# 60L fermentor



## calobes (31/7/14)

Hey guys, 

A really quick question: is is ok to use a 60L fermentor for regular 23L sized brews?

I have a 60L fermentor but dont want to do a double batch as ive just started brewing.

thanks!


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## Bribie G (31/7/14)

Works fine, the beer doesn't know how much headspace is above it


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## calobes (31/7/14)

Thanks bribie. I thought it wouldn't be a problem but wanted to be sure. 

Cheers


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## Greg.L (31/7/14)

Bribie G said:


> Works fine, the beer doesn't know how much headspace is above it


The beer might not know but all the aerobic bacteria and film yeast do know, they love all that extra oxygen. Always keep your headspace as small as possible.


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## calobes (31/7/14)

Greg.L said:


> The beer might not know but all the aerobic bacteria and film yeast do know, they love all that extra oxygen. Always keep your headspace as small as possible.


Bugger, thought I was all clear  
Wouldn't gas build up push out any oxygen before co2?


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## Greg.L (31/7/14)

Initially the vigorous fermentation produces lots of co2 which pushes out most of the oxygen. Then you have a steep concentration gradient with almost zero oxygen inside and 20% oxygen outside so the oxygen will move inside. Gases can mix in the same volume, law of partial pressures, so the co2 won't protect your beer from oxygen. If you are 100% sure no bugs can get in your fermenter you will be safe, in the real world you can never be sure no matter how good your sanitising. the safe thing to do is keep a small headspace so your beer is as protected as possible. This is standard practise in most of the world. You can go the "she'll be right" route but eventually you will get an infection.


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## abe max (31/7/14)

I recently got hold of a 60 for free, I threw down a single batch Pacific Ale clone, I just used glad wrap, no air lock.
After a couple of days the wrap had domed nicely, indicating fermentation in full swing, left it for two weeks and bottled.
I put it next to mate's who did the exact same recipe in a standard fermenter, couldn't pick the difference, I'll brew in it again for sure.


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## calobes (31/7/14)

Thanks for the advice guys. I'll play it safe and save it for when I do a double batch.
This forum is going to be alot of help for me lol


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## Greg.L (31/7/14)

abe max said:


> I recently got hold of a 60 for free, I threw down a single batch Pacific Ale clone, I just used glad wrap, no air lock.
> After a couple of days the wrap had domed nicely, indicating fermentation in full swing, left it for two weeks and bottled.
> I put it next to mate's who did the exact same recipe in a standard fermenter, couldn't pick the difference, I'll brew in it again for sure.


I guess if it worked once it must be OK.


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## TheWiggman (31/7/14)

Greg.L, partial pressures and oxygen is a common theme you bring up. You've mentioned the law of partial pressures, but this doesn't explain what you're saying: "The total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases in the mixture"
This doesn't say anything about gasses wanting to move through plastic because there's a higher concentration of a gas in one environment than the other. The difference in pressure will determine that. No difference in pressure (after fermentation), no reason for gas to move. Otherwise nitrogen would get in there first due to its higher concentration in the atmosphere. 
I could be wrong, but I'd love to see a good reference or evidence of it. I can't find any. 
PS: brace up for the snow tomorrow.


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## SnakeDoctor (31/7/14)

calobes said:


> Thanks for the advice guys. I'll play it safe and save it for when I do a double batch.
> This forum is going to be alot of help for me lol


People I know very often do single batches in a 60l fermenter, it's no worries at all.


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## Yob (31/7/14)

I've a shiny new 50l stainless FV for single batch fermenting, 

Greg beats this drum a bit without much supporting evidence, certainly not an issue in the norm.

If it was, the infection photo thread would be quite a bit longer


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## micblair (31/7/14)

Yorkshire squres/rounds are open fermenters - and they don't have any issues with infection.Low pH, hops, alcohol (>3% abv) all safeguard your beer, Besides the beer quickly becomes saturated with CO2, so that rules out all obligate aerobes from harming your beer. She will be right Calobes.


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## calobes (31/7/14)

Thanks alot everyone. Be prepared for more newb question in the close future


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## Greg.L (1/8/14)

TheWiggman said:


> Greg.L, partial pressures and oxygen is a common theme you bring up. You've mentioned the law of partial pressures, but this doesn't explain what you're saying: "The total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases in the mixture"
> This doesn't say anything about gasses wanting to move through plastic because there's a higher concentration of a gas in one environment than the other. The difference in pressure will determine that. No difference in pressure (after fermentation), no reason for gas to move. Otherwise nitrogen would get in there first due to its higher concentration in the atmosphere.
> I could be wrong, but I'd love to see a good reference or evidence of it. I can't find any.
> PS: brace up for the snow tomorrow.


My point is that if a container is full of co2 and not totally sealed, (the situation of a fermenter after the initial fermentation has died down,) the fact that the whole volume is full of co2 doesn't stop oxygen entering. Co2 doesn't have to leave for oxygen to enter, oxygen can get in even as more co2 is being produced. The volume of co2 doesn't affect the oxygen entering. Once it is full no more co2 can get in without increasing the total pressure, but oxygen and Nitrogen can get in without affecting the total pressure, the partial pressures of oxygen and nitrogen will rise but still be less than the partial pressure of co2 so the total pressure will be the pressure of co2.
That is a long winded way of saying that the co2 isn't protecting your beer from oxygen. This science has been known for 200 years.

In terms of brewing it is an established fact that the more oxygen in your headspace, the higher the risk of infection and off flavours. That doesn't mean a big headspace will always cause an infection, it just raises the risk significantly. You can ignore the risk and get away with it for most of the time, especially if your beer is only in the fermenter for 2 weeks. Most gamblers remember the successes more than the failure. Saying " me and my friends do it without problems" is not a scientific approach. If homebrewing is done properly it is a very risk free operation, but I don't think we should be teaching new brewers the most risky methods of fermenting. Personally I don't know why anyone should choose an inferior method when they have gone to a lot of trouble to produce their wort.


