52
—
S
HEET
M
ETAL
/HVAC
P
RO
C
ALC
(Cont’d)
KEYSTROKE
DISPLAY
4. Calculate Centerline Radius, Wrapper Length, Heel Radius,
Throat Radius and Theta:
Ç (
RAD 77-7/16
INCH
(
WL 84-5/8
INCH
(
HEEL 111-7/16
INCH
(
THRT 43-7/16
INCH
(
THET 15.6571°
5. Convert Theta to degrees:minutes:seconds:*
Ç •
6. Multiply by two to double offset:**
x 2 =
DMS
15.39.2
5
DMS
31.18.51
*The
angle
of
Theta
can
be
used
to
divide
the
offset
into
degreed
elbows
for
more
manageable
sections.
If
the
angle
calculated
is
used,
there
would
be
four
(4)
elbows
each
at
15°39’2
5
”.
**If
two
(2)
elbows
were
desired,
the
calculated
angle
can
be
doubled
(each
elbow
would
be
31°18’51”).
Doubling
Theta
provides
the
maximum
elbow
size
for
this
offset
and
radius
combination.
The
total
angle
on
either
side
of
center
can
be
divided
into
as
many
elbows
as
is
required
to
make
the
offset
manageable.
In
the
case
above,
the
maximum
angle
that
can
be
divided
is
31°18’51”.
