Agilent 1100 HPLC Degasser

[adgarret]

Hello all,

I have an Agilent 1100 HPLC and I'm pretty sure it has a malfunctioning degasser (light stays yellow for a few minutes then shuts off). It has new vacuum tubes and all of the connections look fine, so I did the troubleshooting procedures in the manual. The pressure reading when isolating the pump was about 920 mV (definitely above 500 mV). I tried the other procedures for the solenoid valve and the vacuum chamber and they both gave readings of around 900 mV as well. If I've done all of this is it guaranteed that the problem is with the vacuum pump? I'm definitely a "guy with wrenches" so I just want to make sure before purchasing a new vacuum pump. Has anyone else had this problem? Any help is appreciated. Thanks!

[Atheln]

Hello,
Assuming that you have a G1322A, let me say something: when you turn on the module, the pump starts working and the status light is yellow; after some minutes, the pump stops and the light turns off. Is that what you see? If "yes", the degasser is OK and those minutes are the time needed to reach the limit pressure; after that, the pump works only for short periods maintaining the vacuum. If "no", if the lamp turns red, you do have a problem. Please, send me further details so I know if I understood your question and I can give you more help.
Regards.

[Consumer Products Guy]

I've fixed 1050 degassers with vacuum tubing from my friendly auto parts store.

[adgarret]

Yes, I get the red light after about 8 minutes and the whole thing stops working. During the 8 minute time period I run the tests that I posted earlier getting a pressure reading around 920 mV when isolating the vacuum pump. The manual says it should be below 500 mV for a good working pump. Any advice is appreciated.

As I mentioned earlier the vacuum tubes are new.

[coffee bean]

Actually you could have a problem in your vacuum chamber as well. If you have never opened it, I guess it is most likely to be the vacuum pump though.

[HPLCCONSULT]

I repair vacuum degassing units on a regular basis and am very familiar with the two Agilent models so have a few comments.

*Basically, if the red LED comes on, you have a problem. If it does not come on, then the unit is operating to the manufacturer's specification.

If as you say you have correctly bypassed all of the internal tubing and connections to isolate the vacuum pump and sensor in the G1322A degassing module, then YES the vacuum pump should be replaced. A reading of 900 plus mv's must turn the RED LED on at this point. The chambers and solenoid are not the problem. You should be able to obtain a very low reading (below 610 mv) with just the pump connected to the pressure sensor (assuming the sensor is working correctly). The degasser goes through a series of error modes. The red LED will come on when the system is unable to obtain a vacuum reading below 800 mv during the initial phase. The yellow LED goes OFF when the value drops below 800 mv's (when you first turn it on, it is around 3.5 Volts). I won't go into the other error modes as your system appears to have failed at the first stage. A red LED always means the on-board diagnostics have detected a serious failure. If no red LED is shown (after at least 30 minutes of operation), then the unit is fine. The on-board diagnostics of the degassing modules are rather good. Use the AUX output to monitor the voltage.

*One other thing you can do is to put the system in 'continuous mode' operation (SW1 ON). This makes the vac pump run 100%. Check the output under these conditions to see how low it can go and hold it there (in mv's). In real life, the solenoid normally switches the pump in-line when the vacuum rises above ~610 mv's, but since the pump is 'ON' 100%, the solenoid valve just stays open and the pump pulls all of the time. This mode provides maximum degassing performance so if your degassing unit works fine in this mode, then the pump is probably weak or you have a leak somewhere else. If it runs w/o a red LED, you can use the system in this mode until something finally fails.

How old is your degassing unit ? They will all break down at some point and need replacement parts. We often see units which have been used daily have one part fail after 5-10 years of use.

[adgarret]

Wow thanks for all of the info. The unit is about 10 years old, so I guess it was about time the pump failed. I'll post another reply once I've fixed it.

[bam_pk]

Dear HPLCCONSULT,

thank you so far for all your helpful information.
Our pump only reaches about 790 mV, so the light turns red after 8 minutes. My manual says pressure has to be under 600 mV to work correctly. So in my case I also think the pump has to be replaced (Agilent 1100 series). Even by putting vacuum directly on sensor it only reaches 780 mV.

But until the new pump will arrive, I want the pump to work in 'continuous mode' (SW1 ON) as you described. But although I switched SW1, the degasser turns red after some time, but it takes longer than 8 min this time!!

Any idea why there is an error again?

There is a second switch (SW2). What happens if I switch this one too?

Thanks in advance!

[AIM]

I always need 1100 degassers repaired. How much do you charge?

[Multidimensional]

Alex: That post was 6 years old!

contact Chiralizer Services for a Diagnostic Evaluation quote.

http://www.chiralizer.com/hplc-degasser-repair.html