Varian 450-GC, User Manual

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Pulsed Discharge Helium Ionization Detector (PDHID) - Detectors
Varian, Inc. User Manual 450-GC Page: 301
5. Observe the needle of the output pressure gauge for 15 minutes. There will
be a slight initial drop, but if it doesn’t move after that, consider that all the
connections are tight.
6. If necessary, use an electronic leak detector to locate any leaks. If a leak
detector is not available, tighten all the fittings ( including the output
pressure gauge) and repressurize the system for another test.
7. Uncap the outlet tube of the purifier and purge the system for 15 to 30
minutes at 60 - 80 mL/min to eliminate air from the purifier getter material.
Connecting the Discharge Gas to the Detector
1. If you are supplying the GC from the helium purifier, use the Valco ZX1
cross. (The cross supplies an extra port for a blank helium run.) Otherwise,
use one of the Valco 1/16" unions (ZU1) to connect the outlet tube of the
purifier to the inlet of the supplied discharge gas.
2. Restrictor (TGA-R-35F80P).
3. Connect the outlet end of the restrictor to a flow measuring device. Adjust
the helium pressure to 80 psi to obtain a continuous flow of ~35 mL/min.
4. After setting the flow rate, connect the outlet of the restrictor to the
discharge gas inlet tube (labeled “INLET”) which comes out the side of the
detector.
Capillary Column Connection
If the capillary column adapter is installed in the column inlet:
1. Make a mark on the column 11.4 cm from the end.
2. Remove the knurled nut and plug from the capillary column
adapter in the column inlet at the bottom of the detector. Slide
the nut over the end of the column, followed by the appropriate
column ferrule (FS.4 or FS.5, or ZF.5V for megabore).
3. Seat the ferrule in the detail of the column adapter and begin
sliding the column through the capillary column adapter and
into the column inlet.
4. Get the nut started on the threads and tighten it until you feel it
contact the ferrule, then back off half a turn. Slide the column
into the column inlet until the mark is flush with the surface of
the knurled nut and secure the column in the adapter by
tightening the knurled nut finger tight only.