Agilent 6890 High Pressure/Low Flow - Shutoff error

I am working with an Agilent 6890, Splitless Inlet, and am having problems with the pressure maxing out and cutting off flow. The Front Inlet Low Flow Shutoff notice shows and the GC stops running. I have checked the septum/septum nut, replaced the liner, checked the gold seal, and clipped the column, none of these things fixed the problem. We cannot run the instrument for more than 2-3 minutes before it shuts off.

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0 james_jenkins over 5 years ago

Hi b_haas,
When you say pressure is maxing out? Is it going beyond the set point? Can you supply parameters such as set point , total flow, etc? The last one I saw over pressure had the gold seal installed upside down.
Regards
James
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0 b_haas over 5 years ago in reply to james_jenkins

Hi James,

The initial pressure and flow are set at 7.8. As soon as the run is started, the pressure goes as high as the supply is set to, within a half a minute. When it reaches that point, the flow lowers to 2.3 and then zero. Then the instrument says #4 Front Inlet Flow Shutdown.
We have not changed the gold seal recently and it has ran fine for the last 2 years, so I can't imagine the gold seal could be the issue.

Sincerely,
Brenda
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0 b_haas over 5 years ago in reply to james_jenkins

Hi James,

The initial pressure and flow are set at 7.8. As soon as the run is started, the pressure goes as high as the supply is set to, within a half a minute. When it reaches that point, the flow lowers to 2.3 and then zero. Then the instrument says #4 Front Inlet Flow Shutdown.
We have not changed the gold seal recently and it has ran fine for the last 2 years, so I can't imagine the gold seal could be the issue.

Sincerely,
Brenda
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0 james_jenkins over 5 years ago in reply to b_haas

Hi Brenda,
Whats the total flow setting on the inlet set at? If the total flow is set high because of a high split can be one reason. I suspect this is more of a hardware fault like a blocked split line or a split valve problem.

Shutdown #4
This message indicates the inlet failed to reach its flow setpoint in the allotted time or cannot maintain its flow setpoint. When you are operating in flow-control mode, the inlet has 2 minutes to reach the setpoint before shutdown. The instrument will be not ready until the problem is corrected and the inlet reaches the flow setpoint.

Regards
James
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0 james_jenkins over 5 years ago in reply to b_haas

Hi Brenda,
I would suggest contacting service at this point, you have an issue somewhere in the inlet pneumatic control that would be better addressed with a service visit.
Regards
James
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0 b_haas over 5 years ago in reply to james_jenkins

James,

The inlet purge flow is set at 1.8, with the total flow fluctuating around 1.3 - 1.4. This is a splitless system, with only the front inlet installed.

Sincerely,
Brenda
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0 b_haas over 5 years ago in reply to james_jenkins

We have sent the instrument in for service. I will give an update on what the repair was when I have more information. Thanks for all the help.
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