Appendix
12
Appendix
12.1
Determination
of
Emissivity
Emissivity
is
a
measure
of
an
object’s
ability
to
absorb
and
emit
infrared
energy.
It
can
have
a
value
between
0
and
1.0.
For
example
a
mirror
has
an
emissivity
of
<
0.1,
while
the
so
‐
called
“Blackbody“
reaches
an
emissivity
value
of
1.0.
If
a
higher
than
actual
emissivity
value
is
set,
the
output
will
read
low,
provided
the
target
temperature
is
above
its
ambient
temperature.
For
example,
if
you
have
set
0.95
and
the
actual
emissivity
is
0.9,
the
temperature
reading
will
be
lower
than
the
true
temperature.
An
object’s
emissivity
can
be
determined
by
one
of
the
following
methods:
1.
Determine
the
actual
temperature
of
the
material
using
an
RTD
(PT100),
a
thermocouple,
or
any
other
suitable
contact
temperature
method.
Next,
measure
the
object’s
temperature
and
adjust
emissivity
setting
until
the
correct
temperature
value
is
reached.
This
is
the
correct
emissivity
for
the
measured
material.
2.
If
possible,
apply
flat
black
paint
to
a
portion
of
the
surface
of
the
object.
The
emissivity
of
the
paint
must
be
above
0.98.
Next,
measure
the
temperature
of
the
painted
area
using
an
emissivity
setting
of
0.98.
Finally,
measure
the
temperature
of
an
adjacent
area
on
the
object
and
adjust
the
emissivity
until
the
same
temperature
is
reached.
This
is
the
correct
emissivity
for
the
measured
material.
80
MID
