Cannot compress either the primary or accumulator on my H-Class

<p>Yesterday after completing a 30 minute analysis, we noticed that our H-Class system pressure was never stable.  After doing a small investigation we noticed that the pump seal wash line was dry.  After priming the seal wash we did a diagnostic leak test and neither the primary or accumulator were able to pressurize above 3000 psi.  I was able to put some flow on the system and achieve 11,000 psi, but it wouldn't stabilize.  We haven't seen any leaks, but I'm wondering if either of the pump seals were damaged after running dry?  Also, I am hearing a strange double-clicking which appears to be coming from the primary pump.  I was told that a double-click means that the seals are dry?  Could they still be dry after priming like crazy, or again might they be damaged?</p><p></p><p>Please help.  I'm totally confused at this point...</p><p></p><p>Thank you!   </p>


  • Shannon,

    That "double clicking" that you hear is the Seal Wash pump.  It is usually a single click about every 5 minutes (depending on the setting in the last instrument method that was run).  The double clicking is an indication that the pump is dry and will need to be primed.  This can be done from the QSM Console page.  Select  Maintain > Prime Seal Wash.  You will hear that double clicking continuously.  When the pump is primed, the sound will change to a single click (allow the prime to continue for an additional 30 sec to a minute to make sure that the lines are sufficiently wet).

    This Seal Wash system is designed to wash the particulate matter from the back of the plungers inside the head (just behind where the plunger drives into the seals).  It is important to keep these particulates off of the plunger so that they do not get pushed into the High Pressure seal.  Chances are good that if your pump ran dry some of this material has damaged the pump seals and that would explain why you can not get the pump to reach pressure and/or the pressure fluctuation.  If you have never replaced the plungers/seals, or been trained to do so, you may need to contact a Waters Field Service Engineer.

    Hope this helps,


  • Thanks Marc.  Is it possible to wash the high pressure seal (with MeOH or ACN) or to visually identify damage?  I have been trained on how to disassemble the pumps to gain access to the seals.  However, I don't have any replacement seals on hand.  So if a particle got into the high pressure seal, maybe I can flush it out?

  • So my Waters service engineer came to fix my problem.  Apparently in trying to protect my new UPLC I filtered part of my mobile phase with a nylon filter, which is apparently a BIG no, no, which clogged and subsequently ruined the seals on both the primary and accumulator pumps .  All is well now, and I am getting AMAZING chromatography!!!

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