PART 1 GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Specification Sections, apply to this Section. B. Related Sections: 1.2 SUMMARY 1. Section 09900 Painting : Execution requirements for Weld priming, weather resistant, paint or coating specified by this section. 2. Section 15060 Hangers and Supports : Product requirements for hangers, supports and sleeves for placement by this section. 3. Section 15950 Testing, Adjusting, and Balancing. 4. Section 15074 Vibration and Seismic Controls for HVAC Piping and Equipment. 5. Section 15075 Mechanical Identification. 6. Section 15080 Mechanical Insulation. A. This Section includes rectangular, round, and flat-oval metal ducts and plenums for heating, ventilating, and air-conditioning systems in pressure classes from minus 2 inch w.g. to plus 10-inch w.g. 1.3 REFERENCES A. ASTM A36 - Structural Steel. B. ASTM A90 - Weight of Coating on Zinc-Coated (Galvanized) Iron or Steel Articles. C. ASTM A167 - Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip. D. ASTM A366 - Steel, Sheet, Carbon, Cold Rolled, Commercial Quality. E. ASTM A568 - Steel, Sheet, Carbon, and High-Strength, Low-Alloy, Hot-Rolled and Cold-Rolled. F. ASTM A569 - Steel, Carbon (0.15 Maximum, Percent), Hot-Rolled Sheet and Strip, Commercial Quality. G. ASTM B209 - Aluminum and Aluminum-Alloy Sheet and Plate. H. NFPA 90A (National Fire Protection Association) - Installation of Air Conditioning and Ventilating Systems. I. NFPA 90B (National Fire Protection Association) - Installation of Warm Air Heating and Air Conditioning Systems. J. SMACNA (Sheet Metal Air Conditioning Contractors National Association) - HVAC Air Page 1 of 14
Duct Leakage Test Manual. K. SMACNA (Sheet Metal Air Conditioning Contractors National Association) - HVAC Duct Construction Standards - Metal and Flexible. L. UL 181 (Underwriters Laboratories, Inc.) - Factory-Made Air Ducts and Connectors. 1.4 DEFINITIONS A. Thermal Conductivity and Apparent Thermal Conductivity (k-value): As defined in ASTM C 168. In this Section, these values are the result of the formula Btu x in./h x sq. ft. x deg F or W/m x K at the temperature differences specified. Values are expressed as Btu or W. 1. Example: Apparent Thermal Conductivity (k-value): 0.26 or 0.037. 1.5 SYSTEM DESCRIPTION A. Duct system design, as indicated, has been used to select and size air-moving and - distribution equipment and other components of air system. Changes to layout or configuration of duct system must be specifically approved in writing by the Owner. Accompany requests for layout modifications with calculations showing that proposed layout will provide original design results without increasing system total pressure. 1.6 SUBMITTALS A. Product Data: For duct liner and sealing materials. B. Shop Drawings: Show details of the following: 1. Fabrication, assembly, and installation, including plans, elevations, sections, components, and attachments to other work. 2. Duct layout indicating pressure classifications and sizes on plans. 3. Fittings. 4. Reinforcement and spacing. 5. Seam and joint construction. 6. Penetrations through fire-rated and other partitions. 7. Terminal unit, coil, and humidifier installations. 8. Hangers and supports, including methods for building attachment, vibration isolation, seismic restraints, and duct attachment. C. Coordination Drawings: Reflected ceiling plans drawn to scale and coordinating penetrations and ceiling-mounted items. Show the following: 1. Ceiling suspension assembly members. 2. Other systems installed in same space as ducts. 3. Ceiling- and wall-mounted access doors and panels required to provide access to dampers and other operating devices. 4. Coordination with ceiling-mounted items, including lighting fixtures, diffusers, grilles, speakers, sprinkler heads, access panels, and special moldings. D. Welding Certificates: Copies of certificates indicating welding procedures and personnel comply with requirements in "Quality Control" Article. Page 2 of 14
