as specified in Section [03300A CAST-IN-PLACE STRUCTURAL CONCRETE] [03300N
CAST-IN-PLACE CONCRETE].
3.1.3
Access Panels
Install access panels for concealed valves, vents, controls, dampers, and
items requiring inspection or maintenance. Access panels shall be of
sufficient size and located so that the concealed items may be serviced and
maintained or completely removed and replaced. Access panels shall be as
specified in Section [05500A MISCELLANEOUS METAL] [05500N METAL
FABRICATIONS].
3.1.4
Flexible Duct
Install pre-insulated flexible duct in accordance with the latest printed
instructions of the manufacturer to ensure a vapor tight joint. Hangers,
when required to suspend the duct, shall be of the type recommended by the
duct manufacturer and shall be provided at the intervals recommended.
3.1.5
Metal Ductwork
Installation shall be according to SMACNA HVAC Duct Const Stds unless
otherwise indicated. Duct supports for sheet metal ductwork shall be
according to SMACNA HVAC Duct Const Stds, unless otherwise specified.
Friction beam clamps indicated in SMACNA HVAC Duct Const Stds shall not be
used. Risers on high velocity ducts shall be anchored in the center of the
vertical run to allow ends of riser to move due to thermal expansion.
Supports on the risers shall allow free vertical movement of the duct.
Supports shall be attached only to structural framing members and concrete
slabs. Supports shall not be anchored 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,
suitable intermediate metal framing shall be provided. Where C-clamps are
used, retainer clips shall be provided.
3.1.5.1
Underground Ductwork
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NOTE: Due to potential contaminants of air-stream,
such as pesticides and corrosion, underground
ductwork should be used only for exhaust air.
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Underground ductwork shall be PVC plastisol coated galvanized steel with
coating on interior and exterior surfaces and watertight joints. Ductwork
shall be installed as indicated, according to ACCA Manual 4 and
manufacturer's instructions. Maximum burial depth shall be 2 m 6 feet.
3.1.5.2
Radon Exhaust Ductwork
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NOTE: Subslab ventilation for radon mitigation will
be designed as prescribed in TM 5-810-1.
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Subslab suction piping shall be perforated where indicated.
PVC joints
shall be installed as specified in ASTM D 2855.
SECTION 15895
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