Inlets and valves
6850
6850
Released: April 2004 6850 Series Gas Chromatograph Service Procedures 119
NOTE: When the inlet pressure or flow is turned
off, the safety shutdown feature, including the
audible alarm, is not functional. The inlet will not
automatically shut down. This will provide you
with unlimited time to locate leaks.
7. Note the “Actual” reading on the display and
monitor the pressure for 10 minutes.
You can use the stopwatch feature of the
6850 GC to monitor the time. Press
[Time] and then [Enter] to start
timing, then toggle between the time and the
pressure reading with the [Time] and the
[Front Inlet]/[Back Inlet]
keys.
• If there is less than 0.5 psi pressure
loss, consider the system leak tight.
• If pressure loss is much greater than
0.5 psi, there is a leak that must be
found and corrected. Note, however,
that you may want to slightly decrease
the leak test time based on the internal
inlet volume which changes with the
liner type used (smaller volumes =
shorter acceptable leak test times). See
“Correcting leaks (all inlets)” on
page 1-129.
8. When the system is considered leak tight,
the caps may be removed, the column rein-
stalled, its dimensions configured at key-
board, and the desired pressure and flow
rate set.
Leak testing the PTV module only
Occasionally, to locate small leaks, you will need
to isolate the EPC module from the inlet weld-
ment and leak test the EPC module separately.
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