SECTION 15815 Sheet Metal Duct Work Part 1 - General 1.1 Related Documents
SECTION 15815 Sheet Metal Duct Work Part 1 - General 1.1 Related Documents
SECTION 15815 Sheet Metal Duct Work Part 1 - General 1.1 Related Documents
PART 1 - GENERAL
A. The work includes the providing of all labor, supervision, materials, equipment,
accessories, services and tests necessary to complete, make ready, and set to work for
acceptance by the Owner, all sheet metal work in accordance with Drawings and
Specification.
C. Standards Compliance: Comply with the requirements of applicable local codes and
the standards outlined in section 15020.
1.4 SUBMITTALS
B. Manufacturer Certification.
PART 2 - PRODUCTS
A. All ductwork, sheet metal flues, register boxes, air changers, dampers and all auxiliary
work of any kind necessary to make the various air conditioning, ventilating and
heating systems of the building complete and ready for satisfactory operation shall be
furnished and installed. All ductwork shall be constructed in accordance with the
latest edition of SMACNA Duct Construction Standards.
B. All ductwork indicated on drawings is schematic. Ductwork shall be set up and down,
offset, change in duct size and/or location to meet field conditions and coordination
between trades without additional cost to the owner.
C. Dimensions given on drawings of all acoustically lined ducts shall be clear inside
dimension.
G. Access doors as specified elsewhere shall be provided in the ducts wherever required
for access to fusible link dampers, controls, and all equipment concealed inside the
ducts.
H. Unless otherwise noted, all ductwork shall be substantially built of lock forming
quality galvanized steel having a galvanized coating of 33 grams for both sides of 0.1
sq. m. of sheet. Ducts shall have approved joints and seams smooth on the inside with
a neat finish on the outside. Duct joints shall be as airtight as possible, with laps made
in the direction of air flow and no flanges projecting into the air stream. All angles
shall be galvanized.
I.Tapers for low pressure ducts shall be constructed in accordance with SMACNA standards.
When a taper is used in a "diverging" air flow and the duct size increases, the sides are
to be pitched to maximum of 20 degrees to prevent turbulence or an additional
C. Total air outlet volume for low pressure duct systems, measured by means of a
velometer, shall be at least 95% of actual fan supply (measured by means of duct
traverse taken with a pitot tube and water manometer.)
B. All medium pressure ductwork shall be galvanized steel except where otherwise
specified, with gauges, as follows, brace and construction so as to support its own
weight and not to break, rattle or deform under pressure.
C. Total air outlet volume for medium pressure duct systems, measured by means of a
velometer, shall be at least 98% of actual fan supply (measured by means of a duct
traverse taken with a Pitot tube and water manometer) i.e., maximum 2% leakage.
Ducts shall have welded seams and 50 mm x 50m x 6 mm matched angle iron joint
connections. All joints shall be ground smooth, fitted and welded to make
connections grease-proof and airtight. The exterior of all kitchen cooking
equipment ventilation ducts shall have welded 38 mm x 38 mm x 3 mm angles,
punched for securing block insulation. Provide 457 mm x 457 mm access doors on
side of horizontal duct at 4.5 m spacing. Access doors shall be same as duct gauge,
and shall be located not less than 50 mm above bottom of duct to provide a drip lip.
All horizontal ducts shall be pitched back to hoods 1mm per 30 mm or maximum
pitch attainable. Provide residue trap and cleanout provisions at base of each
vertical risers. Kitchen exhaust ducts shall contain no dampers, turning vanes or
obstructions.
C. Smoke breechings shall be hung from the structure. Hangers for supports shall be
not less than 19 mm diameter steel rods, spaced not more than 2.4 m apart. Steel
beams shall be inserted where required. Use 63 mm steel angles as stiffeners for
hangers at top and bottom side of breeching.
D. Each smoke breeching shall be equipped with hinged cleanout doors not less than
381 mm x 381 mm in size. One such cleanout door shall be provided at the end of
smoke breechings. When the horizontal run of smoke pipe exceeds 5 meters
additional cleanout doors shall be provided and shall be so spaced that the distance
between cleanout doors shall not exceed 5 meters. Unless otherwise specified or
approved, cleanout doors shall be installed in sides of smoke breechings.
A. All air casings and plenums shall be constructed of 1.5mm galvanized iron braced
and stiffened on outside by means of 50mm x 50mm x 6mm galvanized steel
angles, or with 15 mm standing seam panels not to exceed 660 mm width.
Standing seams are to have additional right angle bend and shall be capped with
No. 1.2 mm galvanized "U" cap over entire length of seam. All joints shall be
caulked to make them airtight. The bottom of all air chambers at the floor shall be
gasketed to prevent air leakage.
