Disabling "Pressure out of range" error

Oftentimes I find I have “Pressure out of range in x tip”, even when pipetting in labware and my tips aren’t touching anything except liquid. Is there any way to just plain disable this error in fluentcontrol that anyone knows about?

I really just want to ignore this error and “pipette anyway” but that’s not an option with automatic error handling that I can see

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First question, is your labware well defined in the software?

Second, are your 8 channels level? I have found that sometimes they are not level so I teach with the channel that is lowest to avoid pinching.

Third, is it one specific liquid class or many?

Fourth, is it beads?

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Hey Luis!

  1. Yeah everything is well defined,

  2. The channels are level (they just passed maintenance)

  3. It’s a specific liquid class when I go to Z_Max+2. Really doesn’t look like the tips are even remotely touching the botton of the wellplate

  4. No beads :slight_smile:

I’m really just looking to turn off the error, or at least change the pressure range it comes up with

Asking so future Googlers check those things first!

Also what maintenance step checks that the channels are aligned on a Tecan? I’ve had the FAE’s butcher their Fluent Setup testing so many times.

With that said,

  1. There are pressure settings you can adjust in the microscript to raise the tolerance (great for any work involving sticky beads)
  2. Sometimes the default aspirate/dispense speeds are just too damn fast! You can slow these down a bit to minimize pressure errors. You can adjust this in the microscript too.
  3. You can wrap your pipetting logic in a try - catch block with On Error Go To and then filter the error you want to act on and have the system always auto-select a specific option with On System Prompt. You can then also ask it to report to the error in the log or audit trail so you know what messed up.

I would analyze your microscript of your liquid class since there could be something that you can do at that level without having to change your coding logic

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Hey Luis, thanks for your response, really great you’re thinking about future googlers (oh by the way, hello from the past future googlers)

Do you know what those pressure settings are called? I thought they existed too but I can’t seem to find them

Also good idea with the on system prompt message, but the only options with Out of Pressure aren’t quite what I want. There’s no “just do what you were going to do anyway, forget about the pressure” option, from memory they either:
-deactivate the tip,
-dispense the liquid back and do nothing,
-or try again with another tip

Also what maintenance step checks that the channels are aligned on a Tecan? I’ve had the FAE’s butcher their Fluent Setup testing so many times.

EDIT (I forgot to answer): Field Service Technicians have a machined segment with a lot of holes in it that they fix to your machine. They then fix metal tips to your FCA and their software goes through movements to check if your FCA is “in spec” and if your z heights are close enough to each other

I forgot to mention LLD Error Handling Command which gives you a few options including “Liquid Class Defaults”, I’m not sure what that means…

Yes with pressure out of range errors I usually Retry with New Tip but I can see how that’s not an option for some.

The variables are upperPressureLimit and lowerPressureLimit. You can see what you can control in the Variables tab.

If you change it to 1000, make sure you change the lower limit to -1000.

Also you can set them in the formula or at the top of the microscript

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With that said, if this is the ONLY liquid class that is acting up… you may want to do a deep dive/follow up to ensure that the pipetting actions are performing as you expect. I’ve seen where a perfectly solid liquid class started to fail because the original engineers weren’t thorough at all with how the tip behaved so while we could modify pressure variables, it ended up hiding the problem at the cost of cretaing hardware errors.

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Thanks for the detailed response Luis

The variables are upperPressureLimit and lowerPressureLimit. You can see what you can control in the Variables tab.

Do you know what the units for pressure limits are? It seems to want me to input a unit when adding it into the formula tab

Otherwise I’ll just throw it into the microscript tab

With that said, if this is the ONLY liquid class that is acting up…

That’s a good point, but I cannot for the life of me figure it out, because it seems fairly random when it shows up. I’ll keep investigating but changing the pressure limits seems to be a good bandaid fix!

I would set it at the microscript level for now and see if that makes a difference.

Hail Mary option (and this is the convo nobody likes) you could create a fresh version of that liquid class with the exact same parameters and data. I don’t know your system history but in the past I’ve had problems with liquid classes and labware made in older versions of Fluent Control being used on newer versions of the software.

At some point I decided to not only standardize the labware across methods and workflows but also recreate it in the most current versions of the software we were using in the lab. The downside to being one of the earliest adopters I suppose.

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As another note, I’ve seen POOR (pressure out of range) errors on LCs that mix if there isn’t enough delay between asp/disp or if the mix occurs too close to Z_max with higher mixing speeds - typically in channels 1,2 or 7,8 on a LiHa. The Fluent is sometimes too smart for it’s own good.

In these cases, up the delay time momentarily to allow turbulence time to settle, or apply a pattern like aspirate near Z_max and disp near Z_liquid or vice versa. I’d personally avoid extending the pressure ranges if the POOR error isn’t the direct result of clotting or pinning of the tips. And one last thought: possibly replace the inline filters just in case.


Totally, would advise against modifying the pressure generally but if you need the system running while investigating… it’s an option.

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Ah thank you @evwolfson ! I am indeed mixing here, I’ll put in some days, give it a shot and report back

Is the error step is a mixing step, for sure slow down the speeds. The speeds for the default mix values are too fast.

Hey @luisvillaautomata Luis

No it’s not an actual “mix” command, since it’s a worklist where I need to use the same tip to mix / transfer / mix again, I just have mixing within the single liquid class I assign the worklist.

The lowerPressureLimit and upperPressureLimit did the trick. I noticed in their default water_mix command they actually even change it to -1000 and 1000 respectively.

Also @evwolfson I put in delays as well, that might have also fixed it, I didn’t test them individually

Thank you both for your help!

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