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## Yob (1/8/14)

I dont know about you, often my FV's will keep a positive pressure even after active fermentation has ceased, as seen in the bulging gladwrap lid. My Stout thats in now has well and truly finished and still retains the bulge. I think the time frame we use is to our advantage in this respect, I dont believe it warrants the full tilt danger you attribute to it.

I have to disagree that it's "the most risky" The most risky would, to me, be leaving the frementer open under the lemon tree and mowing the lawn beside it.  

Inferior? pffft. Think I'll personally carry on. I dont get many complaints about off flavours in my beers with the methods I employ, inferior methods or not (personal perspective) 

While I do have a SSFV now, Im yet to do a side by side of the same wort in a HDPE FV but rest assured that I will (Both will be done with your arch nemesis... Gladwrap lids.. _grabs hair and runs screaming to the hills_)


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## TheWiggman (1/8/14)

I know Yob. But as you can see OP has conflicting responses and is being led by Greg's advice as much as yours. If he's right, great, and we've all learnt something. But if not then all it's doing is confusing the matter (again).



Greg.L said:


> My point is that if a container is full of co2 and not totally sealed, (the situation of a fermenter after the initial fermentation has died down,) the fact that the whole volume is full of co2 doesn't stop oxygen entering. Co2 doesn't have to leave for oxygen to enter, oxygen can get in even as more co2 is being produced. The volume of co2 doesn't affect the oxygen entering. Once it is full no more co2 can get in without increasing the total pressure, but oxygen and Nitrogen can get in without affecting the total pressure, the partial pressures of oxygen and nitrogen will rise but still be less than the partial pressure of co2 so the total pressure will be the pressure of co2.
> That is a long winded way of saying that the co2 isn't protecting your beer from oxygen. This science has been known for 200 years.


I'd still like to see a good reference or evidence of what you're saying. I'm going to maintain that partial pressures are irrelevent. PROPORTIONS are relevent, who cares about the sum of the pressures of each of the gasses? If there's O2 in there then there's O2 in there. It's not the partial pressures that cause a transfer, it's the absolute pressure.

As far as I'm concerned, the beer won't give two fliers about how much gas is above it, only what's in the gas. I'm as happy to take a breath with 19% O2 in an open field or out of a plastic bag. Same proportion, same effect. 

Let's consider your agument though and assume the head space is 100% CO2 and absolute pressure has reached 1 bar (i.e. in equalibrium with the atmosphere). O2 gets in and forms 2% of the head space and is _maintained _at that proportion.

Is there a difference with 1000l of head space at 2% O2 and 2l of head space at 2% O2? I say no.
CO2 isn't protecting your beer from oxygen? Yes, if there's not a perfect seal.

Head space doesn't matter in the home brewing environment, sealing integrity matters (to a point).


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## abe max (1/8/14)

Greg.L said:


> I guess if it worked once it must be OK.


I was just sharing my limited experience with a 60 and that I would have no problems brewing in it again, I didn't say it's foolproof


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## Greg.L (1/8/14)

Some good quotes from sources.

"Gases will always flow from a region of higher partial pressure to one of lower pressure; the larger this difference, the faster the flow. Gases dissolve, diffuse, and react according to their partial pressures, and not necessarily according to their concentrations in a gas mixture."

"The partial pressure of an ideal gas in a mixture is equal to the pressure it would exert if it occupied the same volume alone at the same temperature. This is because ideal gas molecules are so far apart that they don't interfere with each other at all. Actual real-world gases come very close to this ideal."

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Partial_pressure.html


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## Bribie G (1/8/14)

Guess Black Sheep and Sam Smith have been doing it all wrong.


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## TheWiggman (1/8/14)

Thank you.
This still doesn't give weight to the theory that volume of head space will affect anything. In fact is supports that it doesn't. The partial pressure of O2 in the CO2 enviroment (0) of the headspace won't change based on its volume following a fermentation. It will be zero regardless. In fact you could nearly argue that more head space would be better with this theory. It'll take more time to reach the same proportions as air in the head space, hence less oxidation risk.

Do you have any references brewing-related?


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## Pokey (1/8/14)

Greg.L said:


> Some good quotes from sources.
> 
> "Gases will always flow from a region of higher partial pressure to one of lower pressure; the larger this difference, the faster the flow. Gases dissolve, diffuse, and react according to their partial pressures, and not necessarily according to their [/size]concentrations in a gas mixture."[/size]
> 
> ...


Interesting read but it doesn't seem to mention gas migrating to a higher pressure vessel


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## Greg.L (1/8/14)

for a given pressure of oxygen, if you increase the volume you will increase the mass of oxygen. That oxygen is available to react with the beer and any micro-organisms on the surface of the beer. As the oxygen reacts and dissolves the partial pressure at the surface drops so oxygen moves towards the surface from the headspace, until all the oxygen is consumed. This drop in partial pressure will draw more oxygen into the fermenter. 

Basically the bigger headspace means more oxygen will be drawn in because of the lowering of the partial pressure.

This science doesn't relate just to brewing, it is common for all gas systems. In terms of the desirability of small headspaces, there must be a lot of references but I really can't be arsed. It isn't my problem if people use large headspaces, I just thought I would present the science for your elucidation.


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## Greg.L (1/8/14)

Pokey said:


> Interesting read but it doesn't seem to mention gas migrating to a higher pressure vessel


 The point is that the pressure of oxygen inside is much lower than the pressure of oxygen outside the fermenter.

"Gases will always flow from a region of higher partial pressure to one of lower pressure; the larger this difference, the faster the flow"


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## butisitart (1/8/14)

if you're worried about too much bad air near a good brew, you can always sanitize a couple of 4L capped plastic juice bottles or similar, and throw them in the fermenter. that'll cut down on the air space.