B. Casings shall be supported on floor curbs. The bottom of all air casings at the floor
and at any other connection to masonry shall be riveted to 38 mm x 38 mm x 3 mm
galvanized steel angles which have been secured to masonry with expansion shields
and caulked tight with cement.
D. This Contractor shall be responsible for any additional bracing required for
stiffness including roof deck of casings. The roof deck shall be braced and
supported from the structure, if required.
B. All access doors in sheet metal ducts shall be hung on heavy flat hinges and shall
be secured in the closed position by means of cast zinc clinching type
latches. Where space conditions preclude hinges, use four heavy window type
latches. Doors into ducts shall in general not be smaller than 300 x 300 except for
access door to fire dampers which will depend on size of fire damper.
D. Each sheet metal chamber shall have access doors for access to all parts of the
system. Doors shall be fitted with cast zinc door latches, two per door. Latches
shall be operable from both sides of casing. As per SMACNA Details Hinges shall
be extra heavy, zinc plated hinges, minimum of three per door. The doors shall be
felted or provided with rubber gaskets so as to make them airtight. The doors shall
be made with inner and outer sheets 50 mm apart so that they may be properly
insulated and properly operated. Doors shall be a minimum size of 500 mm x 1200
mm.
2.8 DAMPERS
A. Furnish and install all dampers required for all systems to accomplish the intent of the
drawings and specifications.
Dampers to be located at every branch has more than two outlets .
A. Furnish and install fusible link fire dynamic where shown on the drawings and in
accordance with applicable local regulations.
B. Dampers are required wherever ducts enter or leave shafts or pierce fire-rated
construction or concrete slab .
C. Fire dampers shall be constructed of 0.7 mm and sleeve 1.2 mm sheet steel, with
fusible links designed to break at 74C.
D. The space between the damper sleeve and the masonry opening shall be packed
with an approved sealant similar to Dow Corning "Fire Stop Foam and Sealant".
Firmly attach the fire damper frame or sleeve to the wall.
1. Type I (1 1/2 hr.); With factory standard sleeve in air stream for air
velocities up to 10 m/sec. 100% free area out of air stream for all ducts less
than 300 mm in height and air velocities greater than 10 m/sec.
2. Type II (3 hr.); With factory standard sleeve in air stream. For velocities up
to 10 M/sec. 100% free area out of air stream for all ducts less than 300
mm in height and velocities greater than 10 m/sec.
3. Spring loaded damper shall be provided for installation in vertical ducts and
shall be same as above.
F. Provide an access door in the duct on the same side as the fusible link to permit
ready access for inspection and maintenance.
G. All fire dampers must be provided with an external device which indicates the
position of the damper.
A. Furnish and install smoke dampers where shown on the drawings in accordance
with applicable local regulations. Fire/smoke damper system shall be subject to
approval of the local fire department.
B. In general, dampers are required to isolate air handling equipment from the
remainder of the system and wherever ducts penetrate smoke partitions. Where fire
partitions are used as smoke partitions, dampers shall be combination fire/smoke
type as specified above.
1. Type I; with factory standard sleeve and electric operator, models MA-418
or MP-2781 (220v/50 hz).
2. Type II; parallel blade damper with electric operator 220v/50hz. Use in
discharge ductwork at supply fan and return air where applicable.
F. Smoke dampers where indicated on the plans shall conform to the UL555S leakage
class specified . Damper actuator shall be UL listed and suitable for the
application . The operating ambient temperature of the
A. Examine the drawings, and in cooperation with the Electrical trade confirm the
final location of all electrical equipment to be installed in the vicinity of piping.
Plan and arrange all overhead piping no closer than 600 mm from a vertical line to
electric motors and controllers, switchboards, panel boards, or similar equipment.
B. Where the installation of piping does not comply with the requirements of
foregoing paragraph, where feasible, the piping shall be relocated.
1. Provide and erect a gutter of 1 mm cold rolled copper under every pipe
which is within 600 mm of being vertically over any motor, electrical
controllers, switchboards, or the like.
2. Each gutter shall be soldered and made watertight, properly suspended and
carefully pitched to a convenient point for draining. Provide a 75 mm drain
to nearest floor drain or slop sink, as approved.
D. Each coil section composing the coil bank of a built up rig shall have an individual
drain pan extending 300 mm past the front edge of the coil with a minimum 50 mm
vertical lip downstream of the coil. The top edge of the lip shall be turned
backward. The pans shall be connected with galvanized pipe to permit drainage to
the floor drain. Pans shall be minimum 1.7 mm galvanized iron and shall be
pitched to the drain.