E. Field Test Reports: Indicate and interpret test results for compliance with performance requirements. F. Record Drawings: Indicate actual routing, fitting details, reinforcement, support, and installed accessories and devices. 1.7 QUALITY CONTROL A. All ductwork shall be constructed in accordance with the latest issue of the applicable Sheet Metal and Air Conditioning Contractors National Association (SMACNA), Inc., "HVAC Duct Construction Standards" and "Industrial Duct Construction Standards". B. Zinc-coated metal shall be in accordance with ASTM A525. C. Aluminum alloy shall be in accordance with ASTM B209, mill finish. D. Welding Standards: Qualify welding procedures and welding personnel to perform welding processes for this Project according to AWS D1.1, "Structural Welding Code-- Steel," for hangers and supports; AWS D1.2, "Structural Welding Code--Aluminum," for aluminum supporting members; and AWS D9.1, "Sheet Metal Welding Code," for duct joint and seam welding. E. Comply with NFPA 90A, "Installation of Air Conditioning and Ventilating Systems," unless otherwise indicated. F. Comply with NFPA 90B, "Installation of Warm Air Heating and Air Conditioning Systems," unless otherwise indicated. G. Comply with NFPA 96, "Ventilation Control and Fire Protection of Commercial Cooking Operations," Chapter 3, "Duct System," for range hood ducts, unless otherwise indicated. H. Mockups: Before installing duct systems, erect mockups representing system pressure classifications higher than 2-inch wg. Build mockups to comply with the following requirements, using materials indicated for completed Work: 1. Locate mockups in the locations and of the size indicated or, if not indicated, as directed by Architect. Mockup may be a representative section of the actual duct system. 2. Include the minimum number of each of the following features and fittings: a. Five transverse joints. b. One access door. c. Two typical branch connections, each with at least one elbow. d. Two typical flexible duct or flexible connector connections for each duct and apparatus. 3. Perform tests specified in "Field Quality Control" Article. Modify mockup construction and perform additional tests as required to achieve specified minimum acceptable results. 4. Obtain McCarran International Airport s approval of mockups before starting Work. 5. Maintain mockups during construction in an undisturbed condition as a standard for judging the completed Work. 6. When directed, demolish and remove mockups from Project site. Page 3 of 14
7. Approved mockups in an undisturbed condition at the time of Substantial Completion may become part of the completed Work. 1.8 DELIVERY, STORAGE, AND HANDLING A. Deliver sealant and firestopping materials to site in original unopened containers or bundles with labels indicating manufacturer, product name and designation, color, expiration period for use, pot life, curing time, and mixing instructions for multi-component materials. B. Store and handle sealant and firestopping materials according to manufacturer's written recommendations. C. Deliver and store stainless-steel sheets with mill-applied adhesive protective paper maintained through fabrication and installation. PART 2 - PRODUCTS 2.1 DUCTWORK PRESSURE CLASSIFICATIONS A. The following are lists of ductwork construction pressure classifications to be used on this project. Where ductwork pressure class is not stated, the duct system shall be constructed to the static pressure classification which exceeds the fan shut-off pressure. B. SMACNA + 0.5" w.g. static pressure class and 2000 FPM maximum velocity. C. SMACNA - 0.5" w.g. static pressure class and 2000 FPM maximum velocity. D. SMACNA + 1.0" w.g. static pressure class and 2500 FPM maximum velocity. 1. All supply and make-up ducts downstream of terminal units. E. SMACNA - 1.0" w.g. static pressure class and 2500 FPM maximum velocity. 1. All return air ductwork upstream of the main branch fire or combination fire/smoke damper at the main duct riser. 2. All exhaust air ductwork and smoke exhaust ductwork unless otherwise noted. F. SMACNA + 2.0" w.g. static pressure class and 2500 FPM maximum velocity. G. SMACNA - 2.0" w.g. static pressure class and 2500 FPM maximum velocity. H. SMACNA + 3.0" w.g. static pressure class and 4000 FPM maximum velocity. I. SMACNA - 3.0" w.g. static pressure class and 4000 FPM maximum velocity. 1. Main return air duct risers from the return fan upstream to the fire dampers or combination fire/smoke dampers serving the individual floors. 2. All kitchen hood exhaust ductwork. J. SMACNA + 4.0" w.g. static pressure class and 4000 FPM maximum velocity. Page 4 of 14
