**CONSTRUCTION STANDARD SPECIFICATION**

**SECTION 15810**

**[DUCTWORK]{.underline}**

Page

PART 1 - GENERAL

[[1.01]{.smallcaps} [Summary]{.smallcaps} 2](#summary)

[[1.02]{.smallcaps} [References]{.smallcaps} 2](#references)

[[1.03]{.smallcaps} [Submittals]{.smallcaps} 3](#submittals)

[[1.04]{.smallcaps} [Quality Assurance]{.smallcaps}
4](#quality-assurance)

[[1.05]{.smallcaps} [Warranty]{.smallcaps} 5](#warranty)

PART 2 - PRODUCTS

[[2.01]{.smallcaps} [Materials, General]{.smallcaps}
5](#materials-general)

[[2.02]{.smallcaps} [Design And Construction]{.smallcaps}
7](#design-and-construction)

[[2.03]{.smallcaps} [Dampers]{.smallcaps} 9](#dampers)

[[2.04]{.smallcaps} [Hangers And Supports]{.smallcaps}
11](#hangers-and-supports)

[[2.05]{.smallcaps} [Sealants]{.smallcaps} 12](#sealants)

[[2.06]{.smallcaps} [Access Doors]{.smallcaps} 12](#access-doors)

[[2.07]{.smallcaps} [Louvers]{.smallcaps} 13](#louvers)

PART 3 - EXECUTION

[[3.01]{.smallcaps} [Examination]{.smallcaps} 13](#examination)

[[3.02]{.smallcaps} [Preparation]{.smallcaps} 13](#preparation)

[[3.03]{.smallcaps} [Installation]{.smallcaps} 14](#installation)

[[3.04]{.smallcaps} [Gas Fired Equipment]{.smallcaps}
15](#gas-fired-equipment)

[[3.05]{.smallcaps} [Duct Liners]{.smallcaps} 15](#duct-liners)

[[3.06]{.smallcaps} [Hangers And Supports]{.smallcaps}
15](#hangers-and-supports-1)

[[3.07]{.smallcaps} [Connectors]{.smallcaps} 16](#connectors)

[[3.08]{.smallcaps} [Dampers]{.smallcaps} 16](#dampers-1)

[[3.09]{.smallcaps} [Access Doors]{.smallcaps} 17](#access-doors-1)

[[3.10]{.smallcaps} [Plenums]{.smallcaps} 17](#plenums)

[[3.11]{.smallcaps} [Duct Penetrations]{.smallcaps}
18](#duct-penetrations)

[[3.12]{.smallcaps} [Louvers]{.smallcaps} 18](#louvers-1)

[[3.13]{.smallcaps} [Filters And Gauges]{.smallcaps}
18](#filters-and-gauges)

[[3.14]{.smallcaps} [Inspection And Testing]{.smallcaps}
18](#inspection-and-testing)

[3.15 Cleaning 19](#cleaning)

**CONSTRUCTION STANDARD SPECIFICATION**

**SECTION 15810**

**[DUCTWORK]{.underline}**

# PART 1 - GENERAL

## 1.01 SUMMARY

A.  Section Includes: This specification, in conjunction with the
    contract documents and design drawings, provides the minimum
    requirements for materials and operations used in the fabrication
    and installation of ductwork. Systems covered by this document
    include heating, ventilating, air conditioning and exhaust for
    pressure classes from minus 10 inches to plus 10 inches water gauge.
    Operations include the specification of ductwork materials, gauges,
    pressure classifications, construction, duct liners, filters,
    dampers, connectors, supports, testing and certifications. This
    specification does not include ductwork requirements for materials
    handling systems. The materials, products, accessories, and methods
    listed in this specification shall be followed unless noted
    otherwise on the drawings. All work performed under this
    specification shall conform to Section 15050, \"Basic Mechanical
    Materials and Methods.\"

## 1.02 REFERENCES

A.  The latest edition of the following codes and standards shall be
    used. Where differences between Standards and this specification
    exist, this specification shall take precedence. Where Standards
    allow for the use alternate materials and methods, the contractor
    shall submit for approval a request to use alternate materials and
    methods before beginning work.

```{=html}
<!-- -->
```
B.  Sheet Metal And Air Conditioning Contractors\' National Association
    (SMACNA)

    HVAC Duct Construction Standards - Metal and Flexible

    HVAC Duct Systems Design

    Fire, Smoke and Radiation Damper Installation Guide for HVAC Systems

    Accepted Industry Practice for Industrial Duct Design

    HVAC Systems - Testing, Adjusting and Balancing

    Round Industrial Duct Construction Standards

    Rectangular Industrial Duct Construction Standards

    HVAC Air Duct Leakage Test Manual.

C.  National Fire Protection Association (NFPA)

    80 Standard for Fire Doors and Windows

    90A Standard for Installation of AC and Ventilation Systems

    90B Standard for Installation of Warm Air Heating and AC Systems

    255 Building Materials, Test of Burning Characteristics (same as
    ASTM E84)

D.  American Society for Testing and Materials (ASTM)

    A240 Standard Specification for Heat-Resisting Chromium and
    Chromium-Nickel Stainless Steel Plate, Sheet and Strip for Pressure
    Vessels

    A480 Standard Specification for General Requirements for Flat Rolled
    Stainless Heat-Resisting Steel Plate, Sheet and Strip

    A653 Standard Specification for Steel Sheet, Zinc Coated
    (Galvanized) or Zinc-Iron Alloy-Coated by the Hot Dip Process

    C916

    C1071

    E84 Standard Test Method for Surface Burning Characteristics of
    Building Materials

    E477 Standard Test Method for Measuring Acoustical and Airflow
    Performance of Duct Liner Material and Prefabricated Silencers