A. All fan and air supply unit connections, both at inlet and discharge shall be made
with an approved flame proof fabric, so as to prohibit the transfer of vibration from
fans to ductwork connecting thereto, without air leakage. The materials between
the clamps shall have sufficient slack so as to prevent tearing due to fan movement.
B. The flexible connections shall be a minimum of 200 mm total length and held in
place with flanged connections or heavy metal bands securely attached, to prevent
any leakage at the connection points.
A. Where indicated, provide aluminum sheet complying with ASTM B 209, Alloy
3003.
A. For all exposed uninsulated connections to kitchen equipment and where indicated
on the drawings, provide stainless steel ducts; Type 304, with polished finish where
exposed to view in occupied spaces, mill finish elsewhere. Protect finished
surfaces with mill-applied adhesive protective paper, maintained through
fabrication and installation.
D. Where used for moisture laden air, pitch duct to convenient point to allow for
drainage. Provide 24mm plastic drain pipe and run to nearest drain, or as
approved.
This item could be used in lieu of the normal sheet metal duct work as alternative to reduce
duration in the time schedule
Furnish and install pre –insulated ductwork ducts hanger and all necessary accessories for
proper installation of damper , fire damper. diffusers and grilles … etc.
Ducts surface area , for payment purpose , is be based on the actual dimensions of ducts
installed . Rates should be calculated into consideration waste , joints , seams , etc.
Technical Specifications :
Insulation
component : Water formulated polyurethane foam without use 0 CFC or
HCFC ,density of 46 – 50 kg /m3 ;
Thickness : 20 mm.
Outdoor Ducts
In all sections installed outside , the ducts must be built using sandwich type
PIRAL HD HYDROTEC OUTSIDER panels with the following
characteristics :
Conductivity : 0.024 W ( M o C ) at 10 o C ;
Thickness : 30 mm.
And will also be protected with water proofing resin ( GUM SKIN
type ) .
Bitumen – based compounds must not be used .
The ducts will be constructed according the type standards type standards.
Wherever necessary , the ducts must be provided with the appropriate
reinforcements to guarantee sufficient mechanical seal against a maximum
internal pressure of 500 pa during operation .
Elbows and special pieces will be provided with turning vanes wherever indi-
cated .
Whenever the ducts penetrate the building’s roof , they will be provided with “
gooseneck “ elbows at the ends in order to prevent the entry of snow and water .
Ducts Sealant .
All ducts joints dampers and antivibration should be sealed with non–toxic , UV
radiation and soluble salts resisting gasket .
The joints between one ducts and the next will be performed using the special “
invisible “ flanges with unexposed bayonet coupling and ensure the appropriate
pneumatic and mechanical seal .
Bayonet should be made of shock – resistant polymer and has to be self – lubri-
cating for easy insertion in flange with perfect air tightness .
The flange ends should be provided with covering angle to prevent bayonet
from getting out and to achieve a good aesthetic finish ,
The ducts will be supported by the appropriate supports at intervals of no more than 4
m whenever the greater of the ducts is less than 1 m , and intervals of no more than 2
m whenever the greater side of the ducts is more than 1 m .
Ducts positioned outside will be bracketed every 2 m and raised from ground using
the appropriate wind braces . Whenever positioned horizontally , they must be in-
Accessories such as volume dampers , fire barriers , and ducts coils , and so on , will
be provided with independent support in such a way that their weight does not bear on
the ducts .
All the openings of the ducts facing outside ( external air inlet , internal air expulsion ,
and so on ) will be equipped with the appropriate screens to prevent the entry of brads
.
Wherever indicated , the ducts will also be provided with the appropriate test points
for the velocity sensors and inspection doors for cleaning and inspection all along the
route .
The inspection doors can be built using same sandwich panels used for the ducts in
combination with the appropriate section bars , and will be equipped with liners that
ensure sufficient pneumatic seal .
The connections between the air handling units and the ducts will be made using the
appropriate vibration damping joints in order to reduce all vibrations .The ducts will
be provided with independent support in drier to prevent the weight of the ducts from
being transferred to the flexible couplings . The connection to the air handling unit
will also permit easy uncoupling for normal system maintenance . Whenever the vi-
bration damping joints positioned outside , they will be rendered waterproof .
PART 3 - EXECUTION
3.1 INSTALLATION
A. Install ductwork in accordance with approved shop drawings and conditions at the
site. Advise Architect in writing of any condition which prevents the approved
duct installation.
C. Provide 25 mm test ports with standard weight piping caps at all ideal locations for
obtaining air. test readings, static pressure, duct traverses temperature etc.
1. Do not put screws, etc. on the inside of any sheet metal duct. Lint will
"snowball" if caught by any protrusion.
2. Do not connect dryer vent duct to the filter until electric and compressed air
installations are completed.