1. All plenums for air handling units downstream of control dampers. 2. All supply air and make-up air ductwork from air handling units downstream to terminal units. K. SMACNA +6.0" w.g. static pressure class and 4000 FPM maximum velocity. L. SMACNA + 10.0" w.g. static pressure class and 4000 FPM maximum velocity. 2.2 MATERIALS A. All supply, return, relief, outside air and ventilating ducts for air handling units, and general exhaust systems, including casings for coils and fans, plenums, volume control dampers, vanes, baffles and duct hangers shall be constructed of galvanized steel or aluminum. B. All boiler breechings, belt guards, concealed ductwork from kitchen exhaust hoods and fabricated exhaust hoods shall be constructed of black steel sheets, hot or cold rolled. C. All Locker Room and Shower Room exhaust ducts and all goosenecks and vent ducts above roof shall be constructed of aluminum. D. All exposed ductwork in the kitchen and dishwasher rooms, kitchen hoods and dishwasher exhaust hoods shall be constructed of stainless steel. E. All exhaust ductwork from dishwashers rooms, and other exhaust ductwork conveying moist air shall be constructed of welded stainless steel. Gauge of metal shall be of a thickness suitable for welding. F. Ductwork downstream of humidifiers shall be aluminum. Refer to notes on the Drawings. 2.3 SHEET METAL MATERIALS A. Galvanized, Sheet Steel: Lock-forming quality; ASTM A 653/A 653M, G90 coating designation; mill-phosphatized finish for surfaces of ducts exposed to view. B. PVC-Coated Galvanized Steel: UL 181, Class 1 listing. Lock-forming-quality, galvanized, sheet steel with ASTM A 653/A 653M, G90 coating designation; factoryapplied, 4-mil PVC coating on exposed surfaces of ducts and fittings (exterior of ducts and fittings for underground applications and interior of ducts and fittings for fumehandling applications) and with factory-applied, 2-mil PVC coating on reverse side of ducts and fittings. C. Carbon-Steel Sheets: ASTM A 366/A 366M, cold-rolled sheets; commercial quality; with oiled, exposed matte finish. D. Stainless Steel: ASTM A 480/A 480M, Type 316, sheet form with No. 4 finish for surfaces of ducts exposed to view; and Type 304, sheet form with No. 1 finish for concealed ducts. E. Aluminum Sheets: ASTM B 209, Alloy 3003, Temper H14, sheet form with standard, one-side bright finish for ducts exposed to view and with mill finish for concealed ducts. Page 5 of 14
F. Reinforcement Shapes and Plates: Galvanized steel reinforcement where installed on galvanized, sheet metal ducts; compatible materials for aluminum and stainless-steel ducts. G. Tie Rods: Galvanized steel, 1/4-inch minimum diameter for 36-inch length or less; 3/8- inch minimum diameter for lengths longer than 36 inches. Additional Tie-Rods shall be added in addition to those required by SMACNA to insure a pulse free installation in the ductwork. 2.4 BLACK STEEL SHEETS A. Black steel sheets used in the construction of boiler breechings shall be 10 gauge material. B. Black steel sheets used in the construction of rectangular or round ductwork or exhaust hoods shall be of gauge set forth in the following schedule: 1. Rectangular ducts (longest side) Up to 24 inches 16 gauge 25 inches to 36 inches 14 gauge 37 inches to 60 inches 12 gauge Over 60 inches 10 gauge 2. Round ducts (diameter) Up to 26 inches 16 gauge 27 inches to 39 inches 14 gauge 40 inches to 65 inches 12 gauge Over 65 inches 10 gauge C. Black steel sheets used in the construction of belt guards shall be 18 gauge material. The side panels shall be expanded metal. An opening with cover shall be provided in side panel at both the motor and fan shafts for taking rpm readings. D. All seams and joints shall be continuous weld. Where seams and joints are exposed to view, in finished areas, the weld seams shall be ground to a smooth finish. 2.5 STAINLESS STEEL DUCTS OR SHEETS A. Stainless steel used in the construction of ductwork and for kitchen exhaust, and dishwashing exhaust hoods shall be Type 302 with No. 4 finish for exposed areas. B. Minimum gauges for stainless steel, type of joints and reinforcing angle sizes shall be as set forth for galvanized steel in the latest SMACNA low pressure duct construction standard. C. All stainless steel ductwork exposed to view in finished areas shall be streamlined construction having no visible standing seam, joints or angle bracing. Gauge of metal shall be of a thickness suitable for welding, and all welded joints shall be ground and polished. Page 6 of 14
