- Hewlett-Packard Reference Manual

Preventive Maintenance
Packed column inlet
161
4. Fully open the mass flow controller counterclockwiseand wait 1 to
2 minutes to ensure equilibrium.
5. Turn off gas to the inlet at its source.
6. Wait 10 minutes while observing carrier source pressure. If it drops
less than 7 to 14 kPa (1 to 2 psi), the system (through the inlet
column fitting) is considered leak free.
Evidence of leakage requires the inlet system be leak•checked.
Repressurize the system as necessary, and
Use a suitable leak•detectionfluid to check for leakage fittings.
Correct or replace leaking fittings as needed.
Caution
Leak•detectionfluids often leave contaminating residues; after each
application, the area checked should be rinsed with CH
3
OH (methanol)
and allowed to dry.
After verifying fittings are leak•free,there are two locations at the
inlet itself where leakage may occur: at the septum, and at the
column connection.
- The column connection is checked using a leak•detectionfluid.
- The septum is checked with a bubble flow meter by pressing its
rubber inlet tube tightly onto the needle entrance in the septum
retainer nut or simply replacing the septum.