06-06
velocity and static pressure drop shall be limited to 7.6 m/s (1,500
fpm) and 25 Pa (0.1 Inch Water Gage (WG) per 30 m (100 equivalent
feet) of duct length, respectively. The supply air ductwork between
the fan discharge and the inlet of the air terminal units shall be
low velocity design unless the space conditions do not permit so.
B. MEDIUM VELOCITY DUCTWORK: The supply air ductwork between the fan
discharge and inlet to the air terminal units can be medium velocity
type. Medium velocity ductwork shall be used only if the available
space conditions can not accommodate low velocity duct sizes. The
maximum velocity and the static pressure drop shall be limited to 13
m/s (2,500 fpm) and 63 Pa (0.25 In. WG.) per 30 m (100 equivalent
feet) of duct length, respectively.
2.11 PIPE SIZING CRITERIA
A. Pipe sizing shall be based on "Cameron Hydraulic Data"; with C=100
for open systems (Example: Cooling Tower) and C=150 for closed
systems (Example: Chilled and Hot Water Systems).
B. For closed systems, the limited maximum pressure drop shall be 1200
mm (4.0 feet of water) per 30 m (100 feet) equivalent length of
piping. The corresponding velocity limitations are:
1200 mm (4.0 Feet) Per Second: Occupied Areas
2400 mm (8.0 Feet) Per Second: Mains and Large Branches
C. For open systems, the limiting maximum pressure drop shall be 1200 mm
(4.0 feet) of water per 30 m (100 feet) equivalent length of piping.
The corresponding velocity shall be 3000 mm (10 feet) per second
(maximum).
D. The minimum pipe shall be 20 mm (3/4"). The size shall be reduced, as
required, only at the equipment connections.
3. HVAC SYSTEMS
3.1 GENERAL
The selection of the HVAC systems shall be based on the life cycle
cost analysis. For existing buildings, if the available space above
the suspended ceiling is restricted due to limited floor to floor
height, a central all air system can be eliminated from the life cycle
cost analysis and commercial grade, factory assembled, packaged,
direct expansion (DX) (or chilled water) systems can be considered for
evaluation. Examples of such systems are listed in Article 5, COOLING
SYSTEMS. In this section, the design criteria for an all air system
(with or without perimeter heating) and terminal cooling/heating
systems are listed.
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