D. All hoods shall be constructed having no visible standings seams, joints or angle bracing on the outer surface of the hood. Gauge of metal shall be of a thickness suitable for welding and all welded joints shall be ground and polished. E. Concealed and visible ductwork serving dishwashers shall be constructed of welded type 304 stainless steel. Gauge of metal shall be suitable for welding. Welded joints in concealed locations will not be required to be ground or polished but must be neat. Welded joints in visible locations shall be ground and polished. 2.6 DUCT LINER A. General: Comply with NFPA 90A or NFPA 90B and NAIMA's "Fibrous Glass Duct Liner Standard." B. Materials: ASTM C 1071 with coated surface exposed to airstream to prevent erosion of glass fibers. 1. Thickness: 1/2 inch. 2. Thickness: 1 inch. 3. Thickness: 1-1/2 inches. 4. Thermal Conductivity (k-value): 0.26 at 75 deg F mean temperature. 5. Fire-Hazard Classification: Maximum flame-spread rating of 25 and smokedeveloped rating of 50, when tested according to ASTM C 411. 6. Liner Adhesive: Comply with NFPA 90A or NFPA 90B and ASTM C 916. 7. Mechanical Fasteners: Galvanized steel, suitable for adhesive attachment, mechanical attachment, or welding attachment to duct without damaging liner when applied as recommended by manufacturer and without causing leakage in duct. a. Tensile Strength: Indefinitely sustain a 50-lb- tensile, dead-load test perpendicular to duct wall. b. Fastener Pin Length: As required for thickness of insulation and without projecting more than 1/8 inch into airstream. c. Adhesive for Attaching Mechanical Fasteners: Comply with fire-hazard classification of duct liner system. 2.7 SEALANT MATERIALS A. All ductwork shall be Seal Class A for all McCarran International Airport ductwork, No Exceptions. Joint and Seam Sealants, General: The term "sealant" is not limited to materials of adhesive or mastic nature but includes tapes and combinations of openweave fabric strips and mastics. 1. Joint and Seam Tape: 2 inches wide; glass-fiber fabric reinforced. 2. Tape Sealing System: Woven-fiber tape impregnated with a gypsum mineral compound and a modified acrylic/silicone activator to react exothermically with tape to form a hard, durable, airtight seal. 3. Joint and Seam Sealant: One-part, non-sag, solvent-release-curing, polymerized butyl sealant, formulated with a minimum of 75 percent solids. 4. Flanged Joint Mastics: One-part, acid-curing, silicone, elastomeric joint sealants, complying with ASTM C 920, Type S, Grade NS, Class 25, Use O. Page 7 of 14
2.11 HANGERS AND SUPPORTS A. Building Attachments: Concrete inserts, powder-actuated fasteners, or structural-steel fasteners appropriate for building materials. 1. Use powder-actuated concrete fasteners for standard-weight aggregate concretes or for slabs more than 4 inches thick. 2. Exception: Do not use powder-actuated concrete fasteners for lightweightaggregate concretes or for slabs less than 4 inches thick. B. Hanger Materials: Galvanized, sheet steel or round, threaded steel rod. 1. Hangers Installed in Corrosive Atmospheres: Electro-galvanized, all-thread rod or galvanized rods with threads painted after installation. 2. Straps and Rod Sizes: Comply with SMACNA's "HVAC Duct Construction Standards--Metal and Flexible" for sheet steel width and thickness and for steel rod diameters. C. Duct Attachments: Sheet metal screws, blind rivets, or self-tapping metal screws; compatible with duct materials. D. Trapeze and Riser Supports: Steel shapes complying with ASTM A 36/A 36M. 1. Supports for Galvanized-Steel Ducts: Galvanized steel shapes and plates. 2. Supports for Stainless-Steel Ducts: Stainless-steel support materials. 3. Supports for Aluminum Ducts: Aluminum support materials, unless materials are electrolytically separated from ductwork. 2.12 DUCTWORK CONSTRUCTION: 2.0" W.G. STATIC PRESSURE CLASS AND LESS (LOW PRESSURE) A. Minimum gauges of sheet metal, types of joints, bracing, etc. shall be as set forth in the latest edition of the SMACNA "HVAC Duct Construction Standards". Seal Class A construction is required for duct pressure classes between positive 1" w.g. and negative 1" w.g.; Seal Class A construction is required otherwise. B. Fabricate and support in accordance with SMACNA HVAC Duct Construction Standards Metal and Flexible, and as indicated. Provide duct material, gages, reinforcing, and sealing for operating pressures indicated. Adjustable elbows shall not be used. C. Construct T s, bends, and elbows with minimum radius 1-1/2 times centerline duct width. Where possible and where rectangular elbows are used, provide airfoil turning vanes. Where acoustical lining is indicated, provide turning vanes of perforated metal with glass fiber insulation. D. Increase duct sizes gradually, not exceeding 15 degrees divergence wherever possible; maximum 30 degrees divergence upstream of equipment and 45 degrees convergence downstream. Page 8 of 14