    E814 Standard Test Method for Fire Tests of Through Penetration Fire
    Stops

E.  American Welding Society (AWS)

    B2.2 Brazing Procedures and Performance Qualifications

    D9.1 Sheet Metal Welding Code

F.  Underwriter\'s Laboratories (UL)

```{=html}
<!-- -->
```
181. Factory Made Air Ducts and Air Connectors

```{=html}
<!-- -->
```
555. Standard for Safety Fire Dampers

> 555S Leakage Rated Dampers for Use in Smoke Control Systems
>
> 723 Test for Surface Burning Characteristics of Burning Materials
> (ASTM E84)

A.  North American insulation Manufactures Association (NAIMA

    AH124 Fibrous Glass Duct Liner Standard

## 1.03 SUBMITTALS

General: Manufacturers, products and model numbers cited in this
specification are meant to serve as a guide to minimum standards set
forth by this specification. Proposed substitutions that can meet these
minimum standards are allowed for submittal, and shall be included in
the submittal package furnished to the Sandia Delegated Representative
(SDR) for consideration and approval, prior to commencement of work.
Submittals shall conform to Section 01330, "Submittal Procedures.\"

A.  Shop Drawings: Submit shop drawings for the following items:

    1.  Plenums and plenum related items showing physical dimensions,
        joints, sealants, door construction and hardware.

    2.  Factory fabricated ducts, fittings and joining systems.

    3.  Firewall duct penetrations; fire and smoke dampers; louvers and
        access doors.

```{=html}
<!-- -->
```
B.  Submit Material Safety Data Sheets on sealants and adhesives.

C.  Submit changes or alterations in ductwork layout, with supporting
    calculations showing that the modified design will not increase
    total pressure, before work commences. Submittals for proposed
    changes shall be stamped for approval prior to commencement of work.

D.  Submit control-wiring diagrams for automatic dampers and other
    automated ductwork accessories.

E.  Duct Coordination Drawings (Duct Shop Drawings): When required on
    the Descriptive Submittal List, the contractor shall submit ¼ inch
    or 1/8 inch scale plan drawings of duct work layout with overlays of
    other major systems, structures, and equipment that could interfere
    with the routing of the ductwork. Include reflected ceiling layout,
    ceiling and wall mounted access doors and panels required to provide
    access to dampers and other operating devices, and ceiling mounted
    items including light fixtures, diffusers, grills, speakers, and
    sprinklers. Include elevation sections through congested areas. Base
    input on information from installers of items involved and when
    possible field verify obstacles to the duct layout.

F.  Ductwork Reinforcement Information: When required by the Descriptive
    Submittal List or requested by the Sandia Construction Observer
    (SCO), submit information on the duct reinforcement to be used for
    each section of duct. Information shall include copies of tables
    from SMACNA construction standards highlighting the actual duct
    sizes, pressure class, material, gauge, reinforcement type and
    spacing, joint type and spacing, applied loads, and hanger type and
    spacing. When alternated methods of sizing are used as provided by
    SMACNA, provide calculations to support the reinforcement selection.

G.  Alternative Materials and Methods: Proposed deviations of materials
    and methods from these specifications require approved submittal
    information prior to any construction. Submittals should clearly
    note that the submittals is for a change to the specifications and
    identify the applicable paragraph from this specification.
    Submittals shall include physical descriptions and results of
    testing and analysis to support the equal performance of the
    substituted items. Testing and analysis shall follow the guidelines
    for "Functional Criteria from SMACNA standards.

## 1.04 QUALITY ASSURANCE

A.  Employ qualified sheet metal workers in accordance with SMACNA Duct
    Construction Standards.

```{=html}
<!-- -->
```
H.  Asbestos Free: Insulating and sealing materials must be certified to
    be free of asbestos.

I.  Brazing: Certify brazing procedures, brazers, and operators in
    accordance with AWS B2.2 Brazing Procedures and Performance
    Qualifications.

J.  Welding: Certify welding procedures, welding equipment and welders
    in accordance with AWS D9.1 Sheet Metal Welding Code.

K.  Attachments, such as conduit and pipe, to ductwork are not
    permitted.

## 1.05 WARRANTY

A.  Ductwork system components furnished under this contract shall be
    guaranteed against defective design, materials, and workmanship for
    the full warranty period, which is standard with the manufacturer or
    supplier, but in no case less than one year from the date of system
    acceptance.

# PART 2 - PRODUCTS

## 2.01 MATERIALS, GENERAL

A.  Rigid Ducts, Casings and Fittings: Shall be made from galvanized
    steel sheets of lock form quality per ASTM A653 with a G90 zinc
    coating (0.90 oz/ft^2^ both sides), unless otherwise shown on the
    contract documents. Sheets shall be free of pits, blisters, slivers,
    and ungalvanized spots.

```{=html}
<!-- -->
```
L.  PVC Coated Rigid Ducts, Casings and Fittings: Shall be made from
    galvanized steel sheets of lock form quality per ASTM A653 with a
    G60 zinc coating (0.60 oz/ft^2^ both sides), unless otherwise shown
    on the contract documents. Provide with factory applied 4-mil PVC
    coating on exposed surfaces (exterior of duct for underground
    applications and interior of ducts and fittings for fume handling)
    and 2-mil coating on opposing sides of ductwork. Ductwork shall be
    UL-181, Class 1 listed.

M.  Stainless Ductwork: Unless noted otherwise on the drawings,
    stainless steel ductwork shall be Type 316L steel sheet per ASTM
    A480 and ASTM A240 with a finished surfaced No. 4 for exposed
    locations, and No. 2B for concealed locations. When 'Welded Duct' is
    called out on the drawings, ducts shall be have longitudinally
    welded seams and welded or flanged joints and connections to
    equipment or accessories.

