SECTION 15890 PART I - GENERAL 1.01 WORK INCLUDED A. Types of ductwork required for this project include the following: 1. Sheet Metal Ductwork 2. Flexible Ductwork 3. Air Plenums B. Construct all ductwork located between air handling unit and variable air volume boxes for 4 w.g. pressure class per SMACNA requirements and as listed herein. C. Construct all other ductwork for 2 w.g. pressure class, except as noted, per SMACNA requirements. 1.02 QUALITY ASSURANCE A. Installer: A firm with at least three years of successful installation experience on projects similar to that required for this work. 1. For work on fiberglass ductwork provide statement from manufacturer indicating that the manufacturer accepts this fabricator to be a qualified fabricator. 2. No fiberglass ductwork; no fiberglass in air stream. B. SMACNA Compliance: Comply with applicable portions of Sheet Metal and Air Conditioning Contractor's National Association (SMACNA) for all work in this section. C. ASHRAE Standards: Comply with American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE) recommendations, latest edition, for all work in this section. D. NFPA Compliance: Comply with ANSI/NFPA 90A, "Standard for the Installation of Air Conditioning and Ventilating Systems," and ANSI/NFPA 90B, "Standard for the Installation of Warm Air Heating and Air Conditioning Systems." E. Patch, repair or replace ductwork as required. All ductwork shall be made airtight with 1% maximum or less leakage of design flow. Repair or replace ducts and joints as required to the satisfaction of the University's Representative. 1.03 SUBMITTALS A. Product Data: Submit manufacturer's specifications on manufactured products and factory-fabricated ductwork, used for work of this section. B. Record Drawings: At project close-out, submit Record Drawings of installed ductwork, duct accessories, and outlets and inlets in accordance with requirements of Division 1. 15890-1
PART II - MATERIALS 2.01 GENERAL A. All standing seams and transverse joints in ALL sheet metal ductwork shall be covered with 4 wide strip of 6-ounce canvas and lagging adhesive to assure airtight joints. Pressure-sensitive tapes not acceptable. B. No interior duct liner accepted. 2.02 TWO-INCH PRESSURE CLASS MATERIALS A. Sheet Metal Ductwork: Except as otherwise indicated, fabricate ductwork with commercial grade of galvanized steel. B. External Duct Lining: 1. Provide external duct lining only: 2. Oversize duct to maintain low pressure. C. Round supply ductwork shall be of the same materials, gauges, and construction as that indicated for 4 pressure class ductwork. D. Ductwork Support Materials: Except as otherwise indicated, provide hot-dipped galvanized steel fasteners, anchors, rods, straps, trim, and angles for support of ductwork. 2.03 TWO-INCH PRESSURE CLASS FABRICATION A. Shop fabricate ductwork in 4-, 8-, 10- or 12-foot lengths, unless otherwise indicated or required, to complete runs. Pre-assemble work in shop to greatest extent possible, so as to minimize field assembly of systems. Disassemble systems only to extent necessary for shipping and handling. Match-mark sections for reassembly and coordinated installation. B. Shop fabricate ductwork of gauges and reinforcement complying with SMACNA HVAC Duct Construction Standards, latest edition. C. Fabricate duct fittings to match adjoining ducts and to comply with duct requirements as applicable to fittings. Except as otherwise indicated, fabricate elbows with center-line radius equal to 1.5 times associated duct width and fabricate to include turning vanes in elbows where shorter radius is necessary. Limit angular tapers to 30º for contracting tapers and 20º for expanding tapers. D. Fabricate ductwork with accessories installed during fabrication to the greatest extent possible. Refer to Division 15, Section 15910 Duct Accessories for accessory requirements. E. Fabricate round supply connections at rectangular, plenum-type fittings using spin-in type fittings, complete with extractor and volume control damper. 1. Provide spiral-lock seam prefabricated duct, as specified for 4 pressure class. Longitudinal seam duct shall not be used. 15890-2
2.04 FOUR-INCH PRESSURE CLASS A. Sheet Metal: Except as otherwise indicated, fabricate ductwork with commercial grade of galvanized sheet steel. 2.05 FACTORY-FABRICATED, FOUR-INCH PRESSURE CLASS A. Spiral lock seam prefabricated factory-build round and oval duct and fittings shall be used wherever possible. Shop-fabricated ducts shall be used only where rectangular shaped ducts are shown on plans or where transitions and special fittings cannot be prefabricated by factory. B. Round Ductwork: Construct of galvanized sheet steel complying with ANSI/ASTM A 527 by the following methods and in minimum gauges listed. 1. DIAMETER MINIMUM GAUGE METHOD OF MANUFACTURE 3" to 14" 26 Spiral Lockseam 15" to 26" 24 Spiral Lockseam 27" to 36" 22 Spiral Lockseam 37" to 50" 20 Spiral Lockseam 51" to 60" 18 Spiral Lockseam Over 60" 16 Longitudinal Seam C. Provide locked seams for spiral duct; fusion-welded butt seam for longitudinal seam duct. D. Fittings and Couplings: Construct of minimum gauges listed. Provide continuous welds along seams. 1. DIAMETER MINIMUM GAUGE 3" to 36" 20 38" to 50" 18 Over 50" 16 E. Flat-Oval Ductwork: Construct of galvanized sheet steel complying with ANSI/ASTM A 527, of spiral lockseam construction, in minimum gauges listed. 1. MAXIMUM WIDTH MINIMUM GAUGE Under 25" 24 25" to 48" 22 49" to 70" 20 Over 70" 18 F. Fittings and Couplings: Construct of minimum gauges listed. Provide continuous weld along seams. 1. MAXIMUM WIDTH MINIMUM GAUGE Under 37" 20 37" to 50" 18 Over 50" 16 15890-3
