Man263.pub
Chapter: Troubleshooting
Topic: LeakChecking your GC
The thirdmethodof leak checking
is call the
"pressuredrop"
test.
The pneumatic system is plugged
at the endof the gas flowpath.
Thismay be the outlet of the de-
tector or theend of the column.
Use a swagelok fittingor a
swagelok nut with aGC septum to
makea gas tight seal. If the plug
leaks, the test will not work.
The system is then pressurized
using theEPC ( electronic pres-
sure regulator ) built-in to theSRI
GC. TheEPC is then turneddown
( or off ). Because theendof the
gas flowpath is plugged, the gas
is trapped ( under pressure ) in the
pneumatic system. If there is a
leak, the gas pressurewill drop. If
theentire system is leak free, the
pressurewill remain formanymin-
utes before it slowly drops. The
rate at which thepressure drops is
indicative of themagnitudeof the
leak
Usea swagelok capor plug fitting, or useaGC
septum ina swagelok nut tomakea leak-tight
seal
Plug thepneumatic system off at theendof the
gas flowpath. Youhave to knowwhere thegas
exits to theatmosphere
Pressurize the system using theEPC, then turn
down theEPCpressure
Monitor the system pressure to see if it
drops fast, slowly or not at all
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