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avatar: milhabia
milhabia
2 posts
Replied to milhabia's post on June 16th, 2010
We have several Agilent 1200 systems equipped with micro degassers. Over the last couple years, many of them have started leaking out the front waste port. I know not to put the flow over 2.5 mL/min with the degasser inline. Why do we keep experiencing leaks? Something must keep affecting the vacuum chamber(s). The strongest solvent we are pumping through the system is IPA. After replacing pump seals, the manual instructs to perform a seal wear in procedure. It also instructs to replumb the lines to exclude the degasser. If people are leaving the microdegasser inline, could this be the reason for the leaks? I ask this because out of all the times I remember them leaking, it has always been IPA. The only time straight IPA is installed on our instruments is during preventative maintenance or during the seal wear in procedure.
avatar: bisnettrj2
bisnettrj2
1 posts
Replied to milhabia's post on June 19th, 2010
I recently had a leaking G1322 degasser. I took it apart and realized the leak was simply at the output of one of the degasser chambers - it had seemingly just come loose. I re-tightened it, and the leak was gone. No more leaks, so it would do you good to open up the degasser and figure out exactly where it is leaking. Might save you a couple thousand dollars having Agilent do a bench repair!
avatar: LabWrenchManager
LabWrenchManager
610 posts
Replied to milhabia's post on June 21st, 2010
I know with the degassers on the 1100's, when our maintenance company switched the factory vacuum chambers for the micro ones we popped several almost immediately because analysts were used to putting a syringe on the pump output to prime the system if it ran dry, this apparently puts too much pressure on the chamber and it pops. We eventually got people to prime the system by sucking solvent from the reservoir to the input side of the degasser, then opening the connection at the mixer and allowing gravity to prime the degasser. We never used IPA as a solvent though (horrible viscosity)

This post was made on behalf of Paul Hurley
avatar: LabWrenchManager
LabWrenchManager
610 posts
Replied to milhabia's post on June 21st, 2010
I do not know why you are concerned with pump maintenance issues if you have a degasser leak. If you are doing everything correctly and not abusing the system, then seal wear in should not be causing your problem.

Both degasser models can handle flows up to 10.000 ml/min, but will of course do a better job of degassing at lower flow rates. The leak is most likely caused by one of the two vacuum chambers failing. The vacuum chambers do fail from time to time. Leaks are not uncommon on either the standard degasser (G1322) or the micro-degasser (G1379). Often they are caused by using strong acids or concentrated buffers in the mobile phase. I have also seen them fail for no apparent reason after five or ten years of use too (all brands, not just Agilent/HP). When you have a visible leak outside of the degasser that is NOT due to a bad or loose low pressure ¼” inlet/outlet fitting (most leaks are from a loose fitting), then you probably need to replace the main vacuum chamber in the case of the G1322 or maybe just one chamber for the G1379 unit. *Open it up to confirm the location of the leak.

The pump seal break-in procedure can be done with any viscous organic solvent (yes, IPA is a good choice, but not the only one) that does not attack stainless steel. It should have zero effect on the degasser. When you “seat” new seals in the pump head, you pump up the head with the outlet PLUGGED to force the seals into the head under the maximum pressure (~ 400 or 600 bars). This only takes a few minutes and the flow rate is nearly stationary while this is happening (a liquid is being compressed so not much flow). The pump inlet (low pressure side) is effectively near atmospheric pressure while this happens so it will not make much difference if the degasser is connected during this time. *If you are using the alternate method of 'seal wear in' described in some of the newer Agilent Pump manuals which utilizes a restriction capillary (5022-2159) connected to the purge valve in place of a plug, then you usually want an unobstructed flow of solvent being directed into the head (by-pass MCG valve and run into AIV right from a bottle. This is done because they recommend you flow solvent through the head for fifteen minutes at 350-400 bars to seat the seals in over time. That method does not use a degasser in line.

My suggestion: Use the original seal wear-in procedure done manually, not through the computer system (system purged and flushed with clean solvent; close prime purge valve; outlet plugged with blanking nut; monitor pressure signal on screen; flow = 1.000 ml/min to 200 bar, when it hits 201 bars then change flow to 0.200 ml/min till it pegs and holds at 400 bars for a few minutes. No disconnecting the degasser or MCG Valve. This is the system that Agilent/HP used for the 1050, 1100 and 1200 pump (all 99% the same) and it works fine today.

This post was made on behalf of William Letter, Sr. Scientist, Consultant & President at CHIRALIZER SERVICES, L.L.C.
avatar: milhabia
milhabia
2 posts
Replied to LabWrenchManager's post on June 21st, 2010
Thanks you for your informative response! I’m not really concerned about pump maintenance issues, however. I was just wondering if the seal wear in procedure could cause a leak in the micro degasser if the micro degasser is left in-line during the procedure (the method utilizing the restriction capillary). The manual instructs to bypass the degasser, and route the flow of IPA directly into the AIV. If this is not done, could this potentially cause a leak in the vacuum chamber? Nearly all the times I’ve seen a leak on a system, it is IPA that leaks out the vacuum pump waste tube. We only use 100% IPA on our systems when the seals need to be changed. Two weeks ago someone in my lab changed pump seals and performed the seal wear in procedure with IPA and a restriction capillary. Immediately after, IPA leaked out of the degasser. I’m not sure if the flow was rerouted to bypass the micro degasser or not. Could this have anything to do with the leak?
avatar: LabWrenchManager
LabWrenchManager
610 posts
Replied to milhabia's post on June 22nd, 2010
Perhaps this will help.

"Could plumbing the degasser in-line during a pump seal seating procedure cause the problem ?" Perhaps.

Under "normal" conditions, most methods rarely utilize such a viscous liquid such as 100 % IPA so do not encounter the problem seen. Typical solvents are of much lower viscosity and lower pressure. If the degassing system has been primed with pure IPA and then switched over to a much lower viscosity solvent after performing a task such as 'seal seating', then yes it could cause the degasser's FITTINGs to reveal a leak (meaning they are probably loose inside) due to the pump being turned ON to flush out the chambers full of a very viscous liquid (IPA). This would be more obvious at higher flow rates (> 0.500 ml/min). I would safely check inside and outside the degasser for any loose fittings or a leak. I would also ask if the problem goes away AFTER the degasser has been purged of all of the IPA. If it still leaks AFTER you have completely purged the 100% IPA from the degasser system, then there is a leak. Remember that the chamber volume is rather large on the G1322A unit (please see my "Hints & Tips" page). Again, please check the fittings first.

If you use the pump seal seating method which includes the restriction capillary and flow for 15 minutes, then do not plumb the degasser inline. It is unnecessary. As mentioned before, I personally do not recommend that method for seating the seals in the pump.

This post was made on behalf of William Letter, Sr. Scientist, Consultant & President at CHIRALIZER SERVICES, L.L.C.