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    SECTION 15890

    DUCTWORK

   PART 1 - GENERAL

   1.01 WORK INCLUDED

    A. Low pressure ducts.

    B. Casings.

    C. Fiberglass reinforced plastic ductwork.

    D. Buried ducts.

    E. Duct cleaning.

   1.02 RELATED WORK

    A. Section 09900 - Painting: Weld priming, weather resistant, paint or coating.

    B. Section 15140 - Supports and Anchors: Sleeves.

    C. Section 15260 - Piping and Duct Insulation.

    D. Section 15910 - Ductwork Accessories.

    E. Section 15940 - Air inlets and Outlets.

    F. Section 15990 - Testing, Adjusting and Balancing.

   1.03 REFERENCES

    A. ASHRAE - Handbook 1981 Fundamentals; Chapter 33 - Duct Design.

    B. ASHRAE - Handbook 1983 Equipment; Chapter 1 - Duct Construction.

    C. ASTM A 167 - Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip.

    D. ASTM A 525 - General Requirements for Steel Sheet, Zinc- Coated (Galvanized) by the Hot-Dip Process.

    E. ASTM A 527 - Steel Sheet, Zinc-Coated (Galvanized) by Hot- Dip Process, Lock Forming Quality.

    F. NFPA 90A - Installation of Air Conditioning and Ventilating Systems.

    G. SMACNA - Low Pressure Duct Construction Standards.

   1.04 DEFINITIONS

    A. Duct Sizes: Inside clear dimensions.

    B. Low Pressure: Three pressure classifications: 1/2 inch WG (125 Pa) positive or negative static pressure and velocities less than 2,000 fpm (10 m/sec); 1 inch WG (250 Pa) positive or negative static pressure and velocities less than 2,500 fpm (12.7 m/sec) and 2 inch WG (500 Pa) positive or negative static pressure and velocities less than 2,500 fpm (12.7 m/sec).

   1.05 REGULATORY REQUIREMENTS

    A. Construct ductwork to NFPA 90A.

   1.06 SUBMITTALS

    A. Submit shop drawings and product data under provisions of Section 01300.

    B. Indicate duct fittings, particulars such as gages, sizes, welds, and configuration prior to start of work for low pressure glass fiber duct, and ductile iron pipe systems.

    C. Submit samples under provisions of Section 01300.

    D. Submit manufacturer's installation instructions for glass fiber ducts under provisions of Section 01300.

   1.07 DELIVERY, STORAGE, AND HANDLING

    A. Deliver products to site under provisions of Section 01600.

    B. Store and protect products under provisions of Section 01600.

   PART 2 - PRODUCTS

   2.01 MATERIALS

    A. General: Non-combustible or conforming to requirements for Class 1 air duct materials, or UL 181.

    B. Steel Ducts: Stainless steel sheet, lock-forming quality in conformance with ASTM A90.

    C. Stainless Steel (SST) Ducts: ASTM A167, Type 304.

    D. Fiberglass Reinforced (FRP) Plastic Ducts: Resin conforming to ASTM C581-68, flanged field joints, flamespread of 25 or less.

    E. Fasteners: Rivets, bolts, or stainless sheet metal screws.

    F. Sealant: Non-hardening, water resistant, fire resistive, compatible with mating materials; liquid used alone or with tape, or heavy mastic.

    G. Hanger Rod: Stainless steel, threaded both ends, threaded one end, or continuously threaded.

    H. Solder: ASTM B32 Grade 50B.

   2.02 LOW PRESSURE DUCTWORK

    A. Fabricate and support in accordance with SMACNA Low Pressure Duct Construction Standards and ASHRAE handbooks, except as indicated. Provide duct material, gages, reinforcing, and sealing for operating pressures indicated.

    B. Size round ducts installed in place of rectangular ducts in accordance with ASHRAE table of equivalent rectangular and round ducts. No variation of duct configuration or sizes permitted except by written permission.

    C. Construct T's, bends, and elbows with radius of not less than 1-1/2 times width of duct on centerline. Where not possible and where rectangular elbows are used, provide turning vanes.

    D. Increase duct sizes gradually, not exceeding 15 degrees divergence wherever possible. Divergence upstream of equipment shall not exceed 30 degrees; convergence downstream shall not exceed 45 degrees.

    E. Provide easements where low pressure ductwork conflicts with piping and structure. Where easements exceed 10 percent duct area, split into two ducts maintaining original duct area.

    F. Connect flexible ducts to metal ducts with adhesive plus stainless sheet metal screws.

    G. Use double nuts and lock washers on threaded rod supports.

   2.03 FIBERGLASS (FRP) DUCT

    A. All ductwork shall be hand laid fiberglass and shall be constructed per the National Bureau Standards PS 1569.

    B. Corrosion barrier shall be a minimum of 0.125" thick. The corrosion barrier shall not be included as a portion of the structural wall thickness.

    C. The minimum wall thickness shall be 0.250" thick.

    D. Duct shall be constructed of a reinforced polyester suitable for sewer gases and exposure to the atmosphere.

    E. Duct shall be joined by method of flanged connections.

    F. Provide a companion flange for connection to each fan. Coordinate with fan manufacturer for bolting pattern.

   PART 3 - EXECUTION

   3.01 INSTALLATION

    A. Obtain manufacturer's inspection and acceptance of fabrication and installation of fiberglass reinforced plastic ductwork at beginning of installation.

    B. Locate ducts with sufficient space around equipment to allow normal operating and maintenance activities.

    C. The general locations and run of ductwork are indicated. Where construction exigencies require a minor offset to clear an obstruction, perform such works without cost to the owner. Do not change sizes or make more than a minor change (two 45 degree elbows) without approval.

    D. Slope underground ducts to plenums or low pump out points at l:500. Provide access doors for inspection.

    E. During construction provide temporary closures of metal or taped polyethylene on open ductwork to prevent construction dust from entering ductwork system.

   3.02 DUCTWORK APPLICATION SCHEDULE

   AIR SYSTEM MATERIAL

   Low Pressure Supply, Stainless Steel or

   Intake and Exhaust Fiberglass Reinforced Plastic

   3.03 ADJUSTING AND CLEANING

    A. Clean duct system and force air at high velocity through duct to remove accumulated dust. To obtain sufficient air, clean half the system at a time. Protect equipment which may be harmed by excessive dirt with temporary filters, or bypass during cleaning.

    END OF SECTION