Agilent 1260 High pressure

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6 posts Page 1 of 1
Agilent 1260 with isocratic pump is having high pressure. The mobile phase is ~50/50 water and methanol so no salt build up or algae build up. When the pump frit was changed it was very black. I changed the frit, the plunger seals and the plungers. Pressure still high >400. I changed the guard column and pressure went down to ~210 bar which was still higher than normal (normal ~170 bar). Pressure increased again to >400 bar. This time it was high when the purge valve was open indicating that it was in the pump, however later that was not the case. Pressure would drop when purge valve open. I disconnected lines, changed lines and switched from main pass to bypass mode (pressure remained constant). Changed guard column again because that was where the pressure did not go down. Pressure went back down to
~210. Later it went back up again. Removed guard column and it went back down again. This time to ~170. Something seems to be in the system plugging the guard column. Now without the guard column the pressure is increasing again. I've changed the lines from column heater to column/guard column and from rotor seal to column heater. Any ideas on what to do next. If I flushed system with IPA would it help, could it be a pump issue. I cannot find anything that says the ball outlet or the inlet valve could be the problem.
Many comments and questions in no order:

50/50 Water : MeOH is of course a worst case scenario for high pressure as that mixture yields the highest back pressure under normal conditions. Have you tried flushing the system with pure water and also pure IPA (at low flow rates)?

A black PTFE frit indicates a lot of general abuse and probably no maintenance. Was this a auction purchased system?

Did you clean out the LP Teflon solvent lines, install new solvent pickup filters, insure the mobile phase bottles were clean?
Did you use factory Agilent piston seals and pistons (We know of a NJ service company that uses aftermarket parts and the systems often leak afterwards)?
Did you flush out the pump head with solvent before installing the new parts? Did you flush out the prime purge valve with solvent before installed the new PTFE frit? Did you purge the system with IPA (or pure water, depending on which pressure test method was chosen), plug the prime purge valve with a blanking nut and then run a formal pressure test? If so, what were the results? *That test rules out the other components.

In the meantime, do not connect the system to any columns. Route it to a waste until you can show the pump is clean and runs reliably, then connect a calibrated restriction cap to it and check again, under high pressure (NO COLUMN). "Isolate and test".
I have not tried to wash with IPA that was one of my questions in my post. I can try.

The black does indicate wear. My company believes in fixing not Preventative (not my call).

Mobile Phase bottles are clean as is the filter in the mobile phase.

I did not flush after changing parts or flush out the prime purge valve. I never have and have not had an issue but there is always a first time.

I have not done a pressure test, but can try. The component causing the pressure problem seems to be migrating. I'll think I've got it back to normal, set everything back up and it runs good for about a day and then it happens again.

What is a calibrated restriction cap?
Hi blakeyk,

For example, the Agilent / HP HPLC System Restriction Calibration Capillary Assembly, Part Number G1312-67500.

https://www.agilent.com/store/en_US/Pro ... 1312-67500
MattM
"The HPLC Restriction Capillary; Troubleshooting, Qualification and Running Without A Column": https://hplctips.blogspot.com/2018/04/the-hplc-restriction-capillary.html
Hi blakeyk,

How is the pump troubleshooting going?
MattM
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