Equivalent number
Duct pieces
length x used
3-1/ 4" x 10"
1 Ft.
Rect.,
straight
6" Round,
1 Ft.
straight
7"-10" Round,
1 Ft.
straight
3-1/ 4" x 10"
15 Ft.
Rect.90
0
elbow
3-1/ 4" x 10"
9 Ft.
Rect.45
0
elbow
3-1/ 4" x 10"
24 Ft.
Rect.90
0
flat elbow
3-1/ 4" x 10"
30 Ft.
Rect.
wall cap
with damper
3-1/ 4" x 10"
5 Ft.
Rect.to
6" round
transition
3-1/ 4" x 10"
20 Ft.
Rect.to
6" round
transition
90
0
elbow
6" Round,
15 Ft.
90
0
elbow
6" Round,
9 Ft.
45
0
elbow
Subtotal column 1 =
Maximum Duct Length: For satisfactory air movement,
the total duct length should not exceed 100 equivalent feet.
Duct pieces
=
T otal
Ft.
x (
) =
x (
) =
Ft.
x (
) =
Ft.
x (
) =
Ft.
x (
) =
Ft.
Ft.
x (
) =
Ft.
x (
) =
Ft.
x (
) =
Ft.
x (
) =
x (
) =
Ft.
x (
) =
Ft.
Ft.
5
Equivalent number
length x used
=
6" Round
30 Ft.
x (
) =
wall cap
with damper
6" Round,
30 Ft.
x (
) =
roof cap
6" round to
1 Ft.
x (
) =
3-1/ 4" x 10"
rect.
transition
6" round to
16 Ft.
x (
) =
3-1/ 4" x 10"
rect.
transition
90
elbow
0
7" - 10"
15 Ft.
x (
) =
Round,
90
0
elbow
7" - 10"
9 Ft.
x (
) =
Round,
0
45
elbow
7" - 10"
30 Ft.
x (
) =
Round
wall cap
with damper
7" - 10"
30 Ft.
x (
) =
Round,
roof cap
7" round to
8 Ft.
x (
) =
3 1/ 4" x 10"
rect.
transition
7" round to
23 Ft.
x (
) =
3-1/ 4" x 10"
rect.
transition
90
0
elbow
Subtotal column 2 =
Subtotal column 1 =
Total ductwork
=
T otal
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.