15840-4
DUCTWORK AND DEVICES
a. Install ducts larger than 15 inches diameter and all square and
rectangular ducts passing through floors, walls, ceilings or roof through
prepared openings.
b. Provide one-inch clearance between the duct and the prepared opening,
or one-inch clearance between the insulation and the prepared opening
for insulated ducts, except at grilles, registers, and diffusers.
c. Space between the prepared opening and the duct or duct insulation shall
be packed with commercial grade twisted fireproof yarn. Seal the
annular space with polyurethane sealant, S-6, per Section 07900 for
standard penetrations. Penetrations through fire rated walls and floors
shall utilize Fyre-shield sealant, S-7, per Section 07900 in lieu of the
polyurethane sealant.
3. | The contractor shall be responsible for the proper size and location of sleeves
and prepared openings. The Drawings attempt to indicate approximate sleeve
and prepared opening sizes. The actual size is to be carefully coordinated with
concrete placement and other construction activities to ensure sufficient and
properly sized sleeves and prepared openings are provided. Due consideration
should be given to the need for increased opening sizes to accommodate
devices such as fire dampers or contractor selected equipment.
4. Provide duct sleeves and prepared openings for all duct mains and duct
branches. Branch takeoff connections to grilles, registers, and diffusers shall
be in accordance with SMACNA HVAC Duct Construction Standards - Metal
& Flexible 2nd Edition.
Duct Supports: Provide and install duct supports not less than two 1-inch by 1/16-
inch thick spaced one on each side of duct in accordance with SMACNA HVAC
Duct Construction Standards Metal & Flexible 2nd Edition. Supports on the risers
shall allow free vertical movement of the duct.
Support ducts and install to be completely free from vibration under all conditions
of operation. Attach supports only to structural framing member and concrete slabs.
Do not anchor supports to metal decking unless a means is provided and approved
for preventing the anchor from puncturing the metal decking. Where supports are
required between structural framing members, provide suitable intermediate metal
framing. Where C-clamps are used, use retainer clips.
Access Panels: Provide access panels for all concealed valves, controls, dampers,
duct access doors, and any item requiring inspection and maintenance. Provide
access panels of sufficient size.
Air Filters: Install air filters so that access space for servicing the filters is provided.
Install filters with suitable sealing to prevent bypassing of air.
Flexible Collars: Provide flexible collars in connections between fans and ducts or
casings and where ducts are of dissimilar metals, as shown on the Drawings and
were required. Make collars of neoprene coated glass fabric weighing
approximately 30 ounces per square yard. Securely fasten flexible connections by
stainless steel clinch type bands for round ducts. For rectangular ducts, install the
flexible connections locked to metal collars using normal duct construction
standards.
Flashings: Where ducts pass through exterior building walls and roofs, provide
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