Is it possible to remove a EPC from flow shut down procedure on 8890?

Is it possible to remove an EPC from flow shut down procedure of GC 8890? We are using EPC to stabilize sample line pressure at 3bar. When we are connecting new cylinders, we want to be sure that our pressure is slightly over 3 bar, so we set in the EPC to a higher pressure, and we use it somehow as a manometer. But during this procedure the 8890 shuts down the whole instrument due to low pressure. But there is no danger to any columns in the instrument as this EPC is controlling only the pressure of sample line. Is there any option to reprogram 8890 that it will not fall in the shut sown?

Tnak you

Petr

  • Hello  ,

    I’m sorry for the delayed reply to your message.  Do you still need assistance with this? If you do, please take into consideration the notes below. However, if the issue was resolved, could you please share what the resolution was? 

    Do you have a schematic of where the EPC is on the flow path? At this point I have a hard time understanding the role of the EPC. Is it controlling the front channel or the back channel? Based on your description it sounds like it doesn't control any inlet pressure, just the line pressure, but I don't know how that can be the case. Do you have the Part Number for the EPC?

  • Hello,

    Yes, I still need assistance with this as I was not able to find the answer by myself. Sorry as I probably confused you with the EPC abbreviation. It is in fact aux EPC.

    The Auxiliary Pressure Control #1 in the scheme is controlling sample line in four channel valve GC based on 8890. The sample line is over pressured using the aux EPC to 3 bars to achieve better reproducibility. Pressure is programmed during the method to save the consumed sample amount. Unfortunately, this solution is sensitive to pressure in cylinders. As the pressure is lower than 3 bars it will shut down the whole GC. I am looking for a solution if it is possible to remove this Auxiliary Pressure Control #1 from the shutdown procedure. No column is connected to this aux EPC, and it will cause only bad results. The aux EPC is standard three channel EPC option 301.

    Below is the scheme of one channel where you can see the Auxiliary Pressure Control #1 position.

     

  • Hello  ,

    Oh, I was not confused about the EPC abbreviation, I know what it stands for, I was just not sure based on the initial message what its role was in the flowpath.

    So, are you getting this problem only when trying to change cylinders? Or does it happen when the GC is on, whether in idle or acquiring samples too?

    What is the usual pressure at the gas source (cylinders)?

  • Hello CMZainea,

    Yes it happens only when changing cylinders. Because at that moment we use the GC in slightly weird way. The line is connected to 16 position selector autosampler. And when the cylinders are to be changed, pressure on auxEPC 1 is set to 4 bar. During this procedure we use the auxEPC as a manometer. We set the regulator roughtly between 3.2 and 3.5 bar (reading the pressure on GC touch screen). During this procedure, when we are not carefull enough, the GC goes to pressure shut down. So this is the question. Is there any possibility to remove this aux EPC 1 from pressure shutdown procedure?

    Thanks for your help.

  • Hello  ,

    So, there are a couple things to unpack here. First, the 16 position selector autosampler, is that an Agilent ALS or a different model? Based on the description, I assume it's a non-Agilent ALS that requires gas line connection, in which case it would be something I am unfamiliar with.

    In your case, it seems you are using the EPC outside of its intended use. My best suggestion/recommendation before going into an explanation would be to reach out to your local Agilent Team and have them physically check the setup for a more accurate answer. 

     

    That being said, this is what I can share with the information I have so far:

    Generally, if you use an Agilent EPC, you need a Pressure differential of 20 psi (roughly 1.4 bar) between the EPC and whatever comes before that, which in this case seems to be the regulator. In other words, if you need an EPC to provide 4 bar of pressure, you need the regulator to be set at around 5.4 bar or higher. Any lower than that and this is quite possibly why you are getting the shutdown.

    To answer your question in a vacuum, it is possible to remove the Readiness of some hardware components from the panel of the GC but as far as I can tell, you cannot do that for EPCs, only PCMs. Even if you could, I doubt it would solve your issue, as you would need to resolve the cause of the shutdown regardless. To explore the Readiness option, you can go to page 183 in the manual below. 

    Operation Manual (agilent.com)

     

    Again, the approach I recommend is to reach out to your local Agilent Team for a more accurate assessment and solution.

  • Hello,

    thank you for your answer. I do not need to remove it from readiness, but from the shut down procedure. I know I am using the EPC outside of its original purpose (to control flow in analytical columns).

    I first contacted our local Agilent Team, but they did not know the answer as well, so I tried to reach someone on the forum.

    Based on your answer it seems that one cannot remove any EPC from flow shut down procedure as I undestand it corectly. Or at least nobody knows how to do it.

    Anyway thank you for your help. I know that we are using the Agilent 8890 right at or already behind its edge.

    Petr from Wasson-ECE 

  • Hello  ,

    The EPC needs to achieve the needed pressure, and if it does not, it will shut down. It is a safety feature that cannot be turned off.

    No worries, sorry I could not be of more help on this one.

    Calin

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