Interesting - silicone o-rings on kegs allow o2

[sibelman]

nice shade of purple : )

It would be handy if color reliably matched material, but that's not the reality. Dang. For all I know, the white o-rings I replaced (to up my anti-oxygen game) were not silicone at all. Fortunately, the cost of "known good" replacements is quite modest.

 

[mac_1103]

Really? Why does everyone here say Buna-N? Is that someone's trademark?

It was BASF's trade name through 1988. I guess maybe we should call it NBR instead.

 

[mashdar]

Think it's safe to assume torpedo factory gasket is not silicone? (Black, couldn't find a spec.)

Re the yellow material, morebeer says "Rather than the usual EPDM or Silicone, Low2 gaskets are made from a unique composition of Synthetic M-Class and Cross-Link Elastomers."

 

[tracer bullet]

Funny, I think EPDM is M-Class and a cross linked elastomer.

 

[mac_1103]

But it's a unique composition!

 

[tracer bullet]

To be fair, whatever they've come up with, aside from the marketing, is probably actually better. But I'd be willing to bet it's a very minor improvement.

 

[mac_1103]

According to the data, it's a >25-fold improvement over silicone. But there's no data on how it compares to the other alternatives.

 

[mashdar]

This seems to imply nitrile is ~1/20 (edit to 1/3) the O2 permeability of EPDM.
https://www.applerubber.com/hot-topics-for-engineers/the-permeability-of-rubber-compounds/
edit: I'm sure it matters how it compresses, though.

 

[tracer bullet]

This seems to imply nitrile is ~1/20 (edit to 1/3) the O2 permeability of EPDM.
https://www.applerubber.com/hot-topics-for-engineers/the-permeability-of-rubber-compounds/
edit: I'm sure it matters how it compresses, though.

I do believe you are correct (also, NBR is nitrile / Buna if anyone wonders). I wonder if SL is silicone? I won't assume it, just wonder.

Related is: O-Ring Permeation Chart | Marco Rubber & Plastics | Custom O-Rings Supplier

It does not show O2 unfortunately, but with the remaining gasses one can see a clear trend and make their own assumptions.

 

[mac_1103]

This seems to imply nitrile is ~1/20 (edit to 1/3) the O2 permeability of EPDM.

Maybe I'm reading the table wrong, but it looks like the O2 permeability ranges overlap.

edit - oops, I was reading the wrong column

 

[Spivey24]

Hmm, the guy in the video seems pretty sure that CO2 under pressure has little to no effect on the O2 permeability, and he seems to know what he is talking about in general. That being said, I would have liked the test to have been done under similar conditions to a pressurized keg, because it just seems counter intuitive.

I do have one keg lid with an off white ring that I will probably replace now.

Also wondering about the keg lids on my fermenters that have silicone rings.

 

[Bassman2003]

This falls under the category of "just do it". The science on the cold side is your friend and oxygen gets in. Buy the EVA Barrier tubing and change all of the keg seals to Buna-N. It will make a difference, especially if you tend to have beers on tap for longer than a few weeks. It really is not very expensive for the benefit.

Gas flow is complicated to understand. I am still working on it but just think of them all being independent of outside forces like pressure. They penetrate surfaces and can be moved, but only en masse. Think of trying to broom mud out of water. If you apply force, only that small bit affected by the force will be moved.

 

[mac_1103]

the guy in the video seems pretty sure that CO2 under pressure has little to no effect on the O2 permeability

This is pretty well established. The diffusion any one gas across a membrane depends on the partial pressure gradient of that gas across the membrane and is independent of the partial pressure gradients of other gasses.

 

[beersk]

This is pretty well established. The diffusion any one gas across a membrane depends on the partial pressure gradient of that gas across the membrane and is independent of the partial pressure gradients of other gasses.

Can you taste it in your beer? Can you tell when the beer is changing or just getting more refined in flavor? Is your beer sitting in the keg long enough for this to be a factor (if so, why?)?

I doubt it. This is not worth stressing over. I'm so glad that this is a hobby where we can see the BS we want to do and ignore the BS we don't want to do and still find joy in the hobby. Because when I see threads like this, I think, good god, what now? As one of the early adopters of low o2 brewing, THIS is a waste of time and effort.

 

[mac_1103]

I was only responding to the question of whether the diffusion of one gas is affected by the pressure of another gas. It is well established that it is not. Rates? I really have no idea how long it would take to get enough O2 through any particular type of o-ring for it to impact the beer inside. What you want to stress over is up to you.

 

[KegLand]

Acknowledging this is a guess, I'd guess silicones won't be black. A vendor would have to add a healthy amount of additional material to do it, and ad cost to the product. For no real reason other than aesthetics, and o-rings aren't really sold on that. Also would guess at least some Amazon vendors mislabel their products intentionally or accidentally to get more hits during searches.

I am not sure which ones you are talking about but we have seen many black silicone o-rings from China and we see these in Australia all the time.

Silicon can be manufactured in many different colors and the carbon black colorant is basically the cheapest tint you can use so it's frequently added.

Black tint for silicone costs about $80 per kg but one kg is enough to tint about 1.5ton of material. So the cost to tint the o-ring is literally a few cents.

