
GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 22
SAMPLE
EXHAUST
Changes
in
ambient
pressure
will
affect
the
output
from
all
electrochemical
sensors,
and
allowing
the
sample
to
exhaust
directly
to
atmosphere
will
minimize
these
affects.
Long
runs
of
tubing
connected
to
the
sample
outlet
may
increase
the
backpressure
inside
the
sensor
flow
cell
and
cause
higher
than
normal
readings.
Hydrogen
sulfide
is
a
heavy
gas
and
will
tend
to
‘back
up’
inside
sample
exhaust
lines
that
extend
vertically
for
too
great
a
distance.
Figure 5-8: GDS-68XP Exhaust Tubing
IMPORTANT
:
DO
NOT
RESTRICT
SAMPLE
EXHAUST
OUTLET.
PRESSURE
IN
THE
SAMPLE
FLOW
CELL
MAY
DAMAGE
THE
SENSOR
AND
WILL
RESULT
IN
INCORRECT
READINGS.
IMPORTANT
:
WHEN
INSTALLING
THE
GDS
‐
68XP
OUTDOORS,
MAKE
SURE
SAMPLE
EXHAUST
IS
PROTECTED
BY
A
SCREEN
OR
FILTER
TO
KEEP
INSECTS
FROM
ENTERING
THE
EXHAUST
PORT
AND
NESTING
IN
THE
SENSOR
FLOW
CELL.
DANGER
:
MAKE
SURE
EXHAUST
GAS
IS
DIRECTED
AWAY
FROM
PERSONNEL
AND
EQUIPMENT,
ESPECIALLY
SUMPS
OR
LOW
‐
LYING
AREAS
WHERE
HEAVY
GASES,
SUCH
AS
HYDROGEN
SULFIDE,
CAN
BUILD
UP
OVER
TIME.
HYDROGEN
SULFIDE
IS
DEADLY
AND
EXPOSURE
CAN
RESULT
IN
INJURY
OR
DEATH.
Maximum
Rise
Limit
the
vertical
exhaust
to
a
point
no
greater
than
15
feet
above
the
top
of
the
GDS
‐
68XP.
Sample
Release
to
Atmosphere
Remember
that
sample
exhaust
is
only
released
to
the
atmosphere
during
sample
measurement
time,
not
continuously
15’
/
5
m
maximum