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## TheWiggman (1/8/14)

But that's the point - it's been elucidated but the quoted science doesn't support your view that more head space increases the risk of oxygen spoiling the beer.
Yes the pressure of oxygen inside is lower (I wouldn't say much in absolute terms) than the pressure of oxygen _outside_ the fermenter, but the pressure difference won't change with a larger head space volume. More oygen will be drawn in yes, but that's irrelevent - as the beer might consume it it will just get replaced like you say. REGARDLESS if the volume. I believe it's O2% in the head space of the fermenter that matters, which is what the surface of the beer will see. This won't change with larger head space.

This is a critical point if the basis for your advice is the space in the fermenter head.

I think the only time it matters is where the space is so great that not all the air will get displaced with CO2, or where a measurable percentage of air remains following a ferment. For home brewers not doing open ferments, this won't happen.

My assumptions also support the large quantities of brewers who have successfully done smaller brews in large vessels with success. Might not be raw science, but if you tally up the sample size on this forum of people who have done it then we're talking a serious sample size of brews. If that's not supporting evidence then I'm not here. Soooo many variables in brewing and I've not heard one person quote "I was getting oxidation and/or infection issues which stopped when I used a smaller fermenter".

If there's a specific brewing text that discusses head space and infection risk I'm all ears. Until I see it though I think OP is 99.99% safe doing a small batch in a large fermenter, as are all of us.


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## Greg.L (1/8/14)

TheWiggman said:


> More oygen will be drawn in yes, but that's irrelevent - as the beer might consume it it will just get replaced like you say. REGARDLESS if the volume.


This is the point - that oxygen is not just being consumed by the beer, but by various aerobic microbes (germs). If you think it is irrelevant that more oxygen is being drawn in then I obviously can't convince you. You are obviously more convinced by all the people on this forum who reassure each other that a huge headspace is fine.


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## Yob (1/8/14)

Dismiss as you may the Anecdotal evidence that suggests that it isnt a critical point that will destroy your beer.

Not for the first time, I would also like to see a paper discussing the subject. At a homebrew level.


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## pcmfisher (1/8/14)

This oxygen, is it being drawn in though the plastic fermenter, the airlock, the rubber seal or only when using glad wrap?


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## i-a-n (1/8/14)

I agree with Greg, headspace can be a risk. 
I agree with Yob, gas will flow from a higher ambient pressure to a lower one. 
My take.....use your 60 litre fermenters.... Then.... .. Don't piss about with it, when it's done fermenting get it bottled or kegged. 
You'll be enjoying it sooner that way.


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## TheWiggman (1/8/14)

Greg.L said:


> This is the point - that oxygen is not just being consumed by the beer, but by various aerobic microbes (germs). If you think it is irrelevant that more oxygen is being drawn in then I obviously can't convince you. You are obviously more convinced by all the people on this forum who reassure each other that a huge headspace is fine.


More in the space does not equal more exposed to the beer. I'll make it simple with two scenerios -

100l of headspace, 2% oxygen by weight.
1l of headpace, 2% oxygen by weight.
Oxygen is replaced as it is consumed.

There's more oxygen in the larger headspace, but the environment still has 2% oxygen by weight. If the surface area of the beer is the same in both, why would one absorb any more oxygen than the other?
If there was a sealed lid on it, totally different story. But there isn't, there is an incredibly small ability for gas to transfer.

I'm not sure if you're deliberately misinterpreting what I said or you don't understand. If the proportion of oxygen exposed to the surface of the beer is stable the actual volume of oxygen in the headspace is completely irrelevent.
If I need to breathe, having billions of cubic metres of oxygen in the atmosphere doesn't make the way I breathe any different.
My statement is that oxygen will be consumed at the same rate with both scenerios, for the miniscule amount of oxygen that might make its way in. Nobody on this forum has needed to convince me, looking at the thoery and science in isolation has convinced me. Further reading to the contrary will convince me otherwise, which as I've said I'm still open to.

I seem to be repeating myself. I think I've said enough. Looking forward to a hoppy APA tonight in the snow, where I'll no doubt still be thinking about this trying to work out if the headspace really matters.


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## Greg.L (1/8/14)

pcmfisher said:


> This oxygen, is it being drawn in though the plastic fermenter, the airlock, the rubber seal or only when using glad wrap?


Mainly through the seal and the walls of the plastic fermenter. The volume of headspace is significant partly because at the surface of the beer is where most infections take hold. The yeast cells in the beer act to mop up a fair bit of oxygen. Hop chemicals also have antibiotic powers. The surface of the liquid is where a lot of the action is. If there is a big headspace it is a perfect reservoir of o2 to replenish the needs of bacteria and film yeast. The more headspace, the more oxygen available, though things like acetobacter can work their magic in the liquid as well if there is any dissolved oxygen available. Permeability to oxygen ranges from very high for gladwrap, less for ldpe then hdpe only slowly, glass and S.Steel are pretty much impermeable, but a little bit of oxygen will always infiltrate unless you have a very good seal.


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## AlwayzLoozeCount (1/8/14)

I've been wondering if I can fit a 60 litre fermenter in my ferment fridge for a while now. Can someone please measure the diameter of the bottom of their 60 litre fermenter.... For science.
Thanks in advance.


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## AlwayzLoozeCount (1/8/14)

I've been wondering if I can fit a 60 litre fermenter in my ferment fridge for a while now. Can someone please measure the diameter of the bottom of their 60 litre fermenter.... For science.
Thanks in advance.


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## Crouch (1/8/14)

Yob said:


> I've a shiny new 50l stainless FV for single batch fermenting,
> 
> Greg beats this drum a bit without much supporting evidence, certainly not an issue in the norm.
> 
> If it was, the infection photo thread would be quite a bit longer


i was just reading through that BB thread today ... sad face for me, I missed it.

