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B. MEDIUM VELOCITY DUCTWORK: Only 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 2,500 feet per minute and 0.25 inch of water gage per 100
equivalent feet to 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 4.0
feet of water per 100 equivalent feet of piping.
The corresponding
velocity limitations are:
4.0 Feet Per Second: Occupied Areas
8.0 Feet Per Second: Mains and Large Branches
C. For open systems, the recommended maximum friction loss shall be 4.0
feet of water per 100 equivalent feet of piping. The corresponding
velocity shall be 10 feet per second (maximum).
D. The minimum pipe size shall be 3/4". The size shall be reduced, as
required, only at the equipment connections.
3. HVAC SYSTEMS
3.1 GENERAL
The HVAC systems selection shall be on the life cycle cost analysis
and the system(s) with the lowest owning and operating costs shall be
selected as the basic of design.
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
evaluated from the life cycle cost analysis.
The corresponding
velocity limitations are:
4.0 Feet Per Second: Occupied Areas
8.0 Feet Per Second: Mains and Large Branches
3.2 ALL AIR SYSTEMS
A. SYSTEM FEATURES: The features listed below shall be incorporated in
design unless specific deviations recommended by a designer are
deemed beneficial for this project.
1. An all air system shall comprise of a single duct, horizontal,
draw-thru, chilled water (or direct expansion-DX), variable air
volume (VAV) air handling unit complete with fan, filter, and coil
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