E. Fabricate continuously welded round and oval duct fittings two gages heavier than duct gages indicated in SMACNA Standard Minimum 4-inch cemented slip joint, brazed or electric welded. Prime coat welded joints. F. Provide standard 45-degree lateral wye takeoffs unless otherwise indicated where 90- degree conical tee connections may be used. 2.13 DUCTWORK CONSTRUCTION: GREATER THAN 2.0" STATIC PRESSURE CLASS (HIGH PRESSURE) A. All ductwork from static pressures greater than 2 inches w.g. and/or velocity greater than 2,500 fpm shall be considered as "high pressure" construction. B. All gauges of sheet metal, transverse joints, and bracing shall be as set forth in the latest edition of the SMACNA "HVAC Duct Construction Standards" and the SMACNA "Industrial Duct Construction Standards" with Class 1 construction. Ductwork shall be Seal Class A construction. C. All longitudinal and transverse joints shall be carefully sealed with sealing compound. Compound shall be applied both when forming joints, and when pulling joints together. When transverse joints are flanged, provide gaskets of neoprene or other suitable material between flanges. D. Fabricate and support in accordance with SMACNA HVAC Duct Construction Standards Metal and Flexible, and as indicated. Provide duct material, gages, reinforcing, and sealing for operating pressures indicated. Adjustable elbows shall not be used. E. Construct T s, bends, and elbows with minimum radius 1-1/2 times centerline duct width. Where possible and where rectangular elbows are used, provide airfoil turning vanes. Where acoustical lining is indicated, provide turning vanes of perforated metal with glass fiber insulation. F. Increase duct sizes gradually, not exceeding 15 degrees divergence wherever possible; maximum 30 degrees divergence upstream of equipment and 45 degrees convergence downstream. G. Fabricate continuously welded round and oval duct fittings two gages heavier than duct gages indicated in SMACNA Standard Minimum 4-inch cemented slip joint, brazed or electric welded. Prime coat welded joints. H. Provide standard 45-degree lateral wye takeoffs unless otherwise indicated where 90- degree conical tee connections may be used. 2.14 FACTORY FABRICATED DUCT JOINTS. A. Factory fabricated duct joint systems for rectangular or round ductwork may be used on this project in lieu of Standard SMACNA joints provided the "EI" factor for rigidity and strength exceeds the "EI" factor required by the SMACNA manual. Submit "EI" factor data for each joint proposed for use on the project along with the ductwork construction shop standards. Page 9 of 14
B. Each factory fabricated duct joint system shall be applied in full conformance with the joint manufacturer's installation instructions and with all required sealants, gaskets, bolts, and spring clips. Substitution of zip screws for spring clips will not be permitted. C. Approved factory fabricated Proprietary duct joint systems for the project are Ductmate and WDCI. 2.15 REINFORCEMENT OF SHEET METAL PLENUMS A. Sheet metal air plenums with dimensions exceeding 48" wide by 48" high, which are not part of an engineered enclosure system, shall have walls and floors reinforced with cold-formed light gauge metal framing or with bent sheet metal channel having a similar section modulus. 1. Provide wall framing on 48" centers to meet an internal pressure loading of 15 lbs. per sq. ft. (3" w.g.). Note To Contractor - This loading is similar to the load on wall framing subject to an internal pressure of 30 lbs. per sq. ft. with joists spaced at 24" centers. 2. Provide reinforcement on 24" centers at 40 lbs per sq. ft. loading for plenum floors exceeding 36" in depth. Deflection shall not exceed 1" per 240" of span. B. Submit framing dimensions and gauges on the sheet metal shop drawings. C. For plenums with a wall exceeding 15' high, furnish the services of a Civil/Structural Engineer registered in the State of Nevada to design the reinforcement framing system. The Civil/Structural Engineer shall stamp all sketches and drawings certifying that reinforcements have been properly designed. 2.16 DOUBLE WALL PLENUMS A. Provide double wall acoustical plenums where shown on the drawings and as specified. Refer to "Duct Accessories" Section for requirements. 