
GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 14
SAMPLE
DRAW
CONFIGURATION
In
addition
to
low
and
high
positive
pressure
versions,
the
GDS
‐
68XP
can
be
configured
to
draw
a
sample
from
ambient
pressure
sources.
In
this
configuration
the
pump
operates
continuously
to
pull
from
both
purge
air
and
sample
sources
(See
Fig.
4
‐
4).
Figure 4-4: GDS-68XP Flow Diagram (Sample Draw)
SENSOR
CONSIDERATIONS
The
GDS
‐
68XP
supports
electrochemical
sensors
for
hydrogen
sulfide,
THT
and
mercaptan.
Each
sensor
contains
a
fixed
amount
of
chemical
electrolyte
that
reacts
with
the
target
gas
to
create
free
electrons
that
are
amplified
and
measured.
Once
the
electrolyte
is
depleted,
sensor
output
will
diminish
and
the
sensor
must
be
replaced.
IMPORTANT:
TOXIC
SENSORS
ARE
SUBJECT
TO
ACCELERATED
DETERIORATION
IF
POWER
IS
NOT
APPLIED
WITHIN
3
MONTHS
OF
SHIPMENT
FROM
GDS
CORP.
Purge
Air
Pump
Flow
Switch
Cal
Gas
Inlet
Sample
Inlet
Flow
Meter
Sample
Outlet
Sensor
Flow
Cell
Run
/
Cal
Valve
3
‐
Way
Valve
Purge
Air
Inlet
Filter