Chromatography Forum

First off, thanks to bull76 for aiding me with this so far, I got the "top sensor too low" message to go away during the seal pack adjustment process for the 717 plus LC Waters autosampler. The calibration was going pretty well until another message showed up, "could not find upper seal". Hopefully, this one isn't problematic, any suggestions on how to get rid of this message? Would really appreciate it.

Hi,

You need to make small adjustments to the sensor assy. You should be able to get a sweet spot and the adjust seals will complete. Time and patience is what it takes.

I see you have about three differnet post's open for the same thing. Maybe worth while just using one post and goinf from there. You have the seals adjusted from a previous post. Carry out a compression check and if that passes, carry out an injection accuracy test or lift test.

Regards,
Bull76

Hi,

You need to make small adjustments to the sensor assy. You should be able to get a sweet spot and the adjust seals will complete. Time and patience is what it takes.

I see you have about three differnet post's open for the same thing. Maybe worth while just using one post and goinf from there. You have the seals adjusted from a previous post. Carry out a compression check and if that passes, carry out an injection accuracy test or lift test.

Regards,
Bull76

I've carried out a compression test and got the message "compression exceeds limit", did some valve tests as outlined by the autosampler manual and all of them seemed to pass. Perhaps I'm using the wrong parameters for the compression test, used 350 psi for a compression parameter, maybe that had something to do with it.

- make sure the system is well purged with degassed MeOH.
- if the seal is not properly found, the compression check will fail.
During this test, the needle is positioned at a seal, all valves are closed and pressure is built up by moving the plunger of the syringe. Then the pressure has to be constant over a certain period. If the plunger has to be moved to much without pressure build up, the observed message is likely.
- is the needle posititioned in the correct way (direction of the needle hole)?

Have you seen the tutorials/SOPs on the Waters homepage (search for "seal pak" maybe "seal pak self service")
-> Installing the Needle and Seal Pak
-> Calibrating the Seal Pak

If you don't have accsess, maybe they will send you a copy by email.

the last time I checked, the hole of the needle was facing left when facing the entire injection platform from the front. I'll take a look at the Waters homepage to see if there's anything that's incrementally useful compared to their online manual as far as installing and calibrating a seal pack goes.

again, the compression check did not pass even though the calibration passed. Albeit with the upper seal at positions of 300+. I've moved the platform down to the point where it says that the "top sensor is too high", then moved it up (perhaps by too many notches) where it now says something along the lines of seal width is too low. I'll have to work my way down by slightly turning the screw once again in hopes of finding a workable spot in between. Thanks for your help thus far, it's been really useful.