N.  Supports: Angle iron, channels, rods and related supporting
    materials shall be galvanized or red oxide coated.

O.  Fasteners: Use galvanized rivets, screws and bolts throughout,
    except on stainless steel ductwork, use SS fasteners.

P.  Reinforcement: Provide galvanized steel or stainless steel
    reinforcement shapes and plates where required.

Q.  Tie Rods: Use galvanized steel, 1/4 inch minimum diameter fasteners
    for ductwork 36 inch or less in length; use 3/8 inch minimum
    diameter for lengths longer than 36 in.

R.  Flexible Duct - Supply & Return Air (Insulated, Low Pressure): Duct
    to be a factory fabricated assembly with a laminated inner liner of
    aluminum foil, fiberglass and polyester, a galvanized steel helix
    coil formed to the inner liner, a fiberglass insulation blanket, and
    a polyethylene outer jacket. Flexible duct shall be rated for 6.0"
    w.g. positive pressure, 4.0" w.g. negative pressure thru 16"
    diameter, 4000 FPM velocity, -20 to 250 deg. F operating
    temperature, 0.1 perm rating, and have a maximum thermal conductance
    of 0.23 BTUH/Hr-Deg F. Flexible duct shall have a flame resistant
    rating of 25 or less and a smoke developed rating of 50 or less.
    Flexible duct shall be tested in accordance with UL 181 and listed
    and labeled as Class 0 or Class 1. Flexmaster Type 5 or equal.

S.  Flexible Duct - Supply & Return Air (Insulated, High Pressure): Duct
    to be a factory fabricated assembly with a laminated inner liner of
    aluminum foil, fiberglass and polyester, a galvanized steel helix
    coil formed to the inner liner, a fiberglass insulation blanket, and
    a polyethylene outer jacket. Flexible duct shall be rated for 12.0"
    w.g. positive pressure, 5.0" w.g. negative pressure thru 16"
    diameter, 5500 FPM velocity, -20 to 250 deg. F operating
    temperature, 0.1 perm rating, and have a maximum thermal conductance
    of 0.23 BTUH/Hr-Deg F. Flexible duct shall have a flame resistant
    rating of 25 or less and a smoke developed rating of 50 or less.
    Flexible duct shall be tested in accordance with UL 181 and listed
    and labeled as Class 0 or Class 1. Flexmaster Type 3 or equal.

T.  Flexible Duct -- Lab Exhaust Systems: Ductwork to be a factory
    fabricated assembly of neoprene-coated polyester with galvanized
    steel helix reinforcement. Flexible duct shall be rated for a
    minimum of 6.0" w.g. positive pressure, 4.0" w.g. negative pressure,
    5500 FPM velocity, -65 to 250 degrees F. Flexible duct shall have a
    flame resistant rating of 25 or less and a smoke developed rating of
    50 or less. Uni-flex Model U-LOK 200 or equal.

U.  Mechanical Liner and Fasteners:

    1.  Liners: Internal duct liners shall be 1 inch thick fiberglass
        Type I or II per ASTM 1071 and have a thermal conductivity
        (k-value) of 0.26 at 75 deg. F. Liners shall comply with NFPA
        90A and 90B and with NAIMA AH124 and have a maximum flame-spread
        index of 25 and smoke-developed index of 50 when tested
        according to ASTM E84. Liners shall be treated with an EPA
        approved biocide to resist bacterial and fungal growth. All
        surfaces exposed to the air stream shall be coated to prevent
        erosion of glass fibers.

    2.  Mechanical Fasteners: galvanized steel, suitable for adhesive,
        mechanical or welding attachment (self-stick adhesive fasteners
        are not permitted). Provide fasteners that will not damage the
        liner when applied as recommended by the manufacturer, that do
        not cause leakage within the duct and that will sustain a
        50-pound tensile dead load perpendicular to duct wall.

    3.  Liner Adhesive: Non-oxidizing, vinyl acrylic, water-based
        adhesive used to bond insulation to sheet metal surfaces.
        Operational temperature range -20 to +160°F; curing time 24
        hours. Manufactured by United McGill, type Uni-Tack. Comply with
        NFPA 90A and 90B and with ASTM C916

## 2.02 DESIGN AND CONSTRUCTION

A.  General:

    1.  Construct all ducts, casings and fittings of rigid, galvanized
        steel, unless otherwise shown in the contract documents.

    2.  Contractor is responsible for coordination between the ductwork
        trade and the other mechanical, electrical and architectural
        trades.

    3.  Insulation shall be as specified in Section 15081, \"Duct
        Insulation.\"

    4.  Install internal duct liners on ducts indicated to have liners
        on the construction drawings. Install liners per NAIMA duct
        liner guidelines.

```{=html}
<!-- -->
```
V.  Ductwork Pressure Classification

    Unless otherwise indicated on the construction drawings, ductwork
    shall be constructed to meet the appropriate pressure class defined
    below.

    1.  Ductwork from the supply air fan to the terminal velocity
        reduction device (VAV box) or zone-tempering coil shall be
        fabricated to meet minimum 4\" w.g. internal pressure.

    2.  Ductwork from downstream of terminal velocity reduction device
        (VAV box) or zone tempering coil shall be fabricated to meet
        minimum 1\" w.g. internal pressure.

    3.  Return air ductwork shall be fabricated to meet minimum 1\" w.g.
        internal pressure.

    4.  Lab exhaust ductwork shall be fabricated to meet the lower of
        either 4\" w.g. negative pressure, or the exhaust fan pressure
        at shut-off.

