listed may result in objectionable air noise in the ducts.
Table 3 Recommended Maximum Duct Velocities, Feet Per Minute (FPM)
Main Ducts* Branch Ducts
Application
Supply Return Supply Return
Apartments 900 700 600 600
Auditoriums 1200 1000 1000 800
Banks 2000 1500 1600 1200
Hotel Rooms 1500 1300 1200 1000
Libraries 2000 1500 1600 1200
Meeting Rooms 2000 1500 1600 1200
Offices 2000 1500 1600 1200
Residences 900 700 600 600
Restaurants 2000 1500 1600 1200
Retail Stores 2000 1500 1600 1200
*When sound control is critical use branch duct velocities
Table 4 Duct Area Required at Listed Flow Conditions
CFM Area
Sq. In.
600FPM
Area
Sq. In.
800FPM
Area
Sq. In.
1000FPM
Area
Sq. In.
1200FPM
Area
Sq. In.
1600FPM
Area
Sq. In.
2000FPM
50 12
100 24 18 14 12
150 36 27 22 18 14
200 48 36 29 24 18 14
250 60 45 36 30 23 18
300 72 54 43 36 27 22
400 96 72 58 48 36 29
500 120 90 72 60 45 36
750 180 135 108 90 68 54
1000 240 180 144 120 90 72
1250 300 225 180 150 113 90
1500 360 270 216 180 135 108
1750 420 315 252 210 158 126
2000 480 360 288 240 180 144
Note: For Systems not over 100 feet equivalent length. Do not apply this table to duct systems
which exceed 100 equivalent feet in length. For longer systems refer to ACCA Manual D.
Incorrectly sized ducts can result in unsafe or uncomfortable operation.
Table 5 Round Duct Equivalent Area
Nominal Size 4 5 6 7 8 9 10 12
Area in.
2
12.5 19.6 28.3 38.5 50.3 63.6 78.5 113.1
8
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