Pump pressure is too high for our Agilent PL-GPC 50

Good Morning,

As I indicated in the heading title, the pressure for our PL-GPC 50 is too high.

Moreover, I specify we changed both inlet/outlet valves with their filters , we also changed both filters in the PTFE tubing from the inlet check valve. That means all the filters are changed and also the plunger seal from the pump head.

We also changed the in-line filter before the the initial-forward column then, we flushed both columns but our problem of  too high presure still remains.

QUESTION : do we have to replace the O-Ring of the drain valve knob ?? (because it was not already changed !!! )

QUESTION : to solve this pressure bug, what we have to do ?? (because all of our filters are already changed !!! )

NB : our software seems to be okay so it is not in this direction to foresee the problem!!

In advance I thank you for your eventual clues and tips to solve our high pressure problem because I do indicate that many filters are changed.

In order to stay in touch with me, you can write me at my following E-mail: patrick.thomas@obspm.fr

Thank you again for your help.

All my best regards,

Patrick Thomas

patrick.thomas@obspm.fr