Troubleshooting - Varian 212-LC Manual Del Usuario

Troubleshooting

Problem
Erratic pressure
Operating
pressure is lower
than normal
1
This problem may not be easy to detect. On the inlet side of the pump there is a slight vacuum, so air
will leak into the pump rather than solvent leaking out. There will be no visible sign of a leak. To detect
this problem, make sure that there is no air in the inlet lines, then open the outlet fitting and watch for air
bubbles coming out (place a drop of solvent at the outlet fitting to observe air bubbles). If you continue to
observe air bubbles after 60 seconds, then air is probably entering the head from the inlet fitting, a leaky
pump seal, or an insufficiently tightened inlet housing.
2
This symptom is normal after replacing a pump seal or piston. Wet the seal and the inside of the pump
head with IPA to reduce the time it takes to eliminate air from the head.
Cause
Dirty inlet check valve
Dirty inlet check valve
Clogged solvent filter
Leak at solvent inlet line
Worn pump seal or piston
2
Air in pump head
Not using degassed
Solvents
Bubbles in inlet line
Worn seal or piston
Air in pump head or inlet
line
Clogged solvent inlet filter
Dirty inlet check valve/
outlet check valve
3
Leaky fitting
Remedy
Remove check valve cartridge and sonicate in
MeOH for 1 minute, maximum. Blow air
through in direction of arrow and reinstall.
Replace with new check valve. Varian uses
the same check valve cartridge for both inlet
and outlet.
Replace with new filter.
1
Tighten fitting or replace.
Replace seal. Inspect piston and replace if
worn.
Purge pump for 30 seconds, then operate at
1,000 psi or higher. The air will dissolve in the
solvent and be expelled within about
30 minutes.
Degas, preferably using vacuum and
sonication.
Degas solvent. Replace solvent inlet filter.
Make sure solvent bottle still has solvent.
Replace seal. Inspect piston and replace if
worn.
Purge pump for 30 seconds, then operate at
1,000 psi or higher. The air will dissolve in the
solvent and be expelled within about
30 minutes.
Clean or replace with new filter
Remove check valve cartridge and sonicate in
MeOH for 1 minute, maximum. Blow air
through in direction of arrow and reinstall.
Tighten or replace fitting
28