    5.  Restroom exhaust and general exhaust ductwork shall be
        fabricated to meet the lower of either 2\" w.g. negative
        pressure, or the exhaust fan pressure at shut-off.

    6.  Acid resistant ductwork (PVC coated) shall be fabricated to meet
        3\" w.g. on supply ducts and negative 2\" w.g. on return and
        exhaust ducts.

W.  Plenums:

    1.  Main air handling (equipment) plenum walls, doors, and roof
        shall be factory built as follows: 18 gauge galvanized steel,
        minimum, double-wall construction (perforated inner walls) 4
        inch acoustical insulated casing (top and sides) to provide a
        \"U\"-value of 0.06 Btu/hr-ft²-°F, hinged access doors with 90°
        latching handles to all compartments (double-wall insulated
        doors with air-tight sealing gaskets). Doors shall be provided
        with 12"x12" double pane, hermetically sealed observation
        windows of wire-reinforced glass. Panels shall be provided with
        (end, bottom or top) supply and return duct openings, as shown
        on the drawings; return air and outside air dampers shall be
        furnished where indicated. Interior partition walls shall be
        perforated 20 gauge steel acoustic panels sandwiching 4\"
        minimum thickness, 1.5 lb/cu.ft. rigid fiberglass insulation,
        reinforced to be rigid under all operating conditions.

    2.  All other plenums shall be factory or site built of 16 gauge
        galvanized metal panels. Maximum width of panel shall be 21\".
        One end of panel shall be flanged 1\" and opposite end formed
        with 1\" double standing seam.

X.  Rectangular Ductwork: Shall conform to SMACNA HVAC Duct Construction
    Standards, Metal and Flexible or SMACNA Rectangular Industrial Duct
    Construction Standards, except:

    1.  Addendum No. 1 (November 1997) covering Midpanel Tie Rod use
        shall not be used.

    2.  Construct ducts using Pittsburgh Lock or Double Corner seams
        except Snap Lock seams may be used for pressure classes of 2
        inch or less.

    3.  Cross-Breaking:

        a.  Sheet metal ducts and fittings over 18 inches shall be
            cross-broken; or otherwise stiffened to eliminate oil
            canning or vibration.

        b.  Vertical and horizontal sheet metal barriers, duct offsets,
            and elbows shall be cross-broken.

        c.  Cross-breaking shall be applied to the sheet metal between
            the standing seams or reinforcing angles; the center of
            cross-break shall be of the required height to assure
            surfaces being rigid.

    4.  Radius Elbows: Radius elbows with a rectangular cross section
        shall have a centerline radius of not less than the width of the
        duct or shall be furnished with single thickness splitter vanes.
        A single splitter vane shall be used for elbows with a ratio of
        inside radius to duct width of 0.5 to 0.2. Two splitter vanes
        shall be used for ratios less that 0.20.

    5.  Square Elbows: Square elbows shall be equipped with either
        single or double thickness turning vanes with a radius of 4.5",
        and a separation of 3.25", pre-assembled on runners constructed
        per SMACNA Accepted Industry Practice for Industrial Duct
        Design. Vanes shall be securely attached to the runners. Vanes
        shall be welded to the runners in systems with pressures greater
        than 6" w.g. or velocities greater than 3000 FPM. The maximum
        unsupported length of vanes shall be 36".

Y.  Round Ductwork:

    1.  Spiral lockseam or longitudinal welded seam as manufactured by
        United McGill Sheet Metal Company. Models Uniseal, Unicoat, or
        Longitudinal Seam.

    2.  Minimum galvanized steel or stainless steel gauges, hanger
        spacing, and reinforcement shall be per SMACNA HVAC Duct
        Construction Standards - Metal and Flexible for pressures from
        negative 4" w.g. up to positive 10" w.g. For pressures less than
        negative 4" w.g., or greater than positive 10" w.g., minimum
        galvanized steel or stainless steel gauges, hanger spacing, and
        reinforcement shall be per SMACNA Round Industrial Duct
        Construction Standards.

    3.  Fittings: Fittings shall have a wall thickness not less than
        that required for longitudinal-seam straight duct.

    4.  Elbows:

        a.  Elbows for round ducts shall have a minimum centerline
            radius of 1-1/2 times the diameter of the duct and shall be
            constructed without splitters.

        b.  Smooth or stamped elbows shall be used whenever possible.

        c.  When gored elbows are used they shall be constructed as
            follows: Elbows up to 36° shall have 2 gores, 37° through
            72° shall have 3 gores, and 73° through 90° shall have 5
            gores.

        d.  Four gore adjustable elbows are permitted for systems rated
            at 1 in. w.g. or less. The gores shall be tack welded or
            coated with sealer on diameters from 8" to 14". Diameters
            above 14" shall be tack welded.

Z.  Flat Oval Ductwork: Ductwork and fitting spiral lockseam or welded
    with gauges, reinforcement, and supports conforming to SMACNA Duct
    Construction Standards Metal and Flexible: Positive pressure
    applications only, up to 10\" w.g. For negative pressure
    applications, submit special design and reinforcements required.

## 2.03 DAMPERS

A.  Fire Dampers:

    1.  Fire Dampers shall be installed at locations shown on the
        drawings and shall meet the requirements of NFPA 90A. Dampers
        shall be constructed, tested and stamped in accordance with
        UL555 consistent with the fire rating of the partition in which
        they are installed.

    2.  Dampers shall be classified for "Dynamic Closure" to shutoff
        against airflow for a minimum of 2375 FPM and 4" w.g. for
        horizontal or vertical flow. Each damper shall bear a UL stamp
        be marked with the UL hour classification, flow direction, and
        maximum pressure and velocity and "for use in dynamic systems".

