No oxygen dry hopping

[mongoose33]

Thanks for your reply but I see a couple of holes:

1) Opening the keg and adding the hops defeats the purpose of purging in a way. Maybe a quick lid opening is not that bad but in theory O2 gets in.

No, actually not. You're then using the CO2 from the fermenter to purge whatever might have gotten in there with the hops.

2) Why would you need to suspend the hops when a transfer to the keg will be for spunding or just force carb? Either way the fermentation is largely finished at this point.

Well, it was to keep them from creating nucleation points for bubbles to form. Maybe that wouldn't be a big deal if you just let the bag sit on the bottom of the keg.

3) I ferment in a wine fridge so there is no way to run anything from the fermenter. I could just open the lid, drop the hop bag and purge again with tank CO2 but I am not convinced the oxygen would be pushed out given the way gasses mix.

If you purged enough times it would be. But maybe that's no desirable. That's why I went to using fermentation gases.

Since I am spunding, maybe the residual fermentation would eat up most of the oxygen from the lid opening and we can just call it a day? It is a conundrum with the use of corny kegs that were not designed for this use. Maybe a little O2 just has to lived with for dry hopping at the homebrew level?

If you're racking with a few points remaining, that would be a reasonable way to try to scrub oxygen that gets in with the hops.


As far as your fermenting in a wine fridge and can't get the gases out, let me suggest two ideas that might allow that.

One is to drill a hole in a spot not used by the cooling coils and run tubing out of that. Here's how I did that in my small ferm chamber:



The second way, maybe more elegant, is to use a bulkhead shank to pass the CO2 from inside to the outside. I did this on my large ferm chamber to both connect CO2 so I could force carb kegs inside it, as well as pass CO2 out of the fridge to either monitor fermentation, or to run it through a keg to purge it.



The shanks use MFL fittings so you can connect tubing, CO2, whatever. I also use those on my keezer so I can keep the secondary regulators outside but feed the gas to the inside:



You can get them from the Chi Company:

http://www.chicompany.net/index.php...46_425&zenid=b3da20325e896ef6f4ff3d86b06d3da7

 

[Vale71]

Since I am spunding, maybe the residual fermentation would eat up most of the oxygen from the lid opening and we can just call it a day?

Unfortunately that's never the case. For one thing, it takes a lot of time for the oxygen to move from the headspace into the beer, so by the time fermentation is finished there'll still be plenty of oxygen left to do some damage during maturation. And then we have the fact that yeast strongly favors anaerobic metabolism so most of the oxygen that does make it into the beer in time will still be left there leaving plenty of potential for oxydation.

 

[Bassman2003]

Thanks for your replies. Mongoose, great setup and appreciate your photos. Still seems like a tough issue though.

How about an idea from left field? Since we are trying to stop O2 from getting in certain areas which are pretty small, what about creating an O2 free bag or chamber to do the dirty work in? Sort of like an O2 free bubble.

Make a clear bag with gloves in, put it over the keg top, purge it, open the keg and drop the hops in. Would be simple if the bag could be made and purged easily. A chamber would be larger & harder to purge but would offer more room for transfers or fermentations.

All of the O2 fear is coming from the environment so change the environment. Just an observational thought.

 

[Bassman2003]

Nobody likes or dislikes my bag idea? I have thought about it a little more and might have a simpler approach. One might not need any gloves. If a plastic bag could have a ball lock gas in attached, one could lay your hop bag on the keg top, squoosh the bag down, tape it around the side of the keg to seal, inflate/flush with CO2 and then open and drop the hops in. Close it back up and done. Hope fully the bag would be flexible enough to allow you to open the keg and drop the hop bag in. No gloves needed.

Getting the gas in post involved and attached might be a challenge. But the concept of creating a temporary O2 free zone has legs imho. Thoughts?

 

[G Scott Stukey]

OK, time to report! Finally had a chance to try out the butterfly valve/sight glass/pressure manifold thing to introduce dry hopping hops, and I'm pleased to report that....it worked!