2.17 SHOP APPLICATION OF LINER IN RECTANGULAR DUCTS A. Adhere a single layer of indicated thickness of duct liner with 90 percent coverage of adhesive at liner contact surface area. Multiple layers of insulation to achieve indicated thickness are prohibited. B. Apply adhesive to liner facing in direction of airflow not receiving metal nosing. C. Butt transverse joints without gaps and coat joint with adhesive. D. Fold and compress liner in corners of rectangular ducts or cut and fit to ensure buttededge overlapping. E. Do not apply liners in rectangular ducts with longitudinal joints, except at corners of ducts, unless duct size and standard liner product dimensions make longitudinal joints necessary. F. Apply adhesive coating on longitudinal seams in ducts with air velocity of 2500 fpm. Page 10 of 14
G. Secure liner with mechanical fasteners 4 inches from corners and at intervals not exceeding 12 inches transversely around perimeter; at 3 inches from transverse joints and at intervals not exceeding 18 inches longitudinally. H. Secure transversely oriented liner edges facing the airstream with metal nosings that have either channel or "Z" profile or are integrally formed from duct wall. Fabricate edge facings at the following locations: 1. Fan discharge. 2. Intervals of lined duct preceding unlined duct. 3. Upstream edges of transverse joints in ducts. I. For high pressure duct work defined in section 2.13.A., secure insulation liner with perforated sheet metal liner of same metal thickness as specified for duct, secured to ducts with mechanical fasteners that maintain metal liner distance from duct without compressing insulation. 1. Sheet Metal Liner Perforations: 3/32-inch diameter, with an overall open area of 23 percent. J. Terminate liner with duct buildouts installed in ducts to attach dampers, turning vane assemblies, and other devices. Fabricated buildouts (metal hat sections) or other buildout means are optional; when used, secure buildouts to duct wall with bolts, screws, rivets, or welds. Terminate liner at fire dampers at connection to fire-damper sleeve. PART 3 - EXECUTION 3.1 DUCT INSTALLATION, GENERAL A. Duct installation requirements are specified in other Division 15 Sections. Drawings indicate general arrangement of ducts, fittings, and accessories. B. Construct and install each duct system for the specific duct pressure classification indicated. C. Install round and flat-oval ducts in lengths not less than 12 feet, unless interrupted by fittings. D. Install ducts with fewest possible joints. E. Install fabricated fittings for changes in directions, changes in size and shape, and connections. F. Install couplings tight to duct wall surface with a minimum of projections into duct. G. Install ducts, unless otherwise indicated, vertically and horizontally, parallel and perpendicular to building lines; avoid diagonal runs. H. Install ducts close to walls, overhead construction, columns, and other structural and permanent enclosure elements of building. I. Install ducts with a clearance of 1 inch, plus allowance for insulation thickness. Page 11 of 14
J. Conceal ducts from view in finished spaces. Do not encase horizontal runs in solid partitions, unless specifically indicated. K. Coordinate layout with suspended ceiling, fire- and smoke-control dampers, lighting layouts, and similar finished work. L. Electrical Equipment Spaces: Route ductwork to avoid passing through transformer vaults and electrical equipment spaces and enclosures. M. Non-Fire-Rated Partition Penetrations: Where ducts pass through interior partitions and exterior walls, and are exposed to view, conceal space between construction opening and duct or duct insulation with sheet metal flanges of same metal thickness as duct. Overlap opening on four sides by at least 1-1/2 inches. N. Fire-Rated Partition Penetrations: Where ducts pass through interior partitions and exterior walls, install appropriately rated fire damper, sleeve, and firestopping sealant. Fire and smoke dampers are specified in Division 15 Section "Duct Accessories." Firestopping materials and installation methods are specified in Division 7 Section "Firestopping." 3.2 UNDERSLAB DUCT INSTALLATIONS A. Verify undamaged conditions of duct before enclosure with fill or encasement. B. Install underslab ducts according to SMACNA's "HVAC Duct Construction Standards-- Metal and Flexible" and as indicated. C. Protect ducts from damage by equipment used in placing concrete on or around ducts. D. Protect duct openings. 