    3.  The dampers shall be curtain type and the fire damper\'s blades
        shall be retained in a recess such that the free area of
        connecting ductwork is not reduced.

    4.  Fire dampers shall be rated for a minimum of 1 1/2 hours and
        have a fusible link rated 50 °F above the maximum temperature of
        the system, but not less than 160 °F.

    5.  Provide a hook on the fusible link, so that link can be easily
        removed to check damper for operation.

    6.  Each damper shall be shipped with the manufactures UL
        installation instructions and the dampers shall be installed in
        accordance with these instructions.

```{=html}
<!-- -->
```
A.  Combination Fire/Smoke Dampers:

    1.  Combination Fire/Smoke Dampers shall be installed at locations
        shown on the drawings and shall meet the requirements of NFPA
        90A. Dampers shall be constructed, tested and stamped in
        accordance with UL555 and UL555S consistent with the fire rating
        of the partition in which they are installed.

    2.  Dampers shall be classified for "Dynamic Closure" to shutoff
        against airflow for a minimum of 2375 FPM and 4" w.g. for
        horizontal or vertical flow. Each damper shall bear a UL stamp
        be marked with the UL hour classification, flow direction, and
        maximum pressure and velocity and "for use in dynamic systems".

    3.  Dampers shall be supplied with a factory-mounted actuator.
        Single piece airfoil damper blades for rectangular dampers.
        Leakage Class I and temperature rated to withstand temperatures
        to 450^o^F.

    4.  Fire dampers shall be rated for a minimum of 1 1/2 hours and
        have a fusible link rated 50 °F above the maximum temperature of
        the system, but not less than 160 °F.

    5.  Provide a hook on the fusible link, so that link can be easily
        removed to check damper for operation.

    6.  Each damper shall be shipped with the manufactures UL
        installation instructions and the dampers shall be installed in
        accordance with these instructions.

B.  Outside Air Dampers: Dampers shall be low-leakage, airfoil, type;
    6063 T5 heavy gage aluminum blades and frame; extruded vinyl seals.
    Manufactured by Ruskin; model CD-50.

C.  Manual Balancing Dampers (Supply Air and General Exhaust Systems):

    Dampers may be factory or contractor fabricated per SMACNA Duct
    Construction Standards Metal and Flexible section for Volume Dampers
    with the following exceptions:

    1.  Dampers shall be prefabricated in a frame to attach to the duct.
        The frame for rectangular dampers shall be minimum 16 gauge
        galvanized steel structural hat channel with reinforced corners.

    2.  Bearings shall be sleeve type synthetic or oil impregnated
        bronze, pressed into the frame.

    3.  Dampers shall have an external locking manual quadrant. On duct
        systems with external insulation, the quadrant shall be
        installed with a standoff bracket to clear the insulation. The
        quadrant shall have a wing nut for locking the damper in place
        and a scale for indicating the position of the damper. (A handle
        attached directly to the damper shaft is not acceptable)

    4.  The end of the shaft shall be permanently marked to indicate
        blade position.

    5.  Dampers shall be of the same material as the duct material.

    6.  Blades shall be positively locked to the shafts.

    7.  Round dampers up to 24" shall be single blade butterfly type.
        Frames shall include rolled stiffener beads to allow easy
        sealing of spiral ductwork joints.

D.  Manual Balancing Dampers (Lab Exhaust Systems):

    Dampers shall be factory fabricated either butterfly or blast gate
    type and rated for up to 3000 FPM velocity and 4" w.g. For pressures
    greater than negative 4" w.g., dampers shall be constructed per
    SMACNA Round Industrial Duct Construction Standards.

    1.  Bearings shall be sleeve type synthetic or oil impregnated
        bronze, pressed into the frame.

    2.  All butterfly dampers shall have an external locking manual
        quadrant. On duct systems with external insulation, the quadrant
        shall be installed with a standoff bracket to clear the
        insulation. The quadrant shall have a wing nut for locking the
        damper in place and a scale for indicating the position of the
        damper. (A handle attached directly to the damper shaft is not
        acceptable)

    3.  Blast gate dampers shall have a bolt to lock the blade in
        position.

    4.  The end of the shaft shall be permanently marked to indicate
        blade position.

    5.  Dampers shall be of the same material as the duct material.

    6.  Continuous through shafts of ½" diameter and welded or bolted to
        the blades.

E.  Control Dampers: Control dampers shall be furnished under section
    13493 -- HVAC Controls and Energy Management System and as listed on
    the drawings.

## 2.04 HANGERS AND SUPPORTS

A.  General: Refer to SMACNA Duct Construction Standards - Metal and
    Flexible, Rectangular Industrial Duct Construction Standards, and
    Round Industrial Duct Construction Standards respectively for
    rectangular and round ductwork for installation of hangers and
    spacing.

    1.  Straps and angles shall be manufactured from galvanized steel;
        rods shall be manufactured from uncoated or galvanized steel.

    2.  Perforated iron band for duct support is prohibited.

    3.  Wire for duct support is prohibited.

```{=html}
<!-- -->
```
F.  Building Attachments: Shall be concrete inserts, powder actuated
    fasteners or structural steel fasteners compatible with building
    materials. Do not use powder-actuated fasteners for concrete slabs
    less than 4 inches thick. Screwed fasteners shall be load rated.

G.  Exterior Ducts: Unless detailed otherwise on the drawings, exterior
    ducts supported on roofs shall be supported with structural steel
    angle or channel sized per SMACNA standards for trapeze hangers and
    supported with pipe or angle columns.