I've frequently put single batches into a 60l and never had a problem ... now, back to read the rest of the thread.

Thank you


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## pcmfisher (2/8/14)

Greg.L said:


> Greg.L, on 01 Aug 2014 - 4:35 PM, said:
> 
> Mainly through the seal and the walls of the plastic fermenter. The volume of headspace is significant partly because at the surface of the beer is where most infections take hold. The yeast cells in the beer act to mop up a fair bit of oxygen. Hop chemicals also have antibiotic powers. The surface of the liquid is where a lot of the action is. If there is a big headspace it is a perfect reservoir of o2 to replenish the needs of bacteria and film yeast. The more headspace, the more oxygen available, though things like acetobacter can work their magic in the liquid as well if there is any dissolved oxygen available. Permeability to oxygen ranges from very high for gladwrap, less for ldpe then hdpe only slowly, glass and S.Steel are pretty much impermeable, but a little bit of oxygen will always infiltrate unless you have a very good seal.


Can you tell me how much oxygen is going to permeate through my hdpe fermenter in 2 weeks, given that I have a good seal.( My airlock holds an uneven pressure whether it's positive or negative).
I know that a positive co2 pressure does not inhibit o2 but that is not the point.
I am also not concerned whether it is actual volume of o2 or percentage of o2 that is the issue, I want to know how much is going to get through, in say a half full 60L fermenter. 

I propose it is 1/4 of 3/8 of 5/16 of **** all. And whatever does get through makes 0.0% difference. 
If you have to go to more than one decimal place I am not interested.


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## Bribie G (2/8/14)

If oxygen permeates through the walls of plastic containers then the makers of fresh wort kits are a mob of thieving charlatans.


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## Grott (2/8/14)

So does this now mean that everyone that uses the new Coopers style fermenters with the sliding collar insert that you remove during the process have a crook brew for allowing oxygen in during the removal process? In other words Coopers are advising to introduce oxygen to the brew- don't think so.


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## Greg.L (2/8/14)

There is this thing called google, if you search oxygen permeability of hdpe plastic you might get some results. Most fermenters are hdpe.
One site gives a figure for hdpe of 4000 cm3-mil/m2/day but I am not sure what the thickness is. The thicker the wall of the fermenter the less permeable it is but if you use ldpe it is quite permeable. 

As I said the wort itself is more resistant to oxygen but the headspace has a big impact. Oxygen will also get past an o-ring but very slowly, an o-ring is a hell of a lot better than gladwrap and a rubber band.


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## MastersBrewery (2/8/14)

Greg.L said:


> There is this thing called google, if you search oxygen permeability of hdpe plastic you might get some results. Most fermenters are hdpe.
> One site gives a figure for hdpe of 4000 cm3-mil/m2/day but I am not sure what the thickness is. The thicker the wall of the fermenter the less permeable it is but if you use ldpe it is quite permeable.
> 
> As I said the wort itself is more resistant to oxygen but the headspace has a big impact. Oxygen will also get past an o-ring but very slowly, an o-ring is a hell of a lot better than gladwrap and a rubber band.


so basically it's crap beer unless it's fermented in glass or ss. Hmmm interesting, of all those award winners is comps over the years and I'd say more than 90% were using plastic. And if your so sure of the permeability of the glad wrap lid why not test in out and glad wrap yer self in a big plastic container, by your theory you'd be fine!

MB


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## i-a-n (2/8/14)

calobes said:


> Hey guys,
> 
> A really quick question: is is ok to use a 60L fermentor for regular 23L sized brews?
> 
> ...


Really quick question. 

PMSL 

you opened a can of worms amigo.


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## calobes (2/8/14)

i-a-n said:


> Really quick question.
> PMSL
> you opened a can of worms amigo.


lol yeah seems that way. I had no idea I promise!! I opted out, everything became a bit to confusing for a newbie.


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## HBHB (2/8/14)

There's 1 way to find out. Who's got a Photoacoustic spectroscope laying around gathering dust?


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## Batz (2/8/14)

HBHB said:


> There's 1 way to find out. Who's got a Photoacoustic spectroscope laying around gathering dust?


Sounds like something I rather the doctor didn't use on me. :blink:


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## Greg.L (2/8/14)

There's no controversy really, it's just a choice between the "she'll be right" brigade and the " better safe than sorry" camp. The only controversy is when the "she'll be right" brigade try to make out their method is perfectly safe.


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## StalkingWilbur (2/8/14)

Ohh, Greg...


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## i-a-n (3/8/14)

How about filling the fermenter then turning it upside down so the "air" gap is at the bottom?


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## Yob (4/8/14)

Greg.L said:


> The only controversy is when the "she'll be right" brigade try to make out their method is perfectly safe.


all evidence aside that it isnt the end of the world yeah?

Coz you know... every second ferment is oxidized and shit right?


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## GrumpyPaul (4/8/14)

i-a-n said:


> How about filling the fermenter then turning it upside down so the "air" gap is at the bottom?


Is there any scientific evidence to prove that if I did this my gladwrap wont break when I turn the fermenter upside down????


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## Grott (4/8/14)

Now GrumpyPaul, you should know that the molecular contact of the gladwrap with the wort will cause the ionization of ..................


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## mofox1 (4/8/14)

GrumpyPaul said:


> Is there any scientific evidence to prove that if I did this my gladwrap wont break when I turn the fermenter upside down????


It's probably got something to do with partial pressures... h34r: 

In all seriousness to the original poster, try it and see. The worst thing that could happen is that you might need reassurance that it's okay.




Greg.L said:


> You are obviously more convinced by all the people on this forum who reassure each other that a huge headspace is fine.


