TT
Series
LR
Manual
Page
12
DUCT
TRAVERSE
POINTS
Principle
of
Operation:
Pitot
Head
Velocity
Pressure*
=
Total
Pressure
–
Static
Pressure
*
Calculated
by
the
Micromanometer
The
nose
of
the
Pitot
Tube
should
face
directly
into
the
airstream
thus
the
Total
Pressure
flows
down
the
inner
tube
which
is
connected
to
the
Signal
In
port.
The
static
holes
are
positioned
around
the
side
of
the
Pitot
Tube
and
lead
into
an
outer
tube.
This
is
connected
to
the
black
tubing
which
in
turn
is
connected
to
the
Reference
port.
Log
Linear
Rule
for
Traverse
Points
on
3
Diameters
in
a
Circular
Duct:
Ideally traverse
points should
be
at
least
six
duct
diameters
away
from
any
bend
or
obstruction
in
the
system.
The
Pitot
Tube
should
be
inserted
at
right
angles
to
the
walls
of
the
ducts
and
measurements
are
taken
in
the
positions
shown
in
the
diagrams
(left).
The
directional
pointer
can
be
used
to
ensure
that
the
Pitot
Tube
head
is
parallel
to
the
duct
walls.
Alternative
Measuring
Points
and
Traverse
Lines
Relative
to
Side
Lengths
for
Regular
Ducts:
0.061D
0.235D
0.563D
0.437D
0.765D
0.939D
0.
07
4D
0.
28
8D
0.
5D
0.
71
2D
0.
92
6D
0.032D
0.135D
0.321D
0.679D
0.865D
0.968D
D
TP
SP
