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Jun 2001
Inlets
Agilent 6890 Gas Chromatograph Service Manual
Cool On-Column Inlet 230
Leak testing EPC and manual inlets
Leak testing the EPC module only
Occasionally, to track down small leaks, you will need to isolate the EPC
module from the inlet weldment and leak test the EPC module separately.
1. On the keyboard, turn off pressure to the inlet being tested.
Press
[Front Inlet] or [Back Inlet], scroll to the Pressure field
and press
[Off].
2. Use a Torx T-10 screwdriver to remove the screw in the plumbing block
on the front of the module. Remove the plumbing block from the EPC
module, being careful not to lose the O-rings between the block and the
module.
3. Replace the inlet’s plumbing block with the leak test block (part no.
G1530-20660) from the leak test kit (part no. G1530-60960). Make sure
you install O-rings between the block and the EPC module to create a seal.
The leak test block is a special fitting that plumbs the carrier gas
coming out of the module directly back into the septum purge flow
path on the module. It allows the carrier gas and septum purge to
function normally as if an inlet were present.
4. Perform the normal leak test for the EPC inlet as described previously in
this section. With the inlet removed, the internal volume is smaller and
a pressure loss of 1.0 psi in 10 minutes is considered leak-free.
Forward pressure valve leaks
Occasionally an increase in pressure, rather than a decrease may be observed.
This is usually due to slight leakage into the module across the forward
pressure control proportional valve. Although slight leaks of this nature do
not create chromatographic problems, they may obscure other small leaks
that do cause problems by allowing air into the system.
To check for internal valve leakage:
1. Remove the supply pressure at the carrier inlet fitting, and quickly cap
the fitting with a Solid 1/8-inch Vespel plug and a Swagelok nut.
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