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 work.

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

Ductwork
1. Requirements:
• 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 as follows.
+ 10 m/sec (2,000 fpm): Main supply ducts.
+ 7.5 m/sec (1,500 fpm): Branch ducts and return/
exhaust systems.
+ 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 removal system.
3. Miscellaneous:
• 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 fans.
Capacity is 3 bathroom.
Where subducts are not allowed non-visible acces Ex aust Outlets:
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
and intakes.
• Where fireplaces are included, locate fireplace outlets 15 m (50 ft.) minimum from outside air intakes or operable windows.
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
waterproof joints.
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
systems.
• 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 drawings.
9. Back-Draft Dampers: Provide for exhaust fan discharge ducts.
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.