Chapter 5 Basic Duct Symbols and Drawings 95
Copyright Goodheart-Willcox Co., Inc.
Another way to reduce turbulence is to create rounded fi ttings. Although
rounded fi ttings, Figure 5-16, are more expensive to fabricate, they help direct
air through the fi tting more smoothly than rectangular-shaped fi ttings:
■ 1-K fi tting. A rounded outer edge with
a mitered inside corner.
■ 1-L fi tting. A radius elbow fi tting
that has both rounded outer and
inner edges. This fi tting has better
airfl ow than the 1-K fi tting.
■ 1-M fi tting. Obtained by adding
turning vanes to the 1-L fi tting. This
is the best of the three with respect
to airfl ow and the most expensive to
fabricate.
Upon initial inspection, these three
fi ttings might appear to be identical, but
there are important differences that will
affect the operation of the air distribution
system. Pay close attention to the notes
and references included in duct drawings.
Ignoring or misinterpreting the informa-
tion can lead to installation and opera-
tional problems later in the project.
Tee Fittings
In some cases, the supply air must immedi-
ately be directed in two different directions.
When such is the case, tee fi ttings are often
used, Figure 5-17. The most common tee is
the 1-O bullhead tee, which has no turning
vanes. A 1-P vaned tee is more desirable in
most applications.
Mitered inside corner
Air handler
Supply air
Radius elbow with turning vanes
Air handler
Supply air
1-K
Radius elbow
Air handler
Supply air
1-L 1-M
Rounded supply elbows
Goodheart-Willcox Publisher
Figure 5-16. Rounded supply elbows at the air handler.
Air handler
Supply
air
1-O
Air handler
Supply
air
Supply
air
Supply
air
1-P
Supply tees
Bullhead tee with turning vanes
Bullhead tee without turning vanes
Goodheart-Willcox Publisher
Figure 5-17. Supply tees at the air handler.
Copyright Goodheart-Willcox Co., Inc.
Another way to reduce turbulence is to create rounded fi ttings. Although
rounded fi ttings, Figure 5-16, are more expensive to fabricate, they help direct
air through the fi tting more smoothly than rectangular-shaped fi ttings:
■ 1-K fi tting. A rounded outer edge with
a mitered inside corner.
■ 1-L fi tting. A radius elbow fi tting
that has both rounded outer and
inner edges. This fi tting has better
airfl ow than the 1-K fi tting.
■ 1-M fi tting. Obtained by adding
turning vanes to the 1-L fi tting. This
is the best of the three with respect
to airfl ow and the most expensive to
fabricate.
Upon initial inspection, these three
fi ttings might appear to be identical, but
there are important differences that will
affect the operation of the air distribution
system. Pay close attention to the notes
and references included in duct drawings.
Ignoring or misinterpreting the informa-
tion can lead to installation and opera-
tional problems later in the project.
Tee Fittings
In some cases, the supply air must immedi-
ately be directed in two different directions.
When such is the case, tee fi ttings are often
used, Figure 5-17. The most common tee is
the 1-O bullhead tee, which has no turning
vanes. A 1-P vaned tee is more desirable in
most applications.
Mitered inside corner
Air handler
Supply air
Radius elbow with turning vanes
Air handler
Supply air
1-K
Radius elbow
Air handler
Supply air
1-L 1-M
Rounded supply elbows
Goodheart-Willcox Publisher
Figure 5-16. Rounded supply elbows at the air handler.
Air handler
Supply
air
1-O
Air handler
Supply
air
Supply
air
Supply
air
1-P
Supply tees
Bullhead tee with turning vanes
Bullhead tee without turning vanes
Goodheart-Willcox Publisher
Figure 5-17. Supply tees at the air handler.