Here's a short video showing how it went down:

@mongoose33 - did this technique improve the quality/taste of your DH’d beer? I just picked up a Spike Flex+ and am considering getting a sightglass & extra butterfly valve just to do this.

 

[mongoose33]

@mongoose33 - did this technique improve the quality/taste of your DH’d beer? I just picked up a Spike Flex+ and am considering getting a sightglass & extra butterfly valve just to do this.

It was great just after I kegged it. Note that today's post is July 3rd, and that video was posted April 25. So that beer has been on tap for 2+ months. I just had a couple glasses last night, and it's still excellent. The name of the oxygen game here is to eliminate the staling of the hop aroma/flavor, and this beer still smells great and tastes as well. I've often thought a good indicator that a beer tastes good to me is whether, when the first glass is emptied, is my first thought to refill the glass again?

Last night, this was the first thought: "That was good, I'd like some more."

I figure if you can hold an IPA for 2+ months and it's still great, then that's a validation of the approach. YMMV, maybe it would taste better or worse to you, who knows? All I know is that this is now my standard practice for dry hopping an IPA.

 

[Jag75]

It was great just after I kegged it. Note that today's post is July 3rd, and that video was posted April 25. So that beer has been on tap for 2+ months. I just had a couple glasses last night, and it's still excellent. The name of the oxygen game here is to eliminate the staling of the hop aroma/flavor, and this beer still smells great and tastes as well. I've often thought a good indicator that a beer tastes good to me is whether, when the first glass is emptied, is my first thought to refill the glass again?

Last night, this was the first thought: "That was good, I'd like some more."

I figure if you can hold an IPA for 2+ months and it's still great, then that's a validation of the approach. YMMV, maybe it would taste better or worse to you, who knows? All I know is that this is now my standard practice for dry hopping an IPA.

I just want to know how you managed to make it last this long lol.....oh wait are you doing 10 gallon batch ? My 5 gallon IPA lasted bout 3 weeks

 

[mongoose33]

I just want to know how you managed to make it last this long lol.....oh wait are you doing 10 gallon batch ? My 5 gallon IPA lasted bout 3 weeks

I have six beers on tap right now....a dark lager, light lager, amber, hazy IPA, rye ale, and a kolsch. Hard to make a choice there.....

 

[Jag75]

I have six beers on tap right now....a dark lager, light lager, amber, hazy IPA, rye ale, and a kolsch. Hard to make a choice there.....

Dang that's quite a bit of beer Mr. Lol

 

[Mer-man]

It was great just after I kegged it. Note that today's post is July 3rd, and that video was posted April 25. So that beer has been on tap for 2+ months. I just had a couple glasses last night, and it's still excellent. The name of the oxygen game here is to eliminate the staling of the hop aroma/flavor, and this beer still smells great and tastes as well. I've often thought a good indicator that a beer tastes good to me is whether, when the first glass is emptied, is my first thought to refill the glass again?

Last night, this was the first thought: "That was good, I'd like some more."

I figure if you can hold an IPA for 2+ months and it's still great, then that's a validation of the approach. YMMV, maybe it would taste better or worse to you, who knows? All I know is that this is now my standard practice for dry hopping an IPA.

I think what you did was cool, but I will add that spunding onto hops has done the same for me. I am trying to finish off an IPA I kegged April 18th (it's a little strong ABV-wise) and the hop character is great.

 

[Dog House Brew]

It was great just after I kegged it. Note that today's post is July 3rd, and that video was posted April 25. So that beer has been on tap for 2+ months. I just had a couple glasses last night, and it's still excellent. The name of the oxygen game here is to eliminate the staling of the hop aroma/flavor, and this beer still smells great and tastes as well. I've often thought a good indicator that a beer tastes good to me is whether, when the first glass is emptied, is my first thought to refill the glass again?

Last night, this was the first thought: "That was good, I'd like some more."