    1.  Hangers shall be spaced a minimum of 5' on center.

    2.  The minimum size of the trapeze hanger shall be 1-1/2" x 1-1/2"x
        3/16" angle or 3 X 4.1 lbs. Channel

    3.  Minimum column supports shall be 2" diameter standard weight
        pipe and coordinated with roofing penetration requirements.

## 2.05 SEALANTS

A.  Self-adhering vinyl coated fabric duct tape is not permitted, except
    to temporarily seal the duct openings for contamination prevention.

```{=html}
<!-- -->
```
H.  Outdoor Ducts (without exterior insulation):

    1.  Polymeric rubber, resins, and reinforcing materials dispersed in
        solvent: 24 hour cure time, UV resistant, operational
        temperature range of -20 to +150 °F, manufactured by United
        McGill, type Uni-Weather or approved equal.

I.  Indoor Ducts and Outdoor Ducts with Exterior Insulation:

    1.  Ductwork: Water based, vinyl acrylic polymeric sealant;
        nonflammable; fire retardant; operational temperature range of
        -25 to 200 °F, 48 hour cure time. Manufactured by Ductmate, type
        Pro-Seal or approved equal.

    2.  Pressurized Ductwork: Ductwork that is to be sealed while under
        pressure shall be sealed with water based mastics with
        fiberglass reinforcing and with short curing times. Manufactured
        by Versa Grip, type 102 (Hard Cast) or approved equal.

J.  Fire Stopping: Seal ductwork penetrations to halt the spread of
    fire, water and smoke through firewalls and floors and as indicated
    on contract drawings with fire resistant sealant. Maximum allowable
    flame spread, as tested by ASTM E814, is 25 with a smoke-developed
    rating no higher than 50. Fire stopping materials shall be in
    accordance with Section 07270, "Firestop and Smokestop Systems":

## 2.06 ACCESS DOORS

A.  Duct Access Door shall be factory fabricated, galvanized steel,
    double skin, and insulated. Door shall conform to SMACNA HVAC Duct
    Construction Standards and shall be hinged with sash locks and
    gaskets. Access doors shall be provided adjacent to each fire
    damper, smoke damper, smoke detector, and control device and for any
    additional locations shown on the drawings. The opening size shall
    be large enough to permit maintenance and resetting of the device.

```{=html}
<!-- -->
```
K.  Plenum Access Door shall be double wall constructed per SMACNA Duct
    Construction Standards Metal and Flexible for casing Access Doors --
    3-10" W.G. Doors shall 20 inches wide unless shown otherwise on the
    drawings and doors shall open against the air pressure.

## 2.07 LOUVERS

A.  Construction: Louvers shall have the maximum free area (minimum 50%
    of nominal size) and minimum pressure drop for each type as listed
    on the drawing louver schedule and shall be manufactured from
    6063-T6 aluminum, or 18 gage galvanized steel and finished with
    Kynar. Slats shall be inclined at least 45 degrees from the
    horizontal and overlap a minimum of 1 inch Slats over 48 inches
    shall have intermediate supports. An integral rain channel shall be
    formed with the slats. Louvers shall include a ½-3/4 inch mesh
    galvanized steel or aluminum bird screen. Louvers shall be
    compatible with the adjacent substrate.

# PART 3 - EXECUTION

## 3.01 EXAMINATION

A.  Construct and install ducts to SMACNA HVAC Duct Construction
    Standards Metal and Flexible, SMACNA Round Industrial Duct
    Construction Standards, or SMACNA Rectangular Industrial Duct
    Construction Standards (as per Part 2 "Products") and this
    specification.

```{=html}
<!-- -->
```
L.  Ductwork installation shall not proceed, until representatives from
    the other contracting trades have been consulted to ensure that
    there are no layout or installation conflicts, unless otherwise
    directed by the SDR.

M.  Structural conditions of the building may indicate that
    modifications to the ductwork are necessary. Dimensions on drawings
    indicate free inside area. Actual duct dimensions may need to be
    altered for insulation allowance when required. Ducts shall be
    transitioned or divided as may be required; whenever this is
    necessary, the equivalent area shall be maintained. Such corrections
    shall be approved and directed by the SDR, before modifications are
    started.

N.  Exit passageways, stairs, ramps and other exits shall not be used as
    a part of the air return, supply or exhaust.

O.  Installation and workmanship shall be such that the system is free
    from buckling, warping, breathing (oil canning), and vibration.
    Installation must conform to the requirements set forth in NFPA 90A
    and 90B.

## 3.02 PREPARATION

A.  Open ends of ducts shall be covered and sealed with duct tape during
    installation to prevent debris from contaminating system.

## 3.03 INSTALLATION

A.  Flexible Ducts:

    1.  Provide flexible duct in fully extended condition, free from
        kinks.

    2.  Use only the minimum length required to make the connection.

    3.  Do not exceed 5\'-0\" in length, fully extended.

    4.  Where horizontal support is required, hanger or saddle material
        shall be wide enough so that it does not reduce the internal
        diameter of the duct and shall be a minimum 1\" wide banding
        material hangers at not more than 2'-6" centers. Maximum
        allowable sag ½" per foot of support spacing. Flexible duct
        shall extend straight for several inches from a connection
        before bending.

    5.  Make joints and connections with 1/2\" wide positive locking
        steel, nylon or plenum rated straps. Connections shall be per
        SMACNA Duct Construction Standards.

    6.  Use insulated flex where insulated duct is required.

```{=html}
<!-- -->
```
P.  Metal Ductwork:

    1.  Install with a minimum of 4\" separation from earth to the duct
        or insulation finish.

    2.  Securely fasten at each change in direction.

    3.  Install branch connections and couplings tight to the duct wall
        surface with a minimum of projection into duct. Secure with
        sheet metal screws at intervals of 12 inches with a minimum of 3
        screws in each connection.

