Zero pressure on 1100 pump.

[Matt Savage]

We're running an 1100 with a quat pump for about 18 months with no issues. However today the pressure suddenly died on us.

Yesterday we were running normal phase, (Ethyl Acetate/Hexane) flushed out the system with IPA before running reverse phase with changed to a 50:50 water:methanol system which was fine for a few hours. We then changed to a 20:80 phosphate buffered (pH7) water:MeOH system (first time we've tried it) and within minutes we'd lost all pressure, no matter what flow rate we try.

I'm guessing that the buffer is responsible. Which begs the questions why and how do we fix it?

Matt

[Mark Tracy]

Your seals became swollen in the NP mobile phase and conformed nicely to the pistons, but then shrank in the RP mobile phase. There are different seals for RP and NP; get the right kind. You can get away with using the wrong kind for a quick project, but not for extended use.