GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 20
SAMPLE
INLET
The
length
of
time
it
takes
gas
to
flow
from
the
sample
source
to
the
GDS
‐
68XP
inlet
should
not
exceed
30
seconds
to
ensure
that
“fresh”
sample
is
available
at
the
beginning
of
each
measurement
cycle.
For
¼”
OD
stainless
steel
tubing
and
sample
flow
rates
of
approximately
0.5
liters
per
minute,
the
maximum
length
should
be
no
more
than
60
feet
(~20
m).
Smaller
diameter
tubing
will
allow
longer
runs
but
may
be
subject
to
clogging
if
the
sample
contains
particulate
or
moisture.
Larger
diameter
tubing
should
be
avoided
due
to
the
internal
volume
of
entrained
gas.
Figure 5-6: Inlet Tubing Recommendations
In
the
event
that
the
GDS
‐
68XP
must
be
mounted
at
a
greater
distance
from
the
sample
pickup
point,
the
combination
coalescing
/
bypass
filter
is
recommended.
This
filter
includes
a
bypass
port
and
bypass
valve
that
can
be
opened
slightly
to
enable
a
continuous
flow
of
sample
from
the
pickup
point
to
the
filter
input,
ensuring
that
fresh
sample
is
always
available.
IMPORTANT
:
WHEN
CONFIGURED
FOR
SAMPLE
DRAW,
THE
GDS
‐
68XP
SAMPLE
PUMP
IS
CAPABLE
OF
PULLING
UP
TO
7.0
PSI
VACUUM,
ENOUGH
TO
LIFT
WATER
OVER
15
FEET.
CARE
SHOULD
BE
TAKEN
NOT
TO
SUBMERGE
THE
SAMPLE
PICKUP
POINT
IN
LIQUID.
INJESTED
LIQUID
IS
NOT
COVERED
UNDER
WARRANTY.
If
a
unit
that
has
been
configured
for
sample
draw
is
connected
to
a
sample
source
with
pressure
higher
than
ambient,
an
additional
low
‐
pressure
regulator
or
flow
restriction
device
should
be
installed
in
the
sample
inlet
line
before
the
GDS
‐
68XP.
This
will
allow
the
sample
flow
to
be
adjusted
to
match
the
purge
air
flow.
Inlet
Delay
Calculation
For
¼”
OD
stainless
steel
tubing,
allow
5
seconds
delay
for
every
10
feet
of
sample
line.
Max
60
Feet
With
¼”
OD
Tubing
Mount
GDS
‐
68XP
above
sample
point
if
possible