Questrion on Degasser vacuum error in UPLC

[littlepumpkin]

Does anyone has problem with degasser error in UPLC? We have an Acquity UPLC and the seal wash solvent bottle was run dry by mistake. Now we keep seeing degasser vacuum HW error. We are trying to rescue it. However, I've tried to fill the line before the pump with solvent, and tried to pull air out from the outlet for more than 4 hours. Still there are bubbles coming out with the solvent. Does anyone have an idea how to fix the problem? Thank you very much in advance!!!

[dblux_]

Degasser replacement probably necessary.

[littlepumpkin]

I see. Thank you very much!

[dblux_]

I don't know details of your instrument configuration but in my opinion lack of seal wash solvent shouldn't have any influence on degasser, but rather on premature fail of piston seal.

You may check whether degasser pump switches on periodically. If it works continously, it indicates leak.

Hope it's not the case because degassers are expensive.

[littlepumpkin]

Thanks! But how can I tell whether degasser pump is on or not? Is there an indicator as light or sound?

Thanks!!

I don't know details of your instrument configuration but in my opinion lack of seal wash solvent shouldn't have any influence on degasser, but rather on premature fail of piston seal.

You may check whether degasser pump switches on periodically. If it works continously, it indicates leak.

Hope it's not the case because degassers are expensive.

[dblux_]

Thanks! But how can I tell whether degasser pump is on or not? Is there an indicator as light or sound?

On the basis of my experience with Dionex HPLC low pressure gradient pump:

degasser is built into pump module, and it switches on to achieve vacuum then it switches off, after period of time it switches on again. You simply hear that discrete sound of degaser piston moving periodically. No other indicators are available.

Maybe there is troubleshooting guide in your documentation (check degaser fails or similar topics).

[Bull76]

Hi,

The acquity degasser pump is the same as on the Alliance. It initially runs at about 400rpm's until vacuum reached or if it doesn't then the error occurs and the pump is shutdown. It is always on, but when the vacuum level is reached then it rotates at about 40 rpm's.
There could be an issue with the degasser chambers especially if your getting air in you solvent lines. I'm assuming you have wet primed the solvent lines with Methanol to aid in removing the air. Do this on all lines for ten minutes. Is there any liquid coming out of the vent for the degasser?

Regards,
Bull76.

[littlepumpkin]

There's no liquid coming out of the vent for the degasser. Only liquid came out once in a while from the seal wash leak tube (not the seal wash vent line). I haven't primed all lines with methanol. I guess LC-MS grade methanol is needed?

I cannot understand why all of a sudden we have this serious problem. So the seal wash is completely independent from the solvent lines? Is it possible that due to the seal wash is actually pumping air into the solvent pump, it also introduced air into the solvents?

Hi,

The acquity degasser pump is the same as on the Alliance. It initially runs at about 400rpm's until vacuum reached or if it doesn't then the error occurs and the pump is shutdown. It is always on, but when the vacuum level is reached then it rotates at about 40 rpm's.
There could be an issue with the degasser chambers especially if your getting air in you solvent lines. I'm assuming you have wet primed the solvent lines with Methanol to aid in removing the air. Do this on all lines for ten minutes. Is there any liquid coming out of the vent for the degasser?

Regards,
Bull76.

[aceto_81]

For the UPLC, you have a lot of vacuumchambers: for each solvent line (A1, A2, B1, B2), but also for your weak wash, strong wash and seal wash.
Put your sealwash in 100% methanol, and prime your seal wash with this.
What I do is unscrew the fitting at the degasser until all the air is out of the sealwash line and is dripping methanol, before priming, this is already 8 ml air which doesn't have to be degassed.
Now let prime your seal wash, and afterwards check if the problem is still there, normally it should be away.
If it's not, please call Waters.

For the 100% methanol doesn't matter if it's MS quality or not, you will flush this afterwards with your own mixture of seal wash, in our case we use 90% water / 10% methanol.

Good luck

Ace

[Bull76]

If the seal wash line still has air in it then you need to connect a syringe to the seal wash line and pull the solvent through the system. Firstly you need to start the prime seal wash function, Disconnect the seal wash line from one of the pump heads and connect the syringe and hypo needle and pull the solvent through.
Then allow about 20ml of liquid into the syringe, then re-connect the tubing to the pumphead. That should be the seal wash line primed.
For an acquity BSM then degasser chamber is one unit and needs to be replaced as one unit. It isn't serviceable. For a QSM then the degasser chambers are all seperate. But I guess you have a BSM system.
If the pump seals are damaged then you would see an issue with pressure. Shouldnt affect the Degasser pump though. But if the seal wash line has air then yes it would affect the degasser as it wouldn't be able to remove all the air. It's function is to maintain the removal of desolvated gases in your mobile phase solvent which has been sonicated/filtered.
Waters recommends priming all lines in methanol to aid in the removal of trapped air, they do this and use methanol for all diagnostic tests to be carried ut on the Acquity system.

Hope this helps it is a bit long winded.

[dblux_]

For the UPLC, you have a lot of vacuumchambers: for each solvent line (A1, A2, B1, B2), but also for your weak wash, strong wash and seal wash.
...

I wasn't aware that in Waters instruments seal wash liquid goes through degasser (in fact I can't guess sensible explanation for this design).
Knowing that, I have to revise my former opinion that seal wash have no influence on degasser.

Hope it is only filled up with air, not damaged.

Good luck from me as well.

[DR]

For future reference - it is never a good idea to try to pull anything into a degasser (unless you know otherwise, for certain that yours can deal with it. There are some old units that can handle this, they typically have a high internal volume - 10mL or more).

Many modern degassers can be easily ruined by having a vacuum applied to their outlets.

[aceto_81]

For future reference - it is never a good idea to try to pull anything into a degasser (unless you know otherwise, for certain that yours can deal with it. There are some old units that can handle this, they typically have a high internal volume - 10mL or more).

Many modern degassers can be easily ruined by having a vacuum applied to their outlets.

I think the idea about pulling the solvent through the seal wash line is understandable:
For the Waters Alliance it is a common practice to pull the sealwash through the line, but here the seal wash isn't running through the degasser.


Ace

[dblux_]

What's the point of degassing seal wash liquid ?

"For the UPLC, you have a lot of vacuumchambers: for each solvent line (A1, A2, B1, B2), but also for your weak wash, strong wash and seal wash."

[AA]

The seal wash does NOT pass through the degasser on Acquity systems. Its a 6 channel degasser A1,A2,B1,B2, weak needle wash and strong needle wash that pass through it.