I figure if you can hold an IPA for 2+ months and it's still great, then that's a validation of the approach. YMMV, maybe it would taste better or worse to you, who knows? All I know is that this is now my standard practice for dry hopping an IPA.

That is an awesome setup for adding dryhops. I really need to add a conical or two.

 

[mongoose33]

I think what you did was cool, but I will add that spunding onto hops has done the same for me. I am trying to finish off an IPA I kegged April 18th (it's a little strong ABV-wise) and the hop character is great.

That's actually what I'm doing, albeit in reverse order. I close up the fermenter with about 7-9 points of gravity to go (for a 5-gallon batch; 5 points is enough for a 10-gallon batch). Then it self-carbonates--spunds, if you will--but I want to dry hop toward the end. This lets me get the hops in there devoid of oxygen, at least as much as I can. I'm sure a little gets in, but by not waiting until it's completely done, I get the benefit of the yeast cleaning up any oxygen that does get in there with the hops.

 

[balrog]

I thought yeasts use of O2 was in the propagation stage and not the fermenting stage?

 

[brewbama]

1. Lag Phase: After pitching Beer Yeast to your wort, you will experience a lag period which varies from strain to strain, and from beer to beer; 12-24 hours is normal. The lag phase will also be impacted by the degree of oxygenation of your wort and by temperature. During the lag phase the yeast is acclimatising to its new surroundings, multiplying by budding, taking up free oxygen and nutrients from the wort, and its metabolism is shifting out of dormancy to active state.

2. Fermentation: For the first 48 hrs, don’t be concerned by the little or absence of activity in your airlock or in the beer. Most strains will show vigorous activity within 12 hours, but lagers in particular such as Bavarian Lager and Bohemian Lager yeasts will nearly always require over 24 hours to produce any krausen or bubbling in your airlock

3. Maturation: Generally, beer reaches premium flavor potential after approximately 4 weeks maturation: 1-2 weeks in fermenter, followed by 2-3 weeks in bottles or other storage vessel. However, there are exceptions to this rule.

 

[Vale71]

I thought yeasts use of O2 was in the propagation stage and not the fermenting stage?

Yeast is facultative anaerobic, meaning it can process sugars aerobically as well and will do so any time it has access to oxygen.

 

[Vale71]

1. Lag Phase: After pitching Beer Yeast to your wort, you will experience a lag period which varies from strain to strain, and from beer to beer; 12-24 hours is normal. The lag phase will also be impacted by the degree of oxygenation of your wort and by temperature. During the lag phase the yeast is acclimatising to its new surroundings, multiplying by budding, taking up free oxygen and nutrients from the wort, and its metabolism is shifting out of dormancy to active state.

What you described there is actually a composite of the lag phase and the log phase. During the lag phase the yeast is acclimatizing to its surroundings and adjusting them as well (PH drop!). How long this lasts is dependent on the yeast's vitality and on the wort (higher OG = longer lag phase). In the log phase reproduction finally kicks in and cell count starts increasing exponentially, which is why the latter should actually be named the exponential phase but somebody like the term log phase better and we're now stuck with it.

 

[hopjuice_71]

Yeast is facultative anaerobic, meaning it can process sugars aerobically as well and will do so any time it has access to oxygen.

Well, sort of. When O2 is present and sugar concentrations are low yeast will aerobically respire, as opposed to ferment. However, with high sugar concentrations aerobic respiration is suppressed by the Crabtree effect. O2 is used up for other metabolic processes (e.g. biosynthesis) but the sugar is fermented to ethanol (i.e. O2 is not the final electron acceptor from the oxidation of the sugar carbons). We rely on this effect when we pitch yeast into aerated wort.

 

[couchsending]

I personally don’t think you need to be super anal about O2 pickup when adding dry hops of you have a conical.

I will put the pressure transfer TC piece on my Chronicals at the tail end of primary fermentation, it’s attached to a manifold that’s hooked up to Co2.