3.3 RANGE HOOD EXHAUST DUCT INSTALLATIONS A. Install ducts to allow for thermal expansion of ductwork through 2000 deg F temperature range. B. Install ducts without dips or traps that may collect residues, unless traps have continuous or automatic residue removal. C. Install access openings at each change in direction and at 50-foot intervals; locate on sides of duct a minimum of 1-1/2 inches from bottom; and fit with grease-tight covers of same material as duct. D. Do not penetrate fire-rated assemblies. 3.4 DISHWASHER EXHAUST DUCT INSTALLATIONS A. Install dishwasher exhaust ducts according to SMACNA's "HVAC Duct Construction Standards--Metal and Flexible." B. Dust work shall be aluminum or stainless steel. Page 12 of 14
3.5 SEAM AND JOINT SEALING A. General: Seal duct seams and joints according to Seal Class A, No Exceptions. As indicated and as described in SMACNA's "HVAC Duct Construction Standards--Metal and Flexible." B. Pressure Classification Less Than 2-Inch wg: Transverse joints. C. Seal externally insulated ducts before insulation installation. 3.6 HANGING AND SUPPORTING A. Install rigid round, rectangular, and flat-oval metal duct with support systems indicated in SMACNA's "HVAC Duct Construction Standards--Metal and Flexible." B. Support horizontal ducts within 24 inches of each elbow and within 48 inches of each branch intersection. C. Support vertical ducts at a maximum interval of 16 feet and at each floor. D. Install upper attachments to structures with an allowable load not exceeding one-fourth of failure (proof-test) load. E. Install concrete inserts before placing concrete. F. Install powder-actuated concrete fasteners after concrete is placed and completely cured. 3.7 CONNECTIONS A. Connect equipment with flexible connectors according to Section 15820 "Duct Accessories." B. For branch, outlet and inlet, and terminal unit connections, comply with SMACNA's "HVAC Duct Construction Standards--Metal and Flexible." 3.8 FIELD QUALITY CONTROL A. Disassemble, reassemble, and seal segments of systems as required to accommodate leakage testing and as required for compliance with test requirements. B. Conduct tests, in presence of Architect, at static pressures equal to maximum design pressure of system or section being tested. If pressure classifications are not indicated, test entire system at maximum system design pressure. Do not pressurize systems above maximum design operating pressure. Give seven days' advance notice for testing. C. Determine leakage from entire system or section of system by relating leakage to surface area of test section. D. Maximum Allowable Leakage: Comply with requirements for Leakage Classification 3 for round and flat-oval ducts, Leakage Classification 12 for rectangular ducts in pressure Page 13 of 14
classifications less than and equal to 2-inch wg (both positive and negative pressures), and Leakage Classification 6 for pressure classifications from 2- to 10-inch wg. E. Remake leaking joints and retest until leakage is less than maximum allowable. F. Nosing Strips shall be provided for all internally lined ductwork per SMACNA Standards regardless of air velocity.. Nosing strips shall be designed to prevent air-flow lifting of the insulation. F. Leakage Test: Perform tests according to SMACNA's "HVAC Air Duct Leakage Test Manual." Acceptable leakage rate is 3%, for +2 inch and +4inch W.G. duct. G. Leakage testing shall be in accordance with Section 15950 Testing/Balancing. 3.9 ADJUSTING A. Adjust volume-control dampers in ducts, outlets, and inlets to achieve design airflow. B. Refer to Section 15950 "Testing, Adjusting, and Balancing" for detailed procedures. 3.10 CLEANING A. After completing system installation, including outlet fittings and devices, inspect the system. Vacuum ducts before final acceptance to remove dust and debris. 3.11 SCHEDULES DUCTWORK MATERIAL SCHEDULE AIR SYSTEM Supply Return and Relief General Exhaust MATERIAL Galvanized Steel Galvanized Steel Galvanized Steel, Aluminum DUCTWORK PRESSURE CLASSIFICATIONS AIR SYSTEM Supply upstream of VAV box Supply downstream of VAV box Return General / Toilet Exhaust PRESSURE CLASSIFICATION + 4 inch w.g. + 2 inch w.g. - 2 inch w.g. - 1 inch w.g. 3.12 DUCT LEAKAGE TESTING PRESSURE CLASSIFICATION MAXIMUM LEAKAGE + 4 inch w.g. 3% + 2 inch w.g. 3% END OF SECTION Page 14 of 14