Waters QSM degasser not holding vacuum

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6 posts Page 1 of 1
Hey ChromForum

We are running a Waters UPLC system with a QSM that has the degasser built in. In the last few days it has been impossible to run because the degasser keeps going over the pressure threshold. I have tried priming and running the degasser health check but it can never complete as it errors out when it reaches the threshold.

The only advice I got from Waters was to do this with methanol on every line. Today, it has been sitting off for the weekend and the vacuum held for almost an hour but then exceeded the limit again, and was, once again, unable to complete the health check.

Is there anyway I could repair this myself? I can't find any details on the degasser in the manual. Waters only said that we could send it to them to be replaced. However, this will cause a massive downtime for our lab. I have read online that there are issues with their life time.

Alternatively, is it possible to run the system without the degasser and degas our solvents manually?

Thanks for any advice!
In the "old days" before vacuum degassers were invented, we would filter through a Millipore membrane into a flask, using vacuum, to de-gas the mobile phases.

Early HP systems like 1084B used stirring/heating and some vacuum to de-gas.

I believe some folks used ultrasonic baths to de-gas too.

Will Waters send a loaner module so you could use and also have a box to send the unit back for the bench repair? Agilent did this, at least while I was working.

Or possibly buy a less expensive aftermarket de-gassing unit; we had several of those.
Sorry to say that this is not something that you can repair yourself. In order to achieve reliable and reproducible results, you need a working degasser. That is what helps provide a stable baseline and good %rsd. The degasser's vacuum chamber, lines, vac pump and PCB all need to be tested to find out what is wrong with it. Normal lifetimes are around 4-5 years. It is possible that one or more vacuum chambers are damaged, the vac pump is worn out and/or the tubing is contaminated. Normal use, esp after 3-5 years also introduces internal contamination to the vacuum system (from the internal parts breaking down from age and also exposure to the chemicals) which enters the HPLC flow path. This contamination often appears as ghost peaks in the system. Now Waters can replace the degasser for about $5K or $6K (USD), but an alternative is to use our company, Chiralizer Services, LLC to have the degasser professionally tested and serviced. We have been servicing them since the 1990's for manufacturers and end users. The typical Waters BSM or QSM degasser we service costs around $1K, but some are more and some are less. No way to know until after we have tested it. If you would like to learn more, please check out one of these links for more info:
    https://www.hplctools.com/waters_degasser_error_troubleshooting.htm or
      http://www.chiralizer.com/hplc-degasser-repair.html
      Hi,

      We recently had a similar issue. Waters said it could be either be the degasser pump, or the board which controls it. They explained to me how to replace one or the other, and when I opened the side cover, I noticed that one of the beige tubes which connect the degasser membrane to the pump was disconnected. I reconnected it, and have had no issue since then. May be worth checking on your side too...
      try to open the degasser and check al connections and tubing first. I fixed one of my Agilent degassers by replacing tubing (got it from aquarium store :)
      Vlad Orlovsky
      HELIX Chromatography
      My opinions might be bias, but I have about 1000 examples to support them. Check our website for new science and applications
      www.helixchrom.com
      1, Check the degasser outlet tube. Is there any blockage? The tube end must not under waste container liquid level.
      2, Remove the right side of the pump. Is there any liquid in the degasser tube.
      3, Plug the line before the junctions of pump and PCB. Is the vacuum test passed?
      6 posts Page 1 of 1

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