UPC2 degasser H/W fault

Hi there, 

I have a ACQUITY UPC2 system that is experiencing a "Degasser reported H/W fault" this was diagnossed as an error with the degasser vacuum pump as the degasser pressure only would drop to 2.0 psi instead of the operating 0.9 psi.  The pump was replaced an upon start up the degasser pressure drops to 0.8, but it does not hold and creeps back up to 1.6 psi before the fault repeats.  Does anyone have any troubleshooting suggestions. 



  • Hi dmachin,

    The error that you describe can be caused by a few different things.  One of those, of course, is the degasser motor but there are other common causes also.  This troubleshooting guide from the Waters Knowledge Base should help you walk through the easiest to diagnose and fix to the more difficult solutions.  Hope this helps!


  • Hi Marc, 

    Thanks for this, I have already went through those steps which led to the replacement of the vacuum pump for the degasser.  It now reaches operational vacuum upon startup but drifts above 1.5 and faults. 

  • That sounds like a leak in the tubing or one of the vacuum chambers.

  • Thanks marc, this is the second pump so i think it would be weird for it to be the vacuum chambers and I have switched out tubing and directly connected the vacuum to the pressure transducer (to test the tubing one at a time.  The fault is very consistant.  Can the pressure trasducer leak?

  • Yes.  The transducer can fail.  It usually fails totally but I imagine that it could have a leak that causes the symptom that you describe and it does sound like you have eliminated all of the other usual suspects.  You may need to contact your local service team to have that replaced or the part ordered, but if it helps the part number is 700002511.
  • Thank you marc, this has been most helpful even if we havent quite got it fixed,  I opend a service ticket for this issue but have had a very hard time getting responses so this was a good resource 

  • Glad I could help!

  • Hi dmachin, I had this same problem and found that it was both a bad vac pump and bad PCB board. Here is what I was seeing. Some screenshots of the error, and degasser PSI pre and post maintenance. Replacing both fixed the issue. Hope it helps!