Unfortunately it's not uncommon for sellers to not even know what their o-rings are made from. One of the reasons we made this video is we wanted customers to put pressure on their retailers so people start to actually care about this issue which has not had enough attention previously.

I really love silicone for many other applications but for long term storage vessels of beer in particular I think it's a terrible option.

Another common issue is that we have started to see a lot of swing top bottles also with silicone. In many respects this is even worse than the kegs as the surface are to volume ratio is really quite poor on these. Historically swing top bottles were made with Buna-N/Nitrile but now almost exclusively we see the use of silicone in swing top bottles. I think customers inadvertently have been wanting silicone as it doesn't perish like the old buna-n/nitrile seals and most retailers went out and sourced swing top bottles with silicone seals. I think we have to blame ourselves for this poor education so we need to raise awareness of this issue too.

 

[Unicorn_Platypus]

Switching gears slightly to the topic of rubber seals for swing top bottles.

It is ridiculous to me that most vendors use silicone. I tried searching for alternatives and I believe the seals morebeer uses are better than silicone. I raised a ticket with morebeer and this was the best information they had on the material. See text in green below

Does anyone know how "TPE" performs in terms of permeability vs. other rubbers? I can tell you that these seals do feel like they would less permeable (much thicker rubbery feeling than silcone)

There is a homebrewer in my club who only bottles and doesn't keg. His beers were all terribly oxidized until I hooked him up with these seals as replacements. Dramatic improvement! He even one a recent club competition with these. Leads me to believe these ones are the good ones.

Link to morebeer seals:

https://www.morebeer.com/products/rubber-washer-swing-tops.html
Morebeer response:
" I wanted to let you know that I was able to get some information about these gaskets. It looks like the type of rubber used is TPE elastomer rubber, vulcanized rubber. Here is some further information our supplier provided:


Thermoplastic elastomers resist pressure excellently. This means you can apply pressure to it and it will flex to resist. However, when you release the pressure, the TPE quickly regains its original shape.

Thermoplastic elastomers also have chemical resistance against various materials, including alcohols, dilute alkalis, resistance to oil, fats, hydrocarbons (aliphatic and aromatic), etc. TPE performs well even in adverse weather conditions.

Unfortunately, they don't have any information on permeability.

I hope this helps! Please don't hesitate to reach out if you have any other questions or concerns. "

 

[tracer bullet]

TPE elastomer rubber

Might be Buna then. Silicone and EPDM are thermosets.

TP is ThermoPlastic, meaning it can melt, take a shape, and then melt again to take a new shape. Thermosets would burn instead of melting.

 

[Unicorn_Platypus]

Might be Buna then. Silicone and EPDM are thermosets.

TP is ThermoPlastic, meaning it can melt, take a shape, and then melt again to take a new shape. Thermosets would burn instead of melting.

Seems like Buna-N is a TPE material, you're right!

https://patents.google.com/patent/CN102453267A/en

 

[mac_1103]

Then why does it say "silicone" in the description on MoreBeer's website? I have about 150 swing tops. It drives me crazy that most of the available replacement washers are made of silicone, but it drives me even crazier when I can't tell what they're made of.

 

[Unicorn_Platypus]

Then why does it say "silicone" in the description on MoreBeer's website? I have about 150 swing tops. It drives me crazy that most of the available replacement washers are made of silicone, but it drives me even crazier when I can't tell what they're made of.

I may have posted a bad link. Here's the correct one. Don't think this one says silcone. I edited my last post with this link

https://www.morebeer.com/products/rubber-washer-swing-tops.html

 

[mac_1103]

OK, that's a little better. I think I've got a small pack of those lying around somewhere. Guess I should add 100 to my next MoreBeer order.

 

[sibelman]

I wonder what the gaskets in ordinary bottle caps are made of. But I don't wonder very much.

 

[Unicorn_Platypus]

Kegland just dropped these Low2 seals on the market for swing tops. Coming soon to US

Who knows if they are better than the morebeer ones I posted about above, but good to know these ones have been tested for permeability. If the price is comparable I may switch to these when I run out.

I can confirm though that the morebeer ones have been working great! I had a black IPA bottles for 6 weeks off the keg and absolutely no oxidation

https://www.kegland.com.au/products...myrYhQwgJ2rCIx7TyR0dLV1A1CFIZFFJMmlaryrAB1aH0

 

[mashdar]

Kegland just dropped these Low2 seals on the market for swing tops. Coming soon to US

If they're anywhere near that AUS price point, I'll be getting a few packs ASAP to try out.

 

[Unicorn_Platypus]

If they're anywhere near that AUS price point, I'll be getting a few packs ASAP to try out.

Fwiw the ones I've been using from morebeer that I posted about above have been great

Recently had a black ipa bottled for 6 weeks and zero oxidation

 

[tracer bullet]

I can confirm though that the morebeer ones have been working great!

Cool. Thickness has a lot do do with permeability as well, any permeable material is worst when thin and better the thicker it gets. Seals on flip-tops give any O2 a pretty decent path to travel to reach the beer. Might take a long time for enough O2 to get through to make a difference you can taste.