Q.  Underground Ducts: Use PVC coated galvanized steel for underground
    ducts and install in accordance with the manufacture's requirements.
    Repair damage to PVC coatings with manufacture's recommended
    materials.

    1.  Duct in concrete slabs shall be round and encased in at least
        2\" of concrete.

    2.  Use a vibrator to fill voids in concrete

R.  Insulation: Shall be installed as detailed in Section 15081, \"Duct
    Insulation.\" The insulation, facings, tapes and adhesives applied
    to the exterior surfaces of ducts located within the buildings shall
    have a composite flame spread of 25 or less and a smoke developed
    rating of 50 or less.

S.  Sealing Ductwork:

    1.  0\"-2\" w.g. classification: Transverse joints shall be sealed
        as per SMACNA guidelines for Seal Class C using products listed
        in Section 2.

    2.  Greater than 2\" w.g. positive or ½" negative classification:
        Joints, seams and penetrations shall be sealed as per SMACNA
        guidelines for Seal Class A. The shop procedure for sealing
        ducts shall be equivalent to the following: before fittings and
        joints are assembled, duct adhesive shall be applied, using a
        pump-type oil can, to rivets, grooved seams, and tap-off collars
        on the internal side of the metal. Pittsburgh lock pocket shall
        be flooded with adhesive, using pump-type oil can, and the duct
        assembled. Duct sealer shall be brushed around reinforcing
        corners, rivets, notches and tap-off collars after duct is
        assembled. Where joints are not accessible for proper sealing,
        hand holes should be cut in the duct and joints sealed from the
        inside. Fabricate hand hole covers and cover the holes with
        insulation. Special care shall be taken to seal all duct
        corners.

    3.  Stainless steel exhaust ductwork: Joints to be continuously
        welded.

## 3.04 GAS FIRED EQUIPMENT

A.  Combustion air and venting of gas-fired equipment shall conform to
    the requirements of the International Mechanical Code.

## 3.05 DUCT LINERS

A.  Install duct liners at locations as shown on the drawings and in
    accordance with NAIMA Fibrous Glass Duct Liner Standard. Apply with
    a single layer of indicated thickness.

```{=html}
<!-- -->
```
T.  Do not install liners within 24" of evaporative cooling equipment,
    across fire dampers, or within 3' down stream of duct humidifiers.

U.  Apply adhesive coating to all exposed edges of liner that do not
    receive nosing treatment.

V.  Metal nosing shall be installed over exposed liner edges that face
    upstream of the airflow.

## 3.06 HANGERS AND SUPPORTS

A.  Metal strapping for supporting and hanging ductwork and VAV boxes
    may be attached to metal roof decks with the following conditions;

    1.  The metal roof deck is 22 gauge or heavier.

    2.  For round ductwork 18 inch diameter or less and rectangular
        ductwork having a perimeter of 96 inches or less and duct
        thickness of 20 gauge or lighter.

    3.  Metal strapping must be attached to the side flute of the metal
        deck with one each No. 10 Buildex screw (or other equal load
        rated fastener) at each end for U-shaped straps and two each No.
        10 screws for single point attachments.

    4.  VAV boxes weighing 110 lbs. or less. VAV boxes shall be
        supported separately from ductwork and piping.

```{=html}
<!-- -->
```
W.  Hangers shall be installed plumb and shall present a neat
    appearance.

X.  Strap hangers shall extend the full depth of the duct, bend and
    extend 1 inches under and against the bottom of the duct.

Y.  Attach hangers to the ducts using rivets or screws of appropriate
    sizes 6 inches on center (minimum of 2 each side) and on the bottom
    return.

Z.  All ducts shall be rigidly supported.

    1.  Where vertical ducts pass through floors or roofs, supporting
        angles shall be attached to ducts and to the structure.

    2.  Place supporting angles on at least two sides of the duct.

A.  Reference Section 2 for Hangers and Supports construction and
    spacing data.

## 3.07 CONNECTORS

A.  Provide flexible connections, not less than 4 inches wide,
    constructed of approved fireproof, waterproof, non-asbestos, glass
    fabric, at the inlet and outlet connection of each fan unit,
    securely fastened to the unit and to the ductwork by a galvanized
    iron band provided with tightening screws. There shall be no
    metal-to-metal contact at flexible connections. There shall be no
    stretching of the flexible material at flexible connections. This
    connection shall be UL listed, to meet NFPA 90 requirements and the
    following applications;

    1.  Indoor Supply/Return Air: Neoprene coated glass fabric, minimum
        30 oz./sq.yd., Ventfabrics - "Ventglas" or DuroDyne -
        "Neoprene".

    2.  Outdoor Supply/Return Air: U.V. resistant Hypalon coated glass
        fabric, minimum 24 oz./sq.yd. Ventfabrics -- "Ventlon" or
        DuroDyne -- "Durolon".

    3.  Laboratory/Chemical Exhaust: Teflon coated glass fabric, minimum
        16 oz./sq.yd., Ventfabrics -- "Ventlel".

## 3.08 DAMPERS

A.  Fire and Smoke Dampers:

    1.  Dampers shall be installed in a sheet-metal collar which shall
        be reinforced with angle-iron frames. Dampers shall be installed
        according to SMACNA Fire, Smoke and Radiation Damper
        Installation for HVAC Systems and the manufactures requirements.

    2.  Provide access doors at all fire damper locations. Access doors
        shall be located so that the spring catch is accessible when the
        damper is closed.

    3.  Fire dampers shall be supported independent of ductwork in the
        ceiling, wall or floor, as conditions at the site dictate.