G. Manufacturers: 1. MANUFACTURER PRODUCT United Sheet Metal Div., United Magill Corp. Semco Manufacturing Incorporated Air Systems Incorporated - Las Vegas Or equal 2.06 MISCELLANEOUS MATERIALS Uniseal A. Provide miscellaneous materials and products of types and sizes indicated, and where not otherwise indicated, provide requirements as listed in the latest SMACNA manuals, including proper connection of ductwork and equipment. B. Fittings: Unless otherwise shown on Drawings, following fittings shall be used: two-piece, die-stamped, 45º to 90º elbows for sizes up to 8 ; five-piece, 90º elbows for sizes over 8 ; conical tees; and conical laterals. All reducers shall be placed after a tap has been made on the duct main. Reducers shall be long-taper style. C. Duct Sealant: Non-hardening, non-migrating mastic or liquid elastic sealant as compounded and recommended by manufacturer specifically for sealing joints and seams in ductwork. D. Duct Joints: Joint and seal prefabricated, factory-built ducts, fittings, and couplings in strict accordance with duct manufacturer's instructions. Install duct sealers, pop rivets or sheet metal screws and canvas and apply adhesive sealant, Foster SEALFAST, Hardcast Flex-Grip, Childers Chil-Perm or equal, on each joint. Duct sealer shall be fire retardant. Sheet metal screw for joints shall be minimum #10 size galvanized. E. Duct Access: Provide access panel sections in prefabricated, factory-built ducts for access to fire dampers, control equipment, etc. as specified in Duct Accessories Section. Access panel size shall be duct diameter wide by duct diameter high for all ducts under 24. Ducts over 24 in diameter shall have 24 x 18 access panels. Minimum size access panels shall be 6 x 6. 2.07 FLEXIBLE DUCTS A. Flexible ducts may be used in concealed areas only. B. Factory insulate all flexible ducts with 1 thick, one- pound density fiberglass insulation and wrap with factory-installed vapor barrier jacket. Ducts shall be UL approved and tested and meet Class 1 requirements of NFPA 90A. Make elbows to maintain R/W-1.5. C. Flexible ducts from rigid runouts to registers shall be Thermaflex M-KE, or equal, with maximum length of seven (7) feet. Flexible duct shall have no bends greater than 45º. D. Flexible ducts shall consist of an exterior reinforced laminated vapor barrier, 1-½ thick fiberglass insulation (K=.25 @ 75ºF), encapsulated spring steel wire Helix and impervious, smooth, non-perforated interior vinyl liner. Individual lengths of flexible ducts shall contain factory-fabricated steel connection collars. 1. Make connections to rigid duct and units with draw band and sealer, and then duct tape over outside of sheath. 15890-4
2.08 AIR PLENUMS 2. Minimum bend radius shall be twice the duct diameter. 3. Insulated flexible duct shall be attached to collar with a worm drive draw band rated for 175 pounds and inserted a minimum of 1 on to collar. Securely attach insulation and vapor barrier to the collar using a second worm drive draw band rated at 175 pounds. The vapor barrier shall be drawn over the insulation and fastened by the draw band such that no raw insulation is exposed. A. Construct air plenums designated on the Drawings of factory-fabricated panels or by Contractor-fabrication. In either case, provide all plenum enclosures in this work. B. Factory-fabricated panels shall be 4 thick. Industrial Acoustics, United Sheet Metal, or equal. Panels shall be constructed of 20-gauge (min.) galvanized steel solid panels. Entire plenum shall be sealed and caulked airtight in accordance with manufacturer's instructions. Framing members manufactured by panel manufacturer shall be used throughout and connected to base with preset studs with sheet metal screws through framing members as recommended by manufacturer. Plenum shall provide structural rigidity to a minimum of 4 VC pressure differential, either positive or negative. C. Fabricate Contractor fabricated panels as recommended by SMACNA Duct Construction Standards for 4 pressure differential. PART III - EXECUTION 3.01 INSTALLATION OF A. Assemble and install ductwork in accordance with recognized industry practices which will achieve air tight (leakage class 12 for 2 pressure class and leakage class 3 for 4 pressure class) and noiseless (no objectionable noise) systems capable of performing each indicated service. Install each run with minimum of joints. Align ductwork accurately at connections within ⅛ misalignment tolerance and with internal surfaces smooth. Support ducts rigidly with suitable ties, braces, hangers, and anchors of type which will hold ducts true to shape and to prevent buckling. B. Seal ductwork after installation to seal class required and method prescribed in SMACNA "HVAC Leakage Test Manual," latest edition. C. Install concrete inserts for support of ductwork in coordination with formwork as required to avoid delays in work. D. Where ducts pass through interior partitions and exterior walls, conceal space between construction opening and duct or duct-plus- insulation with sheet metal flanges of same gauge as duct. Overlap opening on four sides by at least 1-½. E. Support ductwork in manner complying with SMACNA "HVAC Duct Construction Standards," latest edition, hangers and supports sections. Where special hanging of ductwork is detailed or shown on Drawings, Drawings shall be followed. Angles shall be attached to overhead construction in a manner so as to allow a minimum of 2 of movement in all directions with no bending or sagging of the angle. F. Balancing dampers shall be installed in all branch ducts and elsewhere as indicated on the drawings. 15890-5