And we're here for you. :wub:


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## pcmfisher (4/8/14)

Greg.L said:


> Greg.L, on 02 Aug 2014 - 12:52 PM, said:Greg.L, on 02 Aug 2014 - 12:52 PM, said:
> 
> There is this thing called google, if you search oxygen permeability of hdpe plastic you might get some results. Most fermenters are hdpe.
> One site gives a figure for hdpe of 4000 cm3-mil/m2/day but I am not sure what the thickness is. The thicker the wall of the fermenter the less permeable it is but if you use ldpe it is quite permeable.
> ...


OK.
I have seen figures of less than 2000 cm3/mil/m2/day but we will use your 4000.
BTW, /mil is the thickness ie 1 mil = 1/1000 inch. Therefore 1mm = 39 mil.

60 litre fermenter with 20 litres of beer has 40cm of head space at 38cm diameter and I reckon it is about 2mm thick. That's about 0.6m2 of surface area inc the lid above the surface if the liquid.
4000 / 78 x 0.6 = 30cm3 oxygen per day.

A standard 30 litre fermenter has 1/3 of that surface area above the liquid so that makes it 10cm3 per day for that size.



If however you had a 25cm dia bit of glad wrap as a lid.
That is 0.05 m2 but glad wrap is about 0.5 mil thick. (That's mil not mm)

So, 4000 / 0.5 x 0.05 = 400cm3 per day just through the glad wrap.

I don't know if 400cc is a lot of oxygen to pass into a fermenter each day, but I would reckon if people using glad wrap can make beer indistinguishable to those using a lid, I will stand by my original comment.


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## Blind Dog (4/8/14)

pcmfisher said:


> So, 4000 / 0.5 x 0.05 = 400cm3 per day just through the glad wrap.
> 
> I don't know if 400cc is a lot of oxygen to pass into a fermenter each day, but I would reckon if people using glad wrap can make beer indistinguishable to those using a lid, I will stand by my original comment.


It’s a huge amount.

Even assuming that's all the oxygen that gets in there and assuming only 1% gets dissolved into the beer, and assuming that we only have to worry after fermentation is largely complete (so say for 3 days only) that works out as 600ppm of oxygen in 20L (0.4L x 1% x 3 x 1,000,000 / 20L).

The saturation point of oxygen in water is just 14.6ppm at freezing and less than that as it gets warmer.

So I’m not going to drink my beer anymore. I'm going to breathe it. Marvellous


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## Greg.L (4/8/14)

Your calculations seem good but the permeability figures were for hdpe. The figures for gladwrap are a lot higher so probably multiply your figure for gladwrap by ten. I wouldn't be surprised if as you say the figures from that site are on the high side. HDPE fermenters work fine when full because the live yeast can soak up the o2 without problems. It is the o2 in contact with the surface of the beer that causes the problems.


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## seamad (4/8/14)

If your theory on headspace were correct then gladwrappers would have an almost infinte headspace then because of the permability, and would therfore always have oxidised beer ?


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## GalBrew (4/8/14)

Glad wrap is highly permeable to oxygen, far more than HDPE. Whether that will result in noticeably oxidised beer I can not tell you.


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## Greg.L (4/8/14)

My main concern with headspace and gladwrap is the potential for infections, but it can't be good in terms of oxidation either. The basic principle is to always try to minimise the oxygen getting in the fermenter, oxygen contact is one of the variables homebrewers have control over, along with things like temperature, yeast strain, volume, O.G. etc. If you can control a variable then you should be trying to optimise it.


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## Yob (4/8/14)

GalBrew said:


> Whether that will result in noticeably oxidised beer I can not tell you.


I dont seem to get those comments from Comp entries from people trained to detect that sort of thing.. I dont seem to get that from Club members who know of such things.. I dont seem to detect it myself, I know what oxidised beer tastes like...

Seriously.. Every second score sheet would have to have a big oxidised through it if it was a real issue.


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## Greg.L (4/8/14)

In my opinion most infections are caused by oxygen in the headspace. It's a misconception that infections are caused by poor sanitation, infections are usually aerobic organisms and need oxygen. Of course, sanitation is one of those variables, like oxygen exposure, that homebrewers have control over. Obviously it is better to use a clean fermenter than a dirty one, just as it is better to have a small headspace than a big one. It would be foolish to use a dirty fermenter when it is so easy to clean it, and it is foolish to use a fermenter that is too big when it is so easy to get the right size.


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## StalkingWilbur (4/8/14)

Do many people share this opinion?


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## Greg.L (4/8/14)

If you see an infection floating on the surface of your beer, then it is definitely an aerobic infection caused by too much oxygen in the headspace. If it isn't obvious on top but causes a vinegar smell, that is also aerobic. Other infections are harder to diagnose.


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## wereprawn (4/8/14)

Lacto is anaerobic. So are many other problem microbes. Infection and oxidization don't go hand in hand. Plastic fermenters may be permeable/semi-permeable but if the unit is "sealed" then there should not be a problem as bacteria are vastly larger than an oxygen/co2 molecule and should not get into the fv in the amount of time fermentation and conditioning takes place. Positive pressure in the fv would keep nasties out in any case. Bad sanitization/cleaning procedures are the cause.(Or a leaky fv letting the germs in) Just my opinion. Happy to be shown to be wrong.


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## Yob (4/8/14)

Don't you need to have it splashing or surface movement to transfer oxygen to liquid? (in enough to matter)

Pretty sure my fish don't get enough without the pump on...


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## Yob (5/8/14)

Yes, but how much head space?


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## Greg.L (5/8/14)

Infection microbes are ubiquitous in the air. You have to open your fermenter to pitch yeast, that's enough to let infection in. I didn't say all infections were aerobic, just all the ones you see on the surface. (Lacto doesn't sit on the surface). Because they are on the surface they don't need the oxygen to dissolve, but of course oxygen dissolves easily without any splashing or disturbance, splashing just speeds things up. Some strange ideas in this thread, probably just people trying to stir things up.


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## pedleyr (5/8/14)

What is a pity is that you seem to avoid answering the clear and direct questions put to you and instead choose to give vague monologues.


