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Problems reinstalling the analytical head on a Agilent HP1200 series autosampler after replacing the metering seal

Question asked by soccerdad on Feb 12, 2018
Latest reply on Feb 28, 2018 by soccerdad

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Hi everyone.

Not sure if anyone else has come across this issue. We took off the analytical head for the first time to replace the metering seal. It was difficult to unscrew fixing screws especially the left one but they did come off eventually. The metering seal was replaced without incident but now we can't fix the analytical head back in place. The left hand side screw will not fix in place, almost like it is not long enough to hold the head in place. We did make sure that we ran the appropriate 'Change piston' function in the Agilent software beforehand so that the sampling unit was in the correct position before removal of the analytical head.

We have placed a service call for this problem but in the meantime I am wondering if I missed anything. I couldn't find any videos or guides how to do this other than the basic instructions so it seems to me as though it shouldn't be complicated

Thanks

Kevin

soccerdad Feb 28, 2018 10:29 AM

Correct Answer

Just to bring everyone up to date

As a result of the service call, the whole casing to which the analytical head is fixed was replaced. There was no problem found with the metal ball or the position of the analytical head. The conclusion was that the threads were sufficiently stripped for the left side such that the fixing screw would not hold.

Not a great outcome but at least things are working now

Kevin

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jhagel

Feb 13, 2018 5:00 AM

Hi Kevin,

Here is the link to the older LC maintenance videos which includes the metering head replacement: http://www.chem.agilent.com/cag/cabu/lcvideoindex.asp

It is located under Well-plate Sampler & Micro Well-plate Sampler and Metering Seal and Plunger.

Once you tell the software or handheld to change piston, the metering plunger should be flush. Could you send a picture of the drive without the metering head? You are correct that it should be that simple.

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soccerdad @ jhagel on Feb 13, 2018 9:29 AM

Hi Jhagel,

Thanks for responding.

I have attached a photo of the drive. I did look at the video and didn't see anything obviously wrong with what we were doing

Kevin

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jhagel

@ soccerdad on Feb 13, 2018 11:22 AM

Thank you for posting the picture- from here it looks ok and seems flush....

How about a picture of the metering head itself? from the side?

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soccerdad @ jhagel on Feb 13, 2018 11:54 AM

Here are an assortment of views

Yours

Kevin

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jhagel

@ soccerdad on Feb 13, 2018 12:00 PM

Looks perfect- and if you put the screws in the extend far enough? I'm glad someone is going on-site. Possibly a bad fitting?

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soccerdad @ jhagel on Feb 13, 2018 12:08 PM

Thanks for taking a look at this. It was strange that it held fine until the first time we took it off. I will keep everyone posted with the progress and eventual solution

Kevin

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spacefish

Feb 28, 2018 8:35 AM

Probably the position of the motor is too far out so the backplate of the piston is in the way before the head reaches the casing..

You might be able to drive the motor back with the "Maintenance Positions" tool in Lab Advisor. Get the latest version here: http://labadvisor.pl29.agilent.com/latest

The metal ball you are seing in the drive photo is sitting on top of a spindle which is connected to a motor.

This metal ball presses at the backplate of the saphire piston which is pushed against the ball via the spring seen in your second last photo.. The piston is visible though the spring..

You might also be able to press the head against the drive so the backplate is pushed into the head / piston moves into the head and the spring compresses and you are able to put in the screws while still pressing the head in against the spring..

You can press in the backplate by hand against the spring tension, it´s not that hard, but be careful as applying any off-axis force might break the saphire piston.

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soccerdad @ spacefish on Feb 28, 2018 10:29 AM

Just to bring everyone up to date

Not a great outcome but at least things are working now

Kevin

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8 Replies

jhagel Feb 13, 2018 5:00 AM
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Correct Answer
Hi Kevin,
Here is the link to the older LC maintenance videos which includes the metering head replacement: http://www.chem.agilent.com/cag/cabu/lcvideoindex.asp
It is located under Well-plate Sampler & Micro Well-plate Sampler and Metering Seal and Plunger.
Once you tell the software or handheld to change piston, the metering plunger should be flush. Could you send a picture of the drive without the metering head? You are correct that it should be that simple.
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- soccerdad @ jhagel on Feb 13, 2018 9:29 AM
  Mark Correct
  Correct Answer
  Hi Jhagel,
  Thanks for responding.
  I have attached a photo of the drive. I did look at the video and didn't see anything obviously wrong with what we were doing
  Kevin
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  - jhagel @ soccerdad on Feb 13, 2018 11:22 AM
    Mark Correct
    Correct Answer
    Thank you for posting the picture- from here it looks ok and seems flush....
    How about a picture of the metering head itself? from the side?
    Like • Show 0 Likes0
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    - soccerdad @ jhagel on Feb 13, 2018 11:54 AM
      Mark Correct
      Correct Answer
      Here are an assortment of views
      
      Yours
      Kevin
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      - jhagel @ soccerdad on Feb 13, 2018 12:00 PM
        Mark Correct
        Correct Answer
        Looks perfect- and if you put the screws in the extend far enough? I'm glad someone is going on-site. Possibly a bad fitting?
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        soccerdad @ jhagel on Feb 13, 2018 12:08 PM
        Mark Correct
        Correct Answer
        Thanks for taking a look at this. It was strange that it held fine until the first time we took it off. I will keep everyone posted with the progress and eventual solution
        Kevin
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spacefish Feb 28, 2018 8:35 AM
Mark Correct
Correct Answer
Probably the position of the motor is too far out so the backplate of the piston is in the way before the head reaches the casing..

You might be able to drive the motor back with the "Maintenance Positions" tool in Lab Advisor. Get the latest version here: http://labadvisor.pl29.agilent.com/latest

The metal ball you are seing in the drive photo is sitting on top of a spindle which is connected to a motor.

This metal ball presses at the backplate of the saphire piston which is pushed against the ball via the spring seen in your second last photo.. The piston is visible though the spring..

You might also be able to press the head against the drive so the backplate is pushed into the head / piston moves into the head and the spring compresses and you are able to put in the screws while still pressing the head in against the spring..

You can press in the backplate by hand against the spring tension, it´s not that hard, but be careful as applying any off-axis force might break the saphire piston.
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- soccerdad @ spacefish on Feb 28, 2018 10:29 AM
  Unmark Correct
  Correct Answer
  Just to bring everyone up to date
  As a result of the service call, the whole casing to which the analytical head is fixed was replaced. There was no problem found with the metal ball or the position of the analytical head. The conclusion was that the threads were sufficiently stripped for the left side such that the fixing screw would not hold.
  Not a great outcome but at least things are working now
  Kevin
  Like • Show 1 Like1
  Actions

Problems reinstalling the analytical head on a Agilent HP1200 series autosampler after replacing the metering seal

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