G. Use radius elbows in rectangular ducts unless otherwise indicated. Square turn in rectangular ductwork at following locations: immediately upstream from supply air outlets. When required to facilitate installation. Do not install one square turn immediately after another. H. All duct work on the high-pressure side of any seam 4" of water or higher shall use government clip or clip and flange with canvas and apply adhesive sealant on each connection. I. Medium pressure ductwork (from fan discharge to CAV inlet); Extreme care shall be used in the fabrication and installation of the medium pressure ductwork to insure that it will be airtight. All ductwork shall be tested for leaks in sections as soon as possible and before any insulating. J. Medium pressure duct: cap section ends and pressurize to 1-½ times fan static pressure, minimum 4 WC to 10 minutes. K. All duct except medium pressure duct: Cap section ends and pressurize to 2" W.C. for 10 minutes. L. Do not use flexible duct to connect to any air distribution device or terminal unit (with the exception of registers). Use flex connections where required by code or design for terminal units. M. Provide access doors at each change in direction requiring turning vanes, at bottom of risers, and every 50 in horizontal runs. Provide access doors in inaccessible ceilings and walls to gain access to all dampers, terminal units, coils, filters, valves, air vents, control devices, traps, cleanouts and other similar devices requiring periodic observation adjustment, service or replacement. N. Exact location of each access door shall be determined prior to installation and such information shall be submitted to University's Representative for review an approval. Ceiling access doors shall be no less than 24" x 24" and wall access doors shall be sized to suit equipment, but not less than 12" x 12". 3.02 TESTING FOUR-INCH PRESSURE CLASS AND PLENUMS A. Contractor to test all pressure ductwork and plenums for leaks using a portable highpressure blower and necessary instrument. Extreme care shall be used in fabrication and installation of ductwork to ensure that it will be airtight. All ductwork shall be tested for leaks in sections as work progresses and as directed by University's Representative. Section to be tested shall have all open ends sealed off and shall then be tested using the following method: 1. Orifice Flow Test: Equipment required for this testing comprises a high-pressure blower, orifice test pipe assembly, and manometer with necessary valves and tubing. All testing shall be in conformance with SMACNA "HVAC Air Duct Leakage Test Manual," latest edition. Ductwork section being tested shall be held under a constant pressure of 4 of water with blower while any leakage flow through orifice is measured on manometer. Manometer readings shall be converted to CFM from a calibrated test curve. Leakage shall not exceed one percent of design air flow with a maximum allowable of 500 CFM. Complete information and data on equipment to be used must be submitted to University's Representative for approval before any tests are made. 15890-6
B. Testing of any completed section of ductwork must be made before installation of finished ceiling, if any, or before ductwork is furred in inaccessible spaces and must be witnessed by University's Representative. Any leaks found must be properly repaired or joints remade, and section re-tested until tight. Leaks which cause any objectionable noise must be repaired, regardless of amount of leakage. C. Upon completion of testing, the Contractor shall complete the test report forms provided by SMACNA "HVAC Air Duct Leakage Test Manual." These forms shall be made in triplicate and forwarded to the University's Representative for review. 3.03 CLEANING AND PROTECTION A. Clean ductwork internally, unit by unit as it is installed, of dust and debris. Clean external surfaces of foreign substances which might cause corrosive deterioration of metal or where ductwork is to be painted. B. Temporary Closure: At ends of ducts which are not connected to equipment or air distribution devices at time of ductwork installation, provide temporary closure of polyethylene film or other covering which will prevent entrance of dust and debris until time connections are to be completed. 3.04 OPERATION TEST A. Test each piece of equipment to show that it will operate in accordance with indicated requirements. 3.05 CLEANING UP A. Upon completion of Work remove materials, equipment, apparatus, and tools, and leave premises clean, neat, and orderly. B. Ductwork: Examine air-handling systems and clean any obstruction and debris. With dampers wide open and closed, run fan systems and check for air leaks. C. All distribution equipment shall not be operated until the building is cleaned. END OF SECTION 15890 15890-7