I’ll let fermentation finish, leave for 2 days and then soft crash to 55/60 for a day before pulling yeast. The PRV accommodates for maybe 2-3 pSi of head pressure, enough to maintain head pressure during the soft crash. When I add dry hops I’ll turn the Co2 on, pull the pressure transfer piece, and using a funnel dump the hops in as fast as possible, then reattach the pressure transfer piece that’s already pushing Co2. Once it’s installed I’ll pull the PRV a few times to purge the headspace, then leave as much head pressure as I can while dry hopping. Been rousing with Co2 through the transfer port every now and again lately.

I get zero aroma or flavor drop off over the course of 2-3 months. I have 7-8 beers on tap at a time so inevitably one will last that long.

In an ideal world I’d like to push Co2 into the headspace while I’m adding the hops. Just got a Spike CF5 which will allow me to do that although I wish there was a second 1.5” TC port on those lids instead of having to dump through the huge port on top.

 

[SanPancho]

Lotsa folks make 4” lids with tcs and other fittings. Jay at norcal can give you pretty much anything you want if it fits.

Sorry for the long link. Cant copy the image file.

https://www.ebay.com/itm/FNPT-Tri-C...rentrq:bdb06fe516b0abc665b19e14ff8f952d|iid:1

 

[Mer-man]

That's actually what I'm doing, albeit in reverse order. I close up the fermenter with about 7-9 points of gravity to go (for a 5-gallon batch; 5 points is enough for a 10-gallon batch). Then it self-carbonates--spunds, if you will--but I want to dry hop toward the end. This lets me get the hops in there devoid of oxygen, at least as much as I can. I'm sure a little gets in, but by not waiting until it's completely done, I get the benefit of the yeast cleaning up any oxygen that does get in there with the hops.

Ok, I like that even more! I appreciate that you've worked out the headspace v. spunding relationship.

As luck would have it, I kicked that 3 month old IPA last night, and it hard distinct, bright hop character to the last drop.

 

[ihavenonickname]

I’m doing the magnet suspended hop bag method I saw @RCope do.


My method:
Day 3 active fermentation dropped 3 oz of hops and stirred them in. Then using tape and magnets I suspend 3 more oz of hops to the lid of the fermenter, the open end of the bag is held up by a magnet in the inside and outside. (https://imgur.com/gallery/xqkxUoA)

Then day 6 I’ll soft crash to 58F to drop the yeast, I use a co2 capture device like the cold crash guardian.

Day 7 I’ll pull the exterior magnet to dump the hops into the wort. Lid stays closed and no o2 exposure.

Then day 10 closed transfer to a purged keg.



The potential issue I see is once I release the hops I will have to swirl the fermenter around to get all the hops in contact with wort. Hope that works. Also the swirling is probably going to reshape d some yeast I was trying to avoid.

Open to any feedback or ideas as to how to do this better.

 

[balrog]

At this point I feel like Satchel in Get Fuzzy.
Does the yeast scavenge the O2 when adding dry hops or not?
Also, some of us don't have conicals.

I may have to stick to brewing altbiers and give a hard pass on the 8 month desired shelf life citrussy hop forward things.

 

[Iseneye]

In the log phase reproduction finally kicks in and cell count starts increasing exponentially, which is why the latter should actually be named the exponential phase but somebody like the term log phase better and we're now stuck with it.

Is it because growth is logarithmic, rather than exponential? Exponential growth means it grows forever while logarithmic means it grows rapidly then slows down.

 

[mongoose33]

At this point I feel like Satchel in Get Fuzzy.
Does the yeast scavenge the O2 when adding dry hops or not?
Also, some of us don't have conicals.

I may have to stick to brewing altbiers and give a hard pass on the 8 month desired shelf life citrussy hop forward things.

Yes.

But the game is still to limit O2 as much as possible. The O2 isn't just waiting around for the yeast to consume it; it's also looking for things to oxidize, so as little as possible is the order of the day.

 

[Gravitysucks]

I personally don’t think you need to be super anal about O2 pickup when adding dry hops of you have a conical.