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## Yob (5/8/14)

Anecdotal evidence still says that your fears arent justified. My 23lt of stout in my 50l FV tastes wonderful and still, surprisingly, hasnt turned into a green slimy mess... furthermore, it still has a positive pressure (diminishing I'll grant) a week after terminal gravity has been reached.

You surely arent suggesting that oxygen can force its way into a positive pressurised vessel?


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## Greg.L (5/8/14)

Yob said:


> Anecdotal evidence still says that your fears arent justified. My 23lt of stout in my 50l FV tastes wonderful and still, surprisingly, hasnt turned into a green slimy mess... furthermore, it still has a positive pressure (diminishing I'll grant) a week after terminal gravity has been reached.
> 
> You surely arent suggesting that oxygen can force its way into a positive pressurised vessel?



You obviously haven't read my other posts, the partial pressure of oxygen is lower in the fermenter so it is a negative pressure.


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## Yob (5/8/14)

What is the problem with my post exactly?

I have certainly read your posts... I just don't get how oxygen can 'force' it's way into a vessel full of C02 at a higher pressure than atmospheric.


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## wereprawn (5/8/14)

Greg.L said:


> Infection microbes are ubiquitous in the air. You have to open your fermenter to pitch yeast, that's enough to let infection in. I didn't say all infections were aerobic, just all the ones you see on the surface. (Lacto doesn't sit on the surface). Because they are on the surface they don't need the oxygen to dissolve, but of course oxygen dissolves easily without any splashing or disturbance, splashing just speeds things up. Some strange ideas in this thread, probably just people trying to stir things up. This lacto seems to be on the surface.


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## TheWiggman (5/8/14)

I said I signed out of this but I can't help myself.
That was my argument too Yob but it's not 100% correct. In the atmosphere we have ~21% oxygen at 1 atmopshere (duh) or around 101 kPa. That makes the partial pressure of O2 in the air 101 x 0.21 = 21 kPa for all intents and purposes.
If you have 100% CO2 inside the fermenter, there is 0 kPa of oxygen inside it.

Essentially the law of partial pressures states that each gas will seek a difference of pressure in respect to that gas itself. So the difference in this case is 21 - 0 = 21 kPa. The oxygen will try to get in as though it's applying 21 kPa of pressure on the fermenter.

NOTE that as oxygen transfers (and likewise so will nitrogen, argon and whatever else is around us), the difference drops and the rate of transfer drops too. As more oxygen gets in there, less oxygen tries to get in there.
So you can't say "400 cc/day" or whatever because the difference is not constant. And plus 400 cc/day would make a 20l head space the same as air after 4 days. So that's not even close. The 'cm3-mil/m2/24hr' unit off the website that previous posters are referring to is a nothing unit as far as I'm concerned. cm^3-mil doesn't line up with other units for this same problem in other examples, so I'd be disregarding it completely.

I'm still maintaining it's not a concern for home brewing over short (a couple of weeks) periods.

The ONLY reason I can think that you wouldn't want more headspace is because you will have more air in the fermenter to start with, which could potentially contain more nasties that could spoil the beer. The risk here is, in my opinion, too low to be genuinly concerned about. That judgement is up to each individual brewer. Greg.L certainly won't risk it, I will.

Signing out again...


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## pcmfisher (5/8/14)

Greg.L said:


> Greg.L, on 04 Aug 2014 - 4:01 PM, said:
> 
> Your calculations seem good but the permeability figures were for hdpe. The figures for gladwrap are a lot higher so probably multiply your figure for gladwrap by ten. I wouldn't be surprised if as you say the figures from that site are on the high side. HDPE fermenters work fine when full because the live yeast can soak up the o2 without problems. It is the o2 in contact with the surface of the beer that causes the problems.


Yes, I should have looked up the permeability figures for ldpe which is what glad wrap is made of I think.
As you said, it probably lets is a lot more oxygen.

This only weakens your argument even more.
I just don't understand how it is even possible to make beer without rampant infection letting that much oxygen in using glad wrap.
And seeing as though you can, comparing headspace in a large and small sealed fermenter allowing a small fraction of the oxygen in is trivial.


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## pcmfisher (5/8/14)

TheWiggman said:


> TheWiggman, on 05 Aug 2014 - 09:39 AM, said:
> 
> NOTE that as oxygen transfers (and likewise so will nitrogen, argon and whatever else is around us), the difference drops and the rate of transfer drops too. As more oxygen gets in there, less oxygen tries to get in there.
> So you can't say "400 cc/day" or whatever because the difference is not constant. And plus 400 cc/day would make a 20l head space the same as air after 4 days. So that's not even close. The 'cm3-mil/m2/24hr' unit off the website that previous posters are referring to is a nothing unit as far as I'm concerned. cm^3-mil doesn't line up with other units for this same problem in other examples, so I'd be disregarding it completely.


I think the units are good. volume/thickness/area/time. I don't know what other units you could use.
They are probably some sort of maximum pressure differential permeation that tapers off anyway meaning the actual amount of oxygen is nowhere near the amount stated.

I agree, on a home brewing scale over a short time there is not a problem using glad wrap or a sealed fermenter.


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## pedleyr (5/8/14)

Greg.L said:


> You obviously haven't read my other posts, the partial pressure of oxygen is lower in the fermenter so it is a negative pressure.


What are you talking about? 

The truth of course is that there's nothing wrong with the post. You should withdraw the aspersions you were trying to cast by saying what you have.

Play the issue, not the man, like everyone else here is.


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## Grott (5/8/14)

All I can say from all this science is that all the oxygen effected beers are the ones that taste great and the ones not, are crap!?


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## AndrewQLD (5/8/14)

pedleyr said:


> What are you talking about?
> 
> The truth of course is that there's nothing wrong with the post. You should withdraw the aspersions you were trying to cast by saying what you have.
> 
> Play the issue, not the man, like everyone else here is.


