O
PERATION
M
ANUAL
P
ROMO
®
2000
P
ALAS
®
G
MB
H,
M
ARCH
2010,
V
ERSION
V001032010
33
The
sensor
is
only
made
from
optical
and
mechanical
parts,
i.e.
no
spark
can
develop.
(Attention,
exception:
sensors
with
heatable
cuvette!)
For
measurements
in
chemically
aggressive
gases,
the
cuvette
can
be
produced
of
special
stainless
steel.
A
grounding
cable
avoids
a
possible
triboelectric
charging.
Thus,
this
particle
measurement
system
makes
it
possible
to
measure
at
places
difficult
to
access,
e.g.
at
the
outlet
of
a
very
high
chimney.
6.6
Border
zone
error
Border
zone
error
means
the
deviation
of
particle
size
and
concentration
at
the
edge
of
the
mea
‐
suring
volume,
caused
by
the
Gaussian
distribution
of
the
laser
beam.
The
size
range
is
measured
with
a
too
high
fine
fraction.
The
broader
the
particle
range,
the
worse
the
border
zone
error.
The
preliminary
model
PCS
2010
already
had
a
border
zone
error
correction.
Two
photomultipliers
with
measurement
volumes
of
different
sizes
were
compared.
Did
the
comparison
not
correspond
to
the
specified
values,
the
particle
was
discarded.
Thus,
the
border
zone
error
was
corrected,
but
not
eliminated.
The
T
‐
aperture
technology
of
Promo®
allows
an
exact
determination
of
size
and
concentration
of
the
aerosol.
6.7
Impact
of
the
device
parameters
Border
zone
error
The
particle
size
spectrum
is
measured
with
too
many
fines.
The
broader
the
particle
size
spectrum
is
measured,
the
more
important
becomes
the
border
zone
error.
Coincidence
error
The
particle
size
spectrum
is
measured
too
coarse,
the
particle
concentration
is
measured
too
small.
Counting
efficiency
The
lower
counting
efficiency
results
in
a
shifting
of
the
particle
size
distribution
towards
coarse
particles
because
the
fines
are
undervalued.
The
upper
counting
efficiency
similarly
undervalues
the
coarse
particles.
The
quantity
is
determined
incorrectly.
When
measuring
with
several
particle
counters,
the
counting
efficiency
difference
between
the
used
counters
has
to
be
known.
Only
then,
the
results
are
comparable!