I will put the pressure transfer TC piece on my Chronicals at the tail end of primary fermentation, it’s attached to a manifold that’s hooked up to Co2.

I’ll let fermentation finish, leave for 2 days and then soft crash to 55/60 for a day before pulling yeast. The PRV accommodates for maybe 2-3 pSi of head pressure, enough to maintain head pressure during the soft crash. When I add dry hops I’ll turn the Co2 on, pull the pressure transfer piece, and using a funnel dump the hops in as fast as possible, then reattach the pressure transfer piece that’s already pushing Co2. Once it’s installed I’ll pull the PRV a few times to purge the headspace, then leave as much head pressure as I can while dry hopping. Been rousing with Co2 through the transfer port every now and again lately.

I get zero aroma or flavor drop off over the course of 2-3 months. I have 7-8 beers on tap at a time so inevitably one will last that long.

In an ideal world I’d like to push Co2 into the headspace while I’m adding the hops. Just got a Spike CF5 which will allow me to do that although I wish there was a second 1.5” TC port on those lids instead of having to dump through the huge port on top.

I don't know if you got a cooling coil with your CF5 but if you did there's enough room on the 4" TC cap to weld on a 1.5 TC ferrule which you can attach your manifold to and frees up the lid 1.5 TC for adding hops or other things.

I did this to my CF10 so I could add a scaled down version of a hop canon I put together. Originally the idea was that I could use the co2 pressure that builds up in the fermenter to purge the O2 out of the hops through the purge valve on the hopper then use my CO2 tank attached to the second manifold to push the hops into the fermenter. I've also realized that if I remove the second manifold, cap that fitting off, and install a TC screen gasket above the butterfly valve I may be able to fill the hop canon up then recirculate wort through it using the purge valve which might allow dry hopping with less hop debris (possibly with leaf hops).

I realize it all probably overkill especially since I've had the CF10 for 6 months now and still haven't manage to get a batch into it but it was a fun project.

 

[G Scott Stukey]

It was great just after I kegged it. Note that today's post is July 3rd, and that video was posted April 25. So that beer has been on tap for 2+ months. I just had a couple glasses last night, and it's still excellent. The name of the oxygen game here is to eliminate the staling of the hop aroma/flavor, and this beer still smells great and tastes as well. I've often thought a good indicator that a beer tastes good to me is whether, when the first glass is emptied, is my first thought to refill the glass again?

Last night, this was the first thought: "That was good, I'd like some more."

I figure if you can hold an IPA for 2+ months and it's still great, then that's a validation of the approach. YMMV, maybe it would taste better or worse to you, who knows? All I know is that this is now my standard practice for dry hopping an IPA.

Could you share what your process is for what you have on your fermenter and what process & when you change things?

 

[eric19312]

OK, time to report! Finally had a chance to try out the butterfly valve/sight glass/pressure manifold thing to introduce dry hopping hops, and I'm pleased to report that....it worked!

Here's a short video showing how it went down:

Cool video. Would a larger butterfly valve handle the dry hops without the thumping? I’m thinking I’ll not use the coil so have that 4” TC opening available with quite a few options up to a true 4” butterfly and a 4” sight glass.

Do you purge the site glass after adding the hops? How does that work? Is tank pressurized doting this process?

 

[mongoose33]

Could you share what your process is for what you have on your fermenter and what process & when you change things?

Here's a link to a post I made earlier in the thread--might be worth slogging through the whole thread just to see the evolution of this approach--that shows closeups of the equipment I'm using:

https://www.homebrewtalk.com/forum/threads/no-oxygen-dry-hopping.663500/page-3#post-8552371

Here's the idea: how to get the hops to drop in the fermenter without bringing oxygen along with them.

I attach the butterfly valve to the TC port on top of the lid at the outset and attach the pressure manifold to the butterfly valve. I use the gas post on the pressure manifold to bleed off the CO2 produced during fermentation, and I terminate the tubing in an airlock jar.