I assume greg.l was referring to a post that has been removed for offensive language, however since it wasn't removed within 30 seconds of it being posted he chose to question our ability to do our job.
Greg, sometimes we don't see a post and it takes a report to be lodged to bring it to our attention, when that happens the post is acted upon as soon as we see it.


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## mje1980 (5/8/14)

Gregs gunna have kittens when he sees how I did my last porter, and intend on doing my next IPA.


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## AndrewQLD (5/8/14)

mje1980 said:


> Gregs gunna have kittens when he sees how I did my last porter, and intend on doing my next IPA.


 Nice Yorkshire square there mje1980.


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## mje1980 (5/8/14)

Thanks mate, I was hoping for that horribly infected character a lot of great English ales have. Sam smiths etc. Worked so well I'm keen to do a few more in it.


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## drsmurto (5/8/14)

As a scientist who is paid to research the impact of oxygen in wine (amongst the many hats I wear) there are a few points that need clearing up.

During active fermentation, gladwrap, or no lid is fine, not perfect but in a homebrew situation, ok. Once fermentation slows down the gas laws that have been bandied around will come back to haunt you. There is nothing to stop oxygen getting back in to your fermenter as there is no measureable positive pressure. I've fermented many times with gladwrap, it domes during active fermentation and then collapses well before fermentation is complete. As others have pointed out, plastic is not an oxygen barrier. The sooner beer is transferred to keg/bottle, the lower the risk of oxidation.

Ask any winemaker/brewer who does this for a living whether they would leave wine/beer exposed to air post-fermentation. Any amount of headspace will contain oxygen due to the partial pressures discussed previously. Yes, even in wine which has a lower pH, higher ethanol content and vast amounts more naturally occurring anti-oxidants plus the ubiquitous addition of sulphite in large quantities, is very susceptible to oxidation once fermentation is complete. Winemakers go to great lengths topping up wine in storage and actively removing oxygen from the headspace, the best way to do so is to reduce the amount of headspace itself so wine is stored in vessels as close to capacity as physically possible. Stainless steel vessels with rubber seals. Beer is a sitting duck by comparison.

I recently stored wine in a 1000L HPDE plastic 'cube'. In 6 weeks, despite removing the oxygen in the headspace using dry ice (CO2) daily, sitting in a 0C room, the sulphite content dropped dramatically (41mg/L free SO2 to 25mg/L). Why? Oxygen was getting in to a sealed plastic container and reacting with the sulphite. Imagine a similar situation with a beer, cold conditioning in a cube/jerry can. No sulphite to protect it.

In working in this area I control oxygen levels down to parts per trillion and to do so requires a lot of effort and positive pressures in ss vessels. As I mentioned, there is no positive pressure in a fermenter or at least not anyway near high enough to prevent oxygen from getting in to your fermenters.

Despite flushing my anaerobic chambers in the lab down to <1ppt oxygen using nitrogen, and storing under a positive pressure of nitrogen all the time, I still measure an increase in oxygen concentration within days. They are flushed back down to <1ppt weekly. We measure the daily increase in oxygen in sealed glass wine bottles under a variety of closures and they all allow oxygen in. Yes, even screwcaps.

Using beer judging results to justify this is laughable. As someone who is also BJCP Certified the 'training' is non existent. Taste a few beers, answer a few questions and you get qualified. Let's not even go in to how many orders of magnitude easier it is now. I'd wager large amounts of money that the vast majority of beer judges, myself included, would fail a simple blind judging test we put wine sensory panellists though. Beer judging is a subjective and all results should be taken accordingly. 

Using the open fermenters as evidence? Please. How long do they allow beer to sit in those fermenters? A few days of fermentation and they will be protected from oxygen by transferring to sealed vessels.

Hats off to GregL for attempting to help fellow AHBers out, I don't know why he bothers giving the response.

And with that, I'll disappear back in to the ether.


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## superstock (5/8/14)

So for the home brewer, PET vessels, solid PET O ring bungs and dry one way airlocks are the recipe for the least o2 in the brew. Regardless of headspace.


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## Vini2ton (5/8/14)

Who was that masked man? Must of escaped from a laboratory. Destroying our entertainment, by sense and science. The nerve.


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## mje1980 (5/8/14)

No you're exactly right. At the end of fermentation, absolutely I don't want oxygen near my beer, but at the start, I like lots. My "square" beer gets siphoned after a few days, for that reason. That's what most uk breweries who use squares. But a blanket statement that oxygen is bad for beer is wrong.


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## Lord Raja Goomba I (5/8/14)

Good response, Doc.


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## Yob (5/8/14)

A goodly amount of info , while I take on board what's been put forward, I think it's a managed risk and what seems to have come to the top is that though there is a 'risk' it still seems negligible in a hb environment, certainly from a perception point of view. 

Thanks to greg and doc for the info and entertainment.. 

I'm still not going to worry too much though and if I start to get infections I'll be sure to eat my words here


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## Vini2ton (5/8/14)

I'm going to put my fermenter under my lemon tree and mow the lawn tomorrow....lid off.


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## TheWiggman (6/8/14)

Signing in again...

I'd like to say that I value to input of Greg.L and it's clear you're no dope. The discussion here is valuable and I certainly was in the wrong with my original assumptions regarding pressures. Partial pressure is a dificult concept for me to grasp but the systems I deal with almost exclusively deal with flow conditions. Where flow doesn't exist, the principles change.
I completely accept and have accepted (after being corrected) that oxygen will get in. The matter remains though of headspace [volume] affecting a brew. Greg.L's comments are that oxygen is the enemy with regards to infections, and I'll take his word for it (though I can't find much about it online. Sanitation, yes, which is probably why so many members here are more concerned about that because by and large that's the message you get when sitting behind a keyboard.)