    4.  Fire dampers shall not be installed in exhaust systems.

    5.  Duct Connectors: Ducts shall be connected to fire and smoke
        dampers with slip joints so that the damper will remain within
        the fire barrier, even if the duct should collapse.

```{=html}
<!-- -->
```
B.  Balancing Dampers: Shall be installed where shown on drawings and as
    may be required to balance system.

C.  Control Dampers: Control dampers shall be furnished under section
    13493 -- Facilities Control System and as listed on the drawings.

## 3.09 ACCESS DOORS

A.  Duct Access Doors: Provide in locations indicated on drawings and as
    required to properly and easily service, maintain, and inspect duct
    coils, fire dampers and other equipment.

```{=html}
<!-- -->
```
D.  Plenum Access Doors:

    1.  Doors shall be provided with a flat iron or angle iron
        stiffening frame and so constructed that they can be operated
        without twisting or distorting.

    2.  The opening at each door shall be provided with a continuous
        reinforcing galvanized bar or angle against which the door will
        close, and be provided with a sponge rubber gasket to make the
        door opening airtight.

    3.  Walk through type doors at plenum chambers shall meet the
        requirements of SMACNA HVAC Duct Construction Standards -- Metal
        and Flexible

## 3.10 PLENUMS

A.  Panels shall be assembled by interlocking the flanged end with the
    double standing seam and bolting on 18\" centers. Seams shall
    project into the airside of the apparatus casings. Sealer shall be
    poured into, or plenum tape wrapped around the double seam prior to
    assembly. Joint shall be assembled immediately after sealer is
    applied. Paint outside of seam with sealer and allow 24 hours to dry
    before applying air pressure.

```{=html}
<!-- -->
```
E.  Panels shall be braced rigidly in place by 1-1/2\" x 1-1/2\" x 1/8\"
    angles spaced on 4\'-0\" centers maximum and run continuous for the
    full length or width of the casings.

F.  Casings shall be secured to concrete curbs on floors, or walls by a
    2\" x 2\" x 3/16\" toe angle, gasketed between the casing and the
    toe angle and gasketed or grouted between the toe angle and the
    floor. The toe angles shall be secured to the floor or wall by 1/4\"
    bolts 1\' -0\" o.c., shot into the floor or the wall or 1/4\" \"J\"
    bolts set in concrete 1\'-0\" o.c., through the flange angles of the
    panels. The toe angles shall run continuously for the full length of
    the casing in contact with the floor or wall. Seal joints airtight
    with sealer.

G.  Rivets and bolts through the casing shall be gasketed.

H.  Casings shall be constructed according to SMACNA HVAC Duct
    Construction Standards - Metal and Flexible.

## 3.11 DUCT PENETRATIONS

A.  Ducts through masonry openings and along edges of all plenums at
    floors and walls, shall be provided with a continuous 2\" x 2\" x
    1/8\" galvanized angle iron which shall be bolted to the
    construction and made airtight to the same by applying silicone
    caulking compound. Sheet metal at these locations shall be bolted to
    the angle irons.

```{=html}
<!-- -->
```
I.  Ducts through drywall or plaster walls and ceilings shall be
    finished with a 22 gage galvanized steel flange neatly installed.

## 3.12 LOUVERS

A.  Install storm louvers at air openings in the outside walls where
    indicated on the drawings. The exterior face of the louver shall
    have a flange all around, neatly fitted to the building wall,
    flashed at top and all sides caulked. On the outside face of each
    louver, install a removable screen, consisting of 1/2\" mesh,
    galvanized wire screen in a galvanized channel frame.

## 3.13 FILTERS AND GAUGES

A.  Filters: Furnish and install filters as scheduled on the drawings.
    Follow manufacturer\'s directions for installing each type of
    filter. The filters shall be installed such that there will be no
    leakage around the filter banks. Filters in frame holders shall be
    provided with lift handles. Hinged access panels or doors shall be
    installed for convenient access to each filter section. Filter
    retainer frames shall be arranged to provide proper support to
    facilitate each filter fitting tightly in place with provision to
    seal properly. Provide reinforcement as required such that there is
    no more than two inches of deflection across the filter rack during
    operation. Clean filters shall be installed before Test and Balance
    is begun. Filters banks shall be located in a convenient and
    accessible place, so that it can be serviced without the use of a
    stepladder. If this is impractical, install a permanent ladder or
    scaffolding for ease of service.

```{=html}
<!-- -->
```
J.  Filter gauges: Furnish and install Magnehelic gauges for the
    measurement of airflow resistance through the filters at each bank
    of filters. Furnish each gauge with two 3-way ball valves for
    venting and gauge adjustment.

## 3.14 INSPECTION AND TESTING

A.  The Contractor shall be responsible for providing a joint and
    cooperative effort to coordinate the test and balance as specified
    in Section 15901, "System Component Checkout and Balance."

```{=html}
<!-- -->
```
K.  Inspection: The contractor shall ensure that filters, dampers,
    louvers, gauges, electrical components and other accessories
    referenced in this document are installed correctly and system is
    operating in compliance with requirements prior to start-up and
    request for final inspection.

L.  Testing: Ductwork rated 4\" w.g. and higher, laboratory exhaust
    ducts and ductwork indicated on the contract documents shall be
    tested for leaks. Testing is not required for other ductwork rated 0
    to 3 \" w.g.

    1.  Testing shall be done following guidelines in SMACNA-HVAC Duct
        Leakage Test Manual.

## 3.15 CLEANING

A.  Ductwork shall be cleaned as it is being installed, to remove oil
    film and dust allowing sealants, such as silicone caulk, to cure
    before duct is cleaned and sealed.

END OF SECTION