and Flexible," Figure 345, "90 Degree Tees and
Laterals," and Figure 346, "Conical Tees." Saddle taps are permitted in
existing duct.
a. Velocity 1000 fpm (5 m/s) or Lower: 904degree tap.
b. Velocity 1000 to 1500 fpm (5 to 7.6 m/s): Conical tap.
c. Velocity 1500 fpm (7.6 m/s) or Higher: 454degree lateral.
END OF SECTION 23 31 13