I'll disregard the area of a fermenter which is making contact with the wort. The rate of transfer will be constant regardless for a small brew.

The larger the surface area, the greater the rate of transfer of oxygen (as the permiability coefficient is [quantity x thickness] / [area x time x Δp] )
Doing some maths on paper the relationship between fermenter area : headspace is -

Surface area : headspace
d + 4·l : d·l

Where l is the height of the headspace and d is the diameter of the drum/fermenter.

For a case where the headspace is very, very low, the surface area is much greater than the voume
For a case where the headspace is infinitely high, surface area will be 4 x the volume.
So the greater the headspace, the lower the surface area in respect to the volume. In layman's terms, it will take _longer_ for oxygen to acheive the sample proportion by volume with a larger headspace due to ingress via permiability. This favours larger headspace.

What DrSmurto is talking about is managing the oxygen proportion within a headspace. The smaller the headspace, the easier this would be to manage. In addition if the vessel (cask, conical SS fermenter etc.) has any sort of taper at the top then by topping it up you are reducing the surface area of the liquid to the gas about it, which is favourable. This isn't typical of your standard home brew bucket or Coopers fermenter.

I completely understand that minimising headspace is ideal to manage the proportion of oxygen within that headspace.
As homebrewers with simple fermenters and no real means for managing the oxygen content, I'm still confident larger headspace won't increase the proportion of oxygen inside the fermenter's headspace. Quantity yes, proportion no.

All that aside the most important message I've got from all this discussion is to be careful about leaving fermented beer in an HDPE container for extended periods. This is a habit I have for lagers and is something I'll look at changing. Especially considering Greg.L's comments about the increased risk of infection with oxidation.

Attached is the maths for above for those interested. Not signing out. 

View attachment 3791_001.pdf


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## Feldon (6/8/14)

Trying to replicate the stringent measures employed by commercial brewers to eliminate oxygen from their beers is all well and good. But does it really matter on the home brew scale?

My understanding is that chemical reactions that lead to stale oxidised beer occur faster if the beer is subject to high temps, agitation and light.

Commercial brewers have a much tougher job in making sure their beers reach their consumers without going stale. Its a rough world our there for commercial kegs and pallets of slabs due to the trauma of industrial transport and storage.

But for the home brewer, whose beers rarely travel more than several metres from where they are made, the rate of chemical reaction must be much reduced. And therefore stay fresher for longer. I think this is evidenced in practice by home brewers, most of whom I would think make their beers to be consumed fairly soon, whereas commercial brewers are aiming for as long a shelf life as they can manage.

So keep your home brew beers cool, dark and still.

And for bottlers, wouldn't the residual yeast used in bottle fermentation scavenge most or all of the oxygen dissolved in the beer?


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## i-a-n (6/8/14)

Speaking of science, I've a science degree so here's my take on it. Just do what we used to do as students studying science. Ferment in fermentation vessel for a week, tap straight out of the vessel into a pint glass mix with cheap cider. Repeat about 8times a night, Bingo! 
Worked for us.


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## hotmelt (6/8/14)

You could always minimise the head space by inflating a food grade balloon with co2.


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## Bribie G (8/8/14)

Here's an idea.
There must be a gas that cannot permeate HDPE plastic. So if you fill a sealed HDPE vessel with that gas, then according to previous posts the Oxygen in the atmosphere will migrate into the vessel through the walls until the oxygen outside the vessel is in equilibrium with the oxygen inside the vessel.

Thus if your original gas in the vessel was at one atmosphere, by the time the oxygen has entered the vessel the pressure would be far higher as the original gas is unable to escape. Say two atmospheres.

So if you take a series of a large number of vessels and using spunding valves or sealed pistons or something you could use this difference in pressure to turn wheels, generate electricity etc.

When the vessels have been returned to one atmosphere, the oxygen can be removed, either by a reducing agent or getting kittens to breathe it or whatever and start again.

The Bribie Oxygen engine has been invented.


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## TheWiggman (8/8/14)

Aha! But the actual pressure will not change! Just the composition (as the oxygen gets in, other said gas will go out).
Will need to find another use for your kittens.

Ed: why has nobody commented on the spelling of the thread title?


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## mje1980 (8/8/14)

No ones noticed, they're too outraged at the thought of oxygen


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## Feldon (8/8/14)

I think the thread title is strictly correct.

A fermentor is a vessel in which fermentation occurs, just as a reactor is a vessel in which a reaction (eg. nuclear) occurs.

A fermenter is something that causes fermentation (eg. yeast is a fermenter).

Six of one etc... whatever pops your airlock.


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## TheWiggman (8/8/14)

Well I'll be buggered.


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## i-a-n (8/8/14)

TheWiggman said:


> Well I'll be buggered.


Is that strictly within the remit of this forum?


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## Yob (8/8/14)

Hay wadda-ya-know, my stout didn't turn fungal.. Left for a week (or so) after terminal gravity, 

As a refresher, single batch, 50l (ss) FV


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## Blind Dog (8/8/14)

[SIZE=medium]Oxygen is bad for fermented beverages. HDPE lets in oxygen, and lots of it. Bungs and airlocks also let in loads even if they fit snugly. And size does matter (maybe)[/SIZE]

[SIZE=medium]Last week I hadn’t given it much thought at all. Now I’m worried and looking to change my fermenters. I’ve not really had an issue with oxidisation yet, but I never want one either. [/SIZE]

[SIZE=medium]For that alone, it’s been an interesting read. So thanks to all[/SIZE]


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## Yob (8/8/14)

If it ain't a problem you can detect, it ain't really an issue, 

the beer I make doesn't last long enough to stale


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## Blind Dog (8/8/14)

Yob said:


> If it ain't a problem you can detect, it ain't really an issue,
> the beer I make doesn't last long enough to stale


Don't talk sense when I'm trying to justify to myself the cost of upgrading to SS fermenters. It's just not fair


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