Chromatography Forum

One of our Alliance units has been showing higher than usual system pressures lately and today displayed the following error message, "Alert: Plunger homing over pressure (0)", during a boot up when I went to test it.

Removing the in-line filter and replacing it with a piece of tubing gave the same error message but we managed to get it to boot by opening the Purge valve on the low pressure side. I checked the in-line filter and it is clean.

Pumping 100% acetonitrile through the pump, with no column attached gave a very high back pressure of over 800 psi. Normally this is around 80 psi.

Has anyone know what might be happening here and what your recommendations would be for servicing?

Thanks very much then.

Hm, what comes to mind, could be a plugged injection needle?

Or secondly the allingnement of the seals in the sealpack went off

Thanks very much, Hollow,

We will check these later today.

Our HPLC system was fixed, it appeared there was a small blockage in the high-pressure check valve, this was probably a small amount of dust?

Anyway, thanks your reply & ideas, "Hollow".

Thank you for your reply and let us know what was the issue.

just curious:
By high pressure check valve you mean one of the three high.pressure valves of the injection system? Which one was it?

It was the check valve at the primary solvent pump – the injector valves were fine. The dirt was possibly from buffer we used in the system.
Best Regards.