Looking for a clear tri-clover cap, so I can see in my stainless fermenter. I have found both Polycarbonate and Acrylic. Which one is less Oxygen permeable? Is the difference enough to matter? Any other reasons to pick one over the other? Thanks!
Polycarbonate vs Acrylic - Oxygen Permeability Question
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I'd be more worried about which one is food grade... I believe poly would be your best choice.
fwiw, Google informs me that polycarbonate is more O2 permeable than acrylic by an order of magnitude...
Cheers!
Cheers!
More details, I plan on putting holes in the cap for gas and liquid posts as well as a PRV. The stainless cap I have has those already and working great, but I want to see inside. Seems as though polycarbonate will be easier to drill, acrylic says it can chip. Is the higher level of Oxygen permeability an issue? Is it up to the level of silicone? Is the level for Acrylic to high? I do closed transfers, fermentation purge kegs, etc. to limit O2 and won't do this if it is going to be a step backwards.
Of course, if one is holding pressure in the fermenting vessel via a bubbling airlock, I wonder how much oxygen can permeate inwards?
Gas laws say O2 molecules don't care about your presumed CO2 pressure and will pass through regardless...
Cheers!
Cheers!
We have gone to a lot of effort to make these already from PPSU that has favorable oxygen transmission rate:
https://kegland.com.au/products/2-inch-tri-clover-sight-glass-lens-ppsu
In addition to that the PPSU has better chemical resistance and does not leach BPA or other endocrine disruptors into your beverage like polycarbonate.
I should also say that acrylic has one considerable issue that it has quite poor resistance to high percentage ethanol. So if you have this come in contact with the sight glass it can cause the acrylic to get small cracks in the surface.
The only downside is that PPSU is not completely clear. It has a slight brown tint to it which is the natural color of this resin.
https://kegland.com.au/products/2-inch-tri-clover-sight-glass-lens-ppsu
In addition to that the PPSU has better chemical resistance and does not leach BPA or other endocrine disruptors into your beverage like polycarbonate.
I should also say that acrylic has one considerable issue that it has quite poor resistance to high percentage ethanol. So if you have this come in contact with the sight glass it can cause the acrylic to get small cracks in the surface.
The only downside is that PPSU is not completely clear. It has a slight brown tint to it which is the natural color of this resin.
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Power to you if it works, but one stubborn disconnect is likely to crack a plastic cap (maybe even one that isn't stubborn). Both acrylic and polycarbonate are a lot more brittle than the PET lids on fermonsters and those face cracking issues if you're not careful.
https://www.homebrewtalk.com/thread...lete-closed-transfer-system-for-cheap.680992/
Is it really that important to see inside?
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Apologies for the extra post... Right after I typed the above I thought it through a bit more and have an alternative to offer;
Just install another TC port:
https://www.brewhardware.com/product_p/tc2wlf.htm
..and add the disconnect/PRV combo;
https://www.brewhardware.com/product_p/sankeball.htm
Just install another TC port:
https://www.brewhardware.com/product_p/tc2wlf.htm
..and add the disconnect/PRV combo;
https://www.brewhardware.com/product_p/sankeball.htm
Does the lens color prevent skunking?
Not really. Visible light and violet light in particular can still pass through the lens. If you want to eliminate all chance of skunking then you really can't have a lens that you can see through. You really can't have both.
I guess you could wrap some aluminum foil over the lens which would prevent this when you are not using it. That might be your best option.
I haven't used my Spike fermenters in a while, but when I first got them and was brewing more, I wound up replacing the clear 4" triclover cap with the stainless blank. The two biggest issues why were, the clear caps didn't seem to hold pressure as well as the stainless ones. The second, the clear cap would bubble up with condensation to where I couldn't see inside which was the whole point of them being clear to begin with.
Thanks for all the replies. I wasn't worried about skunking since the fermentor is in a chest freezer, I assume that would prevent it. I can't add a second TC, should have mentioned this is a SS Brewtech Bucket with the domed lid, no room. Well, maybe it could be welded on but not interested in that cost. I will move past this fermentor to something nicer in the future, save the money for that. I am concerned about cracking, during drilling and beyond, so that does seem like a potential show stopper. @Yesfan has what seems like the final straw in the idea, condensation. I didn't consider that. Just yesterday I transferred out and was cleaning. The inside of the lid was covered with condensation. I've been flying blind for years, what's a few more.
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Off topic, but do your PP duotight rigid stems have any kind of O2 barrier?
I am sorry but this has not been tested. I know our duotight fittings in general have very good O2 barrier but the PP rigid tube has not been tested.
I never claimed to be a lawyer...
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