Glass(!) Jar Lid Gasket/Seal 1

[Helepolis]

Hi all,

So after giving a shot at the correct sub-forum, with only one quite abstract response, after more than 10 days I figured I'll try a more lively venue to ask.

I have a lab glass beaker (borosilicate 3.3; off-the-shelf product) lets call it the Container, which is intended to be used in a clinical drug delivery device (human clinical trials).
The container will hold a certain amount of an inert aqueous solution, at room temperature and atmospheric pressure at all times.

At certain points of time when the container is used it needs to be hermetically sealed, so that nothing can get into or out of the container, meaning that the sealing solution can be fitted in place and removed as necessary manually.
To seal the container I can only use a press-fit cap (similar to those generic food storage containers, as in the attached image).

I've tried to use regular O-rings (PTFE, Viton, Silicone) but each O-ring had it's issues sealing the container (in a nut shell the PTFE was to stiff and hard, Viton and Silicone on contact with glass just seize in place due to high friction).

I've tried to search for a V-ring or a U-ring that might work (even if it's not what it was originally designed to do), but didn't find anything specific.
The idea for the V-ring or U-ring came after observing the way those food container are sealed with the seal/gasket having one ore more "flanges"/"skirts" (marked with red arrows in the image).

The seal/gasket must be a bio-compatible with certification (otherwise we wont be able to perform the clinical trials).

I'll appreciate any ideas!


Thanks,
SD

 

[TugboatEng]

You need to use a lubricant. I assume grease or paste type lubricants are unacceptable. There are coated (not to be confused with encapsulated) o-rings available.

https://community.parker.com/techno...292/does-parker-offer-ptfe-coating-on-o-rings

 

[Jboggs]

Are you assuming that the glass beaker must remain in its current shape? Based on what you've told us, I would think that some standard off-the-shelf beaker/lid combination would work for you.

 

[Helepolis]

Thanks TugboatEng,

I thought about coated seals, but I can't use anything that can leave residuals in the liquid that's inside the container, they note it in the link you have provided, that the coating may flake off.

I genuinely can't believe that there aren't any available solutions for seals that "work" with glass, meaning they have low coefficient of friction, so it won't stick on to the glass and pliable enough to bridge small tolerances.

 

[EdStainless]

You could go round and just use conventional ground glass seals like they have been doing on labware for 200 years.
If you try to use gaskets, you will need a round container anyway.
And you can't use these mechanically energized ones as the rest of the lid is far from a tight seal.
Link
Link

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[IRstuff]

Hermetic has a certain connotation in various industries; what do you mean by it and under what environmental stresses is it subject to? If it's only to stay relatively secure and not let junk get in, that's different than having to maintain pressure under vacuum.

So, some other things come to mind
> classical glass frit seal, but that requires a round opening
> a rubbery "boot" lid that seals over the outer edge, which could potentially eliminate a lubricant requirement
> the Press-n-Seal plastic wrap, but not reliably reusable

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[BrianE22]

Can you redesign the top and make it a face seal? The glass may not be flat enough. Add a couple of wire U-shaped clips that swing into place below the bottom of the jar to pull the top down tight to the glass.

 

[MintJulep]

https://www.fishersci.com/shop/products/fisherbrand-ultrasonic-units-beakers-lids-2/p-4364474

 

[Helepolis]

Thank you all for the great answers, but I believe I wasn't clear enough about the setup as a whole.

The container and the lid are designed for multiple uses, and are part of an assembly that comes into indirect contact with the patient (clinical trials), meaning it's at least a Class II device (drug delivery).
This means that it has to adhear to specific biocompatibility standards (e.g. several sections of the ISO 10993, and USP 88/87), both in terms of chemical reactions (bio-comp.), cleanliness and sterilization (geometry, bio-comp. and durability) of the materials used.

This implies that there are limitation in terms of materials used (even glass can be of a medical grade, or more specifically the glassware for it's whole manufacturing process), and the geometric features of the items used (to match the desired/available sterilization methods, and cleanliness requirements).

Now for the specifics of the glass container and the lid.

The lid itself is a custom design as it not only seals the glass container and it's liquid content (i.e. an inert aqueous solution), in addition, at some point after the lid is closed, it performs a mechanical action for agitating the liquid inside the glass container.
In addition, the lid has valves, channels and connection points on it for "fluid control" and pressure equalization.
The lid is 3D printed from suitable a bio-comp. resin.

It's important to note, that despite the apparent complexity of the lid, it's highly customizable, meaning that in theory I can adapt to any shape and form of a certain seal.

The glass container has to be from a "medical grade" glassware (borosilicate), and contain at least 800ml of volume.

The sealing action can be done ONLY against the inner wall of the glass container, so a face-sealing isn't an option (I won't go into details why, it's a long story).

The lid has to hermetically seal the glass container and it's contents, meaning that nothing from the ambient environment can interact with the contents.

The seal will work under atmospheric pressure (zero gauge pressure; through a breather valve) and room temperature (25-30 deg C), at all times.
Basically it "just" has to prevent the liquid from spilling around the gap(s) between the lid and the glass container.

It's important to note that when the seal is "engaged", the container and it's contents will be placed in an "horizontal" position until the container is vacated of it's contents through the valves and connection points on the lid, regardless if the liquid is agitated or not (due to device and assembly "packaging" specifics).

Long story short, all is figured out except the sealing of the lid against the container, which has to be on the inside of the container as a face-seal is not possible.
This presents a problem as some seals (EPDM, Silicone, NBR etc.) just stick to the glass and the lid cannot be pushed to it's intended position inside the container, while other seals, with low coefficient of friction like PTFE are not pliable enough for this kind of application.

But(!), I think that thanks to , I might have a solution, so thank you sir, for reminding me of this feature of "roughing" up the surface of the glass.


Hopefully this made things clearer, but any additional ideas are more thank welcome.

Thanks,
SD

 

[SnTMan]

"Hopefully this made things clearer"

Well, not really...

Regards

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Compositepro]

I can't believe that there is no off-the-shelf solution for your application. You are not the only one using liquids in a clinical trial. This is exactly what Thermo-Fischer specializes in.

 

[MintJulep]

You might find some material and geometry inspiration here

https://www.fishersci.com/us/en/products/IZ8PFI12/tube-plugs.html

 

[MintJulep]

hermetically seal the glass container and it's contents, meaning that nothing from the ambient environment can interact with the contents.

And

Pressure equalized by a breather valve are mutually exclusive.

But since everything is figured out...

 

[IRstuff]

Yeah, only marginally clearer.

> What exact contamination are you trying to prevent; you've given us YOUR solution, but not what your ACTUAL problem is
> If the lid is removable in use, then the hermeticity is broken, so why does it need to be "hermetic" ?
> Does it matter is someone randomly walks in a opens the lid to look inside? Does that not violate your hermeticity?
> You've shown a commercial solution that does sealing integral to the lid, so no added components, yet you are searching for a different solution, WHY?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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