06-06
The adjusted supply air volume shall be, thus, 10% in excess of
the calculated supply air volume.
3. Air Leakage: The leakage of the air through the supply air
distribution ductwork shall be computed on the basis of the
method described in the SMACNA Air Duct Leakage Test Manual.
The maximum leakage amount shall not exceed 4% of the adjusted
supply air volume.
4. Supply Fan Air Volume: The capacity of the supply air fan shall
be established per the following example:
Example:
a. Calculated Supply Air Volume
= 560 m3/min (20,000 CFM)
(Item 1)
b. Safety Margin
+ 56 m3/min ( 2,000
FM)
(Item 2) @ 10%
c. Adjusted Supply Air Volume
= 616 m3/min (22,000 CFM)
(Item 2)
d. Duct Air Leakage @4%
+ 5 m3/min (
880 CFM)
(Item 3)
e. Supply Fan Air Volume
= 640 m3/min (22,880 CFM)
(Item 4)
5. Equipment Selection: The capacities of the supply air fan,
together with the associated air handling unit components, that
is, cooling coil, preheat coil, energy recovery coil (if any),
filters, louvers, dampers, etc., shall be based and scheduled
on the supply fan air volume, that is, 640 m3/min (22,880 CMF).
A psychrometric chart shall be prepared for each air handling
unit and the heat gain due to the fan motor and duct friction
losses shall be clearly shown and accounted for while
calculating the cooling capacity of each unit.
6. Air Distribution:
a. The main supply air ductwork shall be sized to deliver the
supply fan air volume, that is, 640 m3/min (22,880 CFM) per
example outlined above.
b. The individual room air distribution system comprising of
supply, return, and exhaust air ductwork together with the
air terminal unit, reheat coil, and air outlets/inlets shall
be sized and selected on the basis of the adjusted supply
air volume, that is, 640 m3/min (22,000 CFM).
c. The fan and motor selection shall be based on the supply fan
air volume and static pressure adjusted, as necessary, for
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