Chapter: Troubleshooting
Topic:
LeakChecking your GC
The thirdmethod of leak checking
is call
the
"pressure drop" test.
The pneumatic system is plugged
at the endof the gas flowpath.
Thismay
be
thecuuet of the de–
tector or the end of the column.
Use a swage10k
fittiog
or a
swagelok nutwith aGC septum
to
make a gas tight seal. If the plug
leaks, the test will not work.
~
-.,.
Plug the
proeumatic:
system
rIf
at
the
end
r:A
the
gas
flC>N
path.
You
have
to know
v.nere
the gas
",.;ts
10 the
atmosphere
The systemis then pressurized
using the EPC ( electronic pres–
sure regulator) blJill-in to!heSRI
GC. The EPC is then turneddown
( or off ), Because the end
of
the
gas
flow
path is plugged, the gas
is trapped ( under pressure ) in the
pneumatic system. If there is a
leak, the gas pressure will drop, If
the entire system is leak
free ,
the
pressurewill remain for manymin–
utes before it slowly drops, The
rate atwhich thepressure drops is
indicative of themagnitude of !he
leak
use
II
swegeIok
cap
or
~ug
litIirg.
or
use
a
GC
septum
ina, ,,
gelol<
nul lo
make
a
leak-tight
...
ELECTRONICGAS
PRESSURECONTROLS
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Monilol' the
systempressure
10
see
If
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,
drops
fast.
slowly or
not
8l
all
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