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TACHOMETER:
An
instrument
that
measures
the
speed
of
rotation,
usually
in
RPM.
TAPE
SAMPLER:
A
device
used
in
the
measure
of
both
gases
and
particulates.
It
allows
air
sampling
to
be
made
automatically
at
predetermined
times.
TEFC
(Totally
Enclosed,
Fan
Cooled):
Totally
enclosed
motors
equipped
with
a
cooling
fan
to
prevent
overheating.
TENSILE
STRENGTH:
The
maximum
stress
a
material
can
withstand
before
it
breaks;
expressed
in
pounds
per
square
inch.
TEXTILE:
That
which
is
or
may
be
woven.
Comes
from
the
Latin
“Texere,”
which
means
to
weave.
Hence
any
kind
of
fabric.
THREAD
COUNT:
The
number
of
warp
and
filling
yarns
in
a
fabric,
commonly
expressed
in
square
inch.
THRESHOLD
LIMIT
VALUES
(TLV):
Represents
the
air
concentrations
of
chemical
substances
to
which
it
is
believed
that
workers
may
be
exposed
daily
without
adverse
effect.
THROW,
BLOW:
Distance
an
air
stream
travels
from
an
outlet
to
a
position
at
which
air
motion
reduces
to
a
velocity
of
50
FPM.
TIP
SPEED:
Fan
wheel
velocity
at
a
point
corresponding
to
the
outside
diameter
of
the
wheel
blades;
normally
expressed
in
feet
per
minute
(circumference
times
RPM).
TLV
(THRESHOLD
LIMIT
VALUE):
A
registered
trademark
for
an
exposure
limit
developed
by
the
American
Conference
of
Governmental
Industrial
Hygienists
(ACGIH).
A
listing
of
TLVs
may
be
found
in
the
ACGIH’s
Documentation
of
the
Threshold
Limit
Values
and
Biological
Exposure
indices
for
1988-1989.
TORQUE:
A
force
that
produces,
or
tends
to
produce,
rotation.
Commonly
measured
in
feet
per
pounds
or
inches
per
pounds
A
force
of
one
pound
applied
to
the
handle
of
a
crank,
the
center
of
which
is
displaced
one
foot
from
the
center
of
the
shaft,
produces
a
torque
of
one
foot
per
pound
on
the
shaft
if
the
force
is
provided
perpendicular
to,
not
along
the
crank.
Torque
can
be
calculated
by:
Torque
(ft.-lbs.)
=
HP
x
5250
RPM
TOXIC
RELEASE
INVENTORY
(TRI):
A
listing
of
pollutants
and
emission
levels
from
each
major
source.
TP:
Total
pressure.
The
sum
of
velocity
pressure
plus
static
pressure.
TPI:
Twist
Per
Inch.
TPY:
Tons
Per
Year.
TRAVERSE:
A
method
of
sampling
points
in
a
duct
where
pressure
readings
will
be
taken
to
determine
velocity.
A
traverse
divides
the
duct
into
equal,
evenly
distributed
areas
that
are
each
tested,
compensating
for
errors
caused
by
uneven
gas
flow
in
the
duct.
TROUGH
HOPPER:
Dust
discharge
that
has
an
outlet
slot
along
the
entire
length
of
the
hopper
for
transfer
of
material
directly
into
a
screw
conveyor
or
other
continuous
material
transfer
system.
TSCA
(TOXIC
SUBSTANCES
CONTROL
ACT.):
Administered
by
the
EPA,
was
passed
by
Congress
to
protect
human
health
and
the
environment
by
requiring
testing
and
necessary
use
restrictions
to
regulate
the
commerce
of
certain
chemical
substances.
TUBBEAXIAL
FAN:
Axial
fan
without
guide
vanes.
TUBESHEET:
The
steel
plate
that
bags
and
cages
are
suspended
from.
Separates
the
clean
air
and
dirty
air
sections
of
the
baghouse.
Sometimes
called
cellplate,
a
term
usually
used
for
inside
collector
baghouses.
TUBULAR
CENTRIFUGAL
FAN:
Fan
with
a
centrifugal
impeller
withing
a
cylindrical
housing
discharging
the
gas
in
an
axial
direction.
TURBULENT
FLOW:
Airflow
in
which
true
velocities
at
a
given
point
vary
erratically
in
speed
and
direction.
TURNING
VANES:
Baffles
put
in
a
duct
to
straighten
out
the
air
flow.
TWA
(TIME
WEIGHTED
AVERAGE):
Employee’s
average
airborne
exposure
which
cannot
be
exceeded
in
any
eight-hour
work
shift.
TWA
is
set
by
OSHA
and
expressed
in
mg/m.
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