|Hotels ,Motels ,Equipments, Sheet Metal
Ducts shall be constructed of galvanised iron unless specifically
noted otherwise. The recommendations of ASHRAE/SMACNA shall
be used as a guide for sizing, minimum gauges, bracing and
construction details. Fibreglass ducts, bearing the UL label
and constructed in accordance with SMACNA standards, may
be considered for use in low pressure systems. Duct work
exposed in B.O.T.H. areas shall be galvanised and not fibreglass.
Kitchen range hood duct work shall be constructed of black
iron with welded seams and liquid tight joints. The system
shall be designed in full compliance with NFPA 96 and the
applicable local codes having jurisdiction.
Branch duct work from moisture emitting equipment, e.g.,
dishwashers, pot sinks, etc., and indoor swimming pools,
shall be constructed of copper, stainless steel or aluminium,
with water tight joints, pitched back toward the equipment.
Electrolytic isolation shall be provided at connections
to iron duct work. Fire dampers shall be provided in branches
where connections are made to the Kitchen hood exhaust duct
Fire dampers shall be installed where required by NFPA
90A and the applicable local codes having jurisdiction and
must be shown on the drawings. A schedule of fire dampers
is to be provided as part of the maintenance manuals
• Type: Low and medium velocity galvanized sheet metal
constructed in compliance with SMACNA Standards. In no case
may fiberglass ductboard be used.
• Joints: Seal supply and return ductwork joints and
seams with hard-cast. • Runouts to Diffusers: May
be medium pressure rated,
externally insulated, spiral wound, flexible duct with a
maximum length of 2.4 m (8 ft.). • Sizing: To minimize
airborne noise and ensure space
noise criteria are met, size ductwork for maximum duct velocity
+ 10 m/sec (2,000 fpm): Main supply ducts.
+ 7.5 m/sec (1,500 fpm): Branch ducts and return/
+ 4 m/sec (800 fpm): Ducts serving room terminal air devices.
+ Duct Friction Loss: Not to exceed 0.10 inch w.c. per 30.5
m (100 ft.) of duct.
• Turning Vanes: Provide turning vanes in rectangular
elbows greater than 45 degrees.
2. Kitchen Hood Exhaust: Provide dedicated hood exhaust
duct system for each hood in the kitchen in a 2- hour fire-rated
enclosure with cleanout and sprinkler head access doors.
Provide dedicated hood exhaust duct system for the bakery.
• Type: 16 gage black steel ductwork, sloped back
to the hood, with welded drip-proof seams. Flanged and gasketed
joints are not allowed. Galvanized steel is not acceptable.
As an option, UL approved prefabricated and pre-insulated
systems are acceptable.
• Cleanouts / Access Doors: Locate at base of vertical
riser, at every change in direction, and at sprinkler heads.
Maximum spacing of 6 m (20 ft.) in horizontal; maximum spacing
of every third floor of vertical riser.
• Sizing: Based on velocity of 7.5 m/sec (1,500 fpm)
to 10 m/sec (2,000 fpm) to prevent grease from accumulating
in ducts and to ensure grease not trapped in hood filters
is exhausted away from building.
• Exhaust Fan: High velocity discharge at 13 m/sec
(2,500 fpm) with drain plug and removable stainless steel
drain pan. • Location: Roof mounted to disperse exhaust
away from < building and to prevent reentry of contaminated
air into outside air intakes. Position fan so that entire
kitchen exhaust system is under negative pressure.
• Dampers: Not acceptable in grease exhaust systems.
• Insulation: Provide 50 mm (2 inch) high temperature
fiberglass insulation with all-service jacket on entire
grease exhaust duct.
• Consider use of exhaust hoods with Ultraviolet grease
• Dedicated kitchen dishwasher exhaust and laundry
ironer exhaust is welded stainless steel duct sloped back
to equipment for drainage of condensation and ducted directly
to outside of building.
• Do not connect dishwasher exhaust to kitchen hood
exhaust system or to other building exhaust systems.
• Construct laundry dryer exhaust from galvanized
sheet metal with waterproof joints sloped back to equipment
for drainage of condensation and ducted to building exterior.
Fabricate indoor pool and po ductwork from stainless steel.
Design exhaust system of sewage ejector and grease trap
rooms for negative pressure with fans located at remote
end of the system and duct to building exterior.
Guestroom Toilet Exhaust: Provide sidewall mounted exhaust
registers sub-ducted into exhaust risers to roof mounted
Capacity is 3 bathroom.
Where subducts are not allowed non-visible acces Ex aust
Locate exhaust outlets no closer than 6 m
• Locate kitchen exhaust outlets no closer than 15
m (50 ft.) away from outside air intakes such that prevailing
winds carry vapors away from the building
• Where fireplaces are included, locate fireplace
outlets 15 m (50 ft.) minimum from outside air intakes or
6. Exterior Ductwork: Not recommended, but where necessary
provide as follows:
• 450 mm (18 inch) minimum above roof to permit servicing
of roof area.
• Steps over ductwork for access to roof areas and
roof mounted systems.
• With 25 mm (1 inch) minimum thickness, rigid phenolic
insulation and aluminum jacket with
7. Duct Insulation: Acoustic lining may not be used.
Provide 18 mm (¾ inch) minimum thickness, rigid phenolic
insulation on supply and outside air ductwork.
8. Fire Dampers:
• Provide fire dampers where required, to meet necessary
fire ratings of structural, wall and ceiling
• Provide 200 x 200 mm (8 x 8 inch), framed, hinged,
lockable access doors at fire dampers. Coordinate locations
with architectural features shown on reflected ceiling plan
9. Back-Draft Dampers: Provide for exhaust fan discharge
10. Balancing Devices:
• Balancing Dampers: Provide balancing dampers in
all supply and exhaust risers, and runouts to registers
/ diffusers. Where possible, locate balancing dampers in
ceiling space over back-of-house areas where remote servicing
can be accomplished out of public and guest view.
• Splitter Dampers: Avoid use of multiple splitter
dampers in individual duct systems.
• Volume Dampers: Provide in branch ducts at connection
to main duct.