
GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 32
8
OPERATION
AND
MAINTENANCE
NORMAL
OPERATION
Once
setup
is
complete,
user
intervention
is
not
required
and
the
GDS
‐
68XP
automatically
measures
and
outputs
the
gas
concentration
value
on
an
interval
set
by
the
sequence
switch.
When
the
GDS
‐
68XP
is
running
a
sample
sequence,
the
red
LED
(“L1”)
will
be
flashing.
Do
not
attempt
to
adjust
any
settings
or
perform
a
calibration
during
a
sample
sequence.
A
complete
sequence
usually
takes
between
10
and
15
minutes
to
complete.
To
determine
the
current
status
of
the
sequence,
count
the
number
of
L1
flashes
and
refer
to
Figure
6
‐
3.
During
purge
/
hold
mode,
the
green
LED
(“L2”)
will
be
flashing,
the
gas
detector
can
be
calibrated
and
the
sequence
time
can
be
adjusted.
To
change
the
sequence
time,
refer
to
Figure
3
‐
2
and
modify
the
SEQUENCE
SWITCH
setting
as
desired.
Changing
the
sequence
switch
will
not
change
the
current
delay
time,
but
will
set
the
delay
for
the
next
scheduled
sample
cycle.
If
it
is
desired
to
start
a
new
cycle
immediately,
change
the
switch
setting
and
then
press
and
hold
the
RUN
button
for
five
seconds.
COLD
WEATHER
OPERATION
The
GDS
‐
68XP
is
designed
for
accurate
and
reliable
operation
across
a
wide
range
of
operating
conditions.
Once
running,
the
GDS
‐
68XP
generates
sufficient
heat
to
maintain
operation
to
0°F
ambient.
However,
if
the
unit
has
been
powered
off,
care
should
be
taken
during
startup
to
make
sure
the
purge
air
pump
temperature
is
above
32°F
prior
to
the
application
of
DC
power.
To
reduce
the
possibility
of
pump
damage,
in
extremely
cold
weather
GDS
Corp
recommends
the
200W
AC
heater
be
turned
on
for
several
hours
prior
to
applying
DC
power
to
the
system.
In
addition,
if
the
unit
is
to
be
left
unpowered
during
extremely
cold
weather,
GDS
Corp
recommends
the
sensor
be
removed
and
stored
in
a
warm
location.
NORMAL
MAINTENANCE
Standard
maintenance
for
the
GDS
‐
68XP
consists
of
periodic
checks
on
flow
settings
and
sensor
calibration.
Each
time
a
toxic
sensor
is
calibrated,
a
Sensor
Life
reading
will
appear
that
gives
an
approximate
indication
of
the
remaining
sensitivity.
Sensor
Life
is
not
necessarily
linear
and
a
rapid
reduction
in
the
senor
life
reading
can
be
due
to
temperature
extremes,
high
levels
of
target
gas,
the
presence
of
certain
gases
that
‘poison’
toxic
sensors
and
other
environmental
factors.
Always
check
the
flow
meter
for
the
presence
of
moisture.
In
the
event
that
moisture
or
liquid
is
drawn
in
the
GDS
‐
68XP,
the
entire
unit
should
be
disassembled
and
cleaned.
In
some
cases
the
flow
meter
or
flow
switch
may
need
to
be
replaced.
If
liquid
is
drawn
into
the
GDS
‐
68XP,
always
inspect
the
sensor
for
signs
of
damage.