User guide

138 Advanced User Guide
6 Checking for Leaks
To Perform a COC Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth. See “To Check for External Leaks”.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
1 Gather the following (see Consumables and parts for the
COC inlet):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Column nut
• New septum
• ECD/TCD Detector plug (part no. 5060- 9055)
2 Load the inlet maintenance method and wait for the GC to
become ready.
3 Remove the column, if installed.
4 Plug the column fitting with a column nut and no- hole
ferrule.
5 Remove the old septum and replace it with a new one. See To
change a septum on the COC inlet.
The test can find leaks at the: The test cannot find leaks at the:
septum column fitting
septum nut or cooling tower gas supply bulkhead fittings to the
flow module
seals within the tubing between the
inlet flow module and the inlet body
inlet body