Chromatography Forum

Hello Everyone,

We just received a used Agilent 1100 HPLC and I'm trying to get it to work. So far I have completely disassembled the pump and cleaned all parts. There are no clogs in the lines or any of the pump seals and inlet/outlet valve. The problem I'm running into is this...

I am unable to draw up any solvent, and when I prime the pump with a syringe the pump begins to pump the solvent back and forth and the active inlet valve begins to leak. The purge valve is open and I can't find any clogs in any lines. Why is the solvent not moving forward and how do I fix the active valve from leaking? I should also note that the pressure never goes above 1 bar according to the chemstation screen.

THANKS,
Ben

One possibility is that the electrical connection to the valve is disconnected or broken.

Second possibility is that the valve "innards" are damaged/dirty.

Agilent has a series of videos on servicing 1100 pumps that might help:
http://www.chem.agilent.com/en-US/Suppo ... ideos.aspx

Could it be a bad check-valve? That's what it sounds like to me, but I'm sure it could be any other number of things. If you haven't already tried that, maybe purchase a new set and see if it improves things?

Another likely problem is that the AIV is just not tightened enough against the pump head. It is hard to do, and you need the special, flat 14 mm wrench. But make sure it is tight before you go any further.

Thanks for the replies. So far I have cleaned the AIV, Pump, Check-Valve, etc and made sure everything was free of debris. I then reassembled the parts and had the same problem and noticed a new problem. It seems that when I switch all four solvents on the C and D resevoirs get drawn to the pump, but the A and B resevoirs get PUMPED OUT. They go in the opposite direction AND the AIV still leaks from around the edges. I even used a syringe full of MeOH directly in to the AIV while the pump was running and it still leaked. Does anyone have any suggestions? Do I need to replace the AIV and hope that's the problem or could something be wrong with the MCGV???? Thanks in advance.

Ben M

I'd start by bypassing the multi-channel valve and using one channel directly into the active inlet valve using Agilent adapter #0100-1847 (this should have been supplied with your system). That way you can first determine whether your pump is OK; if it is, then you can investigate the multi-channel valve. So first you need to isolate the problem.

I don't fully understand "when I switch all four solvents on the C and D resevoirs get drawn to the pump, but the A and B resevoirs get PUMPED OUT. They go in the opposite direction "

Basically I set each line (A,B,C,D) to 25% at a flow rate of 2 ml/min. What I observe are the bubbles/solvent in the C and D lines are traveling toward the pump, while the bubble/solvent in the A and B lines are traveling toward the reservoirs. Also the solvent from the line from the MCGV to the AIV goes back and forth. When one piston is drawing in the solvent, it (solvent) moves toward the AIV, but when the other piston is pushing the solvent moves the other direction. Does that make any sense?????

Ben M

I would manually purge the lines. Disconnect each from the multi-channel valve, and use a 10 ml or 20 ml syringe with adapter to repeatedly pull the solvent through (actually, it should leak/drip out on its own if filled with liquid, due to gravity, as the solvent reservoirs are higher). Then re-attach and go to the next one. As to your purging with 25% each at 2 ml/minute, I'd purge each separately at 5 ml/min for 5 minutes, then go to the next channel. And make sure your solvent reservoir inlet frits are clean and not partially plugged.

OK so I manually purged the lines and tightened the AIV and started pumping. The leaking from the AIV was reduced and the solvent seemed to get pumped, but I noticed that the pressure read 1 bar no matter how fast or slow I was pumping. What would cause the pressure not to change while the pump is pumping? I'm using Chemstation FYI.

Ben M

OK so I manually purged the lines and tightened the AIV and started pumping. The leaking from the AIV was reduced and the solvent seemed to get pumped, but I noticed that the pressure read 1 bar no matter how fast or slow I was pumping. What would cause the pressure not to change while the pump is pumping? I'm using Chemstation FYI.

Ben M

My guess is that there's a pressure regulator somewhere on the system that's set to 1kpsi. If not a pressure regulator, than something acting as a pressure regulator.

Are you just running the pumps, or are you running the pumps into an autosampler/detector/whatever? You could try disconnecting the pumps from anything else that's in-line and see if that results in the pressure becoming dependent upon the flowrate.

Are you sure that your purge valve is closed? That is the most likely reason for low pressure, assuming that you are getting some flow from the pump. Your purge valve may need replacement. Verify whether flow is coming out of the waste line or the column port.

Also, "flushing" the AIV is usually not necessary. There is really nothing to flush. It is an electronic valve with a plug in cartridge. It is possible the cartridge may need replacement as well. You should not have leaking around the AIV under any conditions. The cartridge may be damaged or not installed correctly, but you must fix this problem first.

After reading your post again, I have to ask an additional question.

Where is the AIV leaking? Is it at the fitting where it connects into the pump head, or the plastic fitting where the solvent enters from the mixing valve?

Sounds like you may have multiple problems.

I have found that simply "cleaning" the AIV or the outlet ball valve do very little to repair them. I would simply replace both.

The solvent line problem sounds interesting. I'd completely remove the GPV from the flow to make sure the pump is working properly, then it will be easier to tell if your GPV is faulty. You can use a union to connect the GPV inlet line directly to the GPV outlet line, but you obviously can only check one line at a time.

And sometimes the AIV gold seal (that acts as a gasket) needs to be replaced, as a bad one can cause leaks.

Everyone thanks for your replies. To start...

The AVI appears to leak from the square black plastic gasket(?). What's confusing to me is that there is absolutely ZERO change in pressure once I increase the flow rate. All that happens is the solvent leaks more from the AVI and the waste lines flow increases a little. So I know that solvent is getting pumped through to the waste line, but in doing so there is no change in pressure and the AVI leaks from the square black plastic gasket. I performed a pressure test in Chemstation but it failed. I think my next course of action will be to buy a new AVI and go from there???????

Ben M