104 Print Reading for HVACR
Copyright Goodheart-Willcox Co., Inc.
5.3.6 Elbows
Elbows are duct fi ttings that are connected between two sections of duct-
work to facilitate a change in the direction of airfl ow. Elbows are com-
monly 90° or 45° fi ttings but can be created at any angle based on job
specifi cations. Elbows can be fabricated either with or without turning
vanes, as specifi ed by the project plans.
Common elbows, Figure 5-35, include the following:
■ 8-D fi tting. A common elbow. Often, a 90° version and a 45°
version are used. This fi tting is popular because it is easy to fabricate
and less expensive than other styles.
■ 8-E fi tting. Turning vanes can be added to improve fi tting
performance.
■ 8-B fi tting. Another common elbow, which is a radius elbow.
■ 8-F fi tting. Like square elbow fi ttings, turning vanes can be added to
improve fi tting performance.
Consider the elevation view of the duct section shown in Figure 5-36.
Notice that this duct run has dashed lines and is using an 8-B 90° elbow
to redirect the duct run to a vertical orientation. The airfl ow is also
directed from left to right, and then upward after the 90° turn is made. It
cannot be determined whether the duct is a supply duct or a return duct.
If we examine the plan view of the same duct run, more information can
be obtained.
Recall that supply ducts are identifi ed by crossing diagonal lines, so
from the plan view, Figure 5-37A, we can see that this drawing represents
a portion of the supply duct system. Because these crossing diagonal lines
are solid, the duct is directed upward. Also, the acoustical lining in the
vertical portion of the duct run is visible and is therefore drawn with
solid lines. If the crossing diagonal lines were dashed, this means the duct
is being directed downward, Figure 5-37B.
If the portion of the system was a part of the return air ductwork,
the crossing diagonal lines would be replaced by a single diagonal line,
Figure 5-38. The upturning return ducts show airfl ow direction from left
to right and from right to left, while the downturning return ducts show
airfl ow direction from left to right and from right to left.
If the duct run were part of an exhaust system, the sections would appear
as in Figure 5-39. If the duct had been round instead of rectangular, the plan
view would have looked similar to that shown in Figure 5-40.
90° 45°
8-E
8-B
8-F
8-D
Goodheart-Willcox Publisher
Figure 5-35. Samples of elbow fi ttings.
10 x 20
8-B
Goodheart-Willcox Publisher
Figure 5-36. Elevation view of a duct
section of an air distribution system.
B
8-B
A
8-B
Goodheart-Willcox Publisher
Figure 5-37. A—Plan view of an upturning section of supply ductwork. B—Plan view of
a downturning section of supply ductwork.
10
x
20
20
x
10
20
x
10
Copyright Goodheart-Willcox Co., Inc.
5.3.6 Elbows
Elbows are duct fi ttings that are connected between two sections of duct-
work to facilitate a change in the direction of airfl ow. Elbows are com-
monly 90° or 45° fi ttings but can be created at any angle based on job
specifi cations. Elbows can be fabricated either with or without turning
vanes, as specifi ed by the project plans.
Common elbows, Figure 5-35, include the following:
■ 8-D fi tting. A common elbow. Often, a 90° version and a 45°
version are used. This fi tting is popular because it is easy to fabricate
and less expensive than other styles.
■ 8-E fi tting. Turning vanes can be added to improve fi tting
performance.
■ 8-B fi tting. Another common elbow, which is a radius elbow.
■ 8-F fi tting. Like square elbow fi ttings, turning vanes can be added to
improve fi tting performance.
Consider the elevation view of the duct section shown in Figure 5-36.
Notice that this duct run has dashed lines and is using an 8-B 90° elbow
to redirect the duct run to a vertical orientation. The airfl ow is also
directed from left to right, and then upward after the 90° turn is made. It
cannot be determined whether the duct is a supply duct or a return duct.
If we examine the plan view of the same duct run, more information can
be obtained.
Recall that supply ducts are identifi ed by crossing diagonal lines, so
from the plan view, Figure 5-37A, we can see that this drawing represents
a portion of the supply duct system. Because these crossing diagonal lines
are solid, the duct is directed upward. Also, the acoustical lining in the
vertical portion of the duct run is visible and is therefore drawn with
solid lines. If the crossing diagonal lines were dashed, this means the duct
is being directed downward, Figure 5-37B.
If the portion of the system was a part of the return air ductwork,
the crossing diagonal lines would be replaced by a single diagonal line,
Figure 5-38. The upturning return ducts show airfl ow direction from left
to right and from right to left, while the downturning return ducts show
airfl ow direction from left to right and from right to left.
If the duct run were part of an exhaust system, the sections would appear
as in Figure 5-39. If the duct had been round instead of rectangular, the plan
view would have looked similar to that shown in Figure 5-40.
90° 45°
8-E
8-B
8-F
8-D
Goodheart-Willcox Publisher
Figure 5-35. Samples of elbow fi ttings.
10 x 20
8-B
Goodheart-Willcox Publisher
Figure 5-36. Elevation view of a duct
section of an air distribution system.
B
8-B
A
8-B
Goodheart-Willcox Publisher
Figure 5-37. A—Plan view of an upturning section of supply ductwork. B—Plan view of
a downturning section of supply ductwork.
10
x
20
20
x
10
20
x
10