The reason for using the pressure manifold is that it has the PRV on it, which you need to ensure you don't build up too much pressure later in the fermentation.

So--I have the butterfly valve installed, the pressure manifold attached to that, and the butterfly valve cracked open just a bit to let the fermentation gases escape out the pressure manifold. At this point, pretty standard.

I also have a TILT hydrometer inside the fermenter so I can monitor gravity during fermentation. I also can monitor it through the bubbling in the airlock jar. When I have about 10 points of gravity remaining in fermentation--this seems to correspond somewhat to a slowing of the bubbling in the jar, i.e., krausen falls--I will close the cracked-open butterfly valve to seal the unit for a moment. I'll remove the pressure manifold, drop in my dry hops, then reattach the pressure manifold.

At that point, I crack open the butterfly valve just enough to let pressure escape, up through the sight glass, taking the oxygen in the sight glass and which came in with the hops, out through the tubing terminating in the airlock jar. In other words, at this point I'm using the CO2 produced by fermentation to purge the oxygen around the hop pellets, creating an oxygen-free environment in the sight glass.

When I get down to about 5-7 points of gravity remaining, I open the butterfly valve and let the hops drop in. That's what you see in the video. I then remove the gas QD from the pressure manifold, letting the pressure build as the remaining fermentation proceeds. The PRV on the pressure manifold then ensures I don't exceed the pressure rating of the conical. In my case, it releases at 13 psi.

Why am I closing up the fermenter? I want to self-carbonate the beer as much as I can, similarly to what happens with bottle conditioning. I get, after crashing, beer carbonated to about 7psi, which is about 1.5 volumes of CO2. I then can quickly burst-carb it in the keg after transferring, or do set-and-forget, which doesn't take as long as the beer is already carbed to 7psi.

You could also do this without the pressure--just let the fermentation finish before dropping the hops, then seal it up.

****

I hope that was clear, I fear it wasn't completely so. Consult the pics, and the video, and hopefully it will be clearer.

 

[mongoose33]

Cool video. Would a larger butterfly valve handle the dry hops without the thumping? I’m thinking I’ll not use the coil so have that 4” TC opening available with quite a few options up to a true 4” butterfly and a 4” sight glass.

You nailed it. If you could do it through the larger opening w/ a 2" sight glass instead of the 1.5" sight glass I'm using, not only would the hops tend to bridge less and fall right through, you'd have more capacity for hops. If my p*r-squared calculations are correct, you'd get about 70 percent more capacity for hops.

Do you purge the site glass after adding the hops? How does that work? Is tank pressurized doting this process?[/QUOTE]

The sight glass is already purged by the escape of fermentation gases (CO2) produced by fermentation. I crack open the butterfly valve enough to allow gas to escape, but not enough to drop the hops, so those gases purge the sight glass.

The conical is no more pressurized at this point than if you had a simple blowoff tube submerged in a jar of star-san.

 

[kevink]

The only thing I would do different is the purging of the site glass after the hops are in it. Why would you not blow CO2 in through the top and crack the tri-clamp fitting above the valve to purge it? Seems like you would get a much more complete purge this way since you have an unlimited amount/pressure of CO2 from your tank than compared to the little bit of pressure in the fermenter. Sure, some hop dust will get on the sealing surface, but they are squishy enough to not be a problem (I usually get a little hop dust on my tri-clamp sealing surfaces during dry hopping and they seal just fine).

Another way you could to it is to do it your way but blow CO2 into the fermenter that would then pass by the butterfly valve and up through the sight glass.

Another way you could do it is to add a gas in port between the valve and the sight glass and push gas up through the hops and out the top.

Anyway, nice setup. Curious to hear your thoughts.

 

[SEndorf]

This thread started with kicking around a few concepts using simple magnets and baskets, then progressed to a solid solution.
I continue to be impressed with you engineer types. Not my skill set.
Great contributions by all and I'd say the Mongoose nailed it.

 

[mongoose33]

The only thing I would do different is the purging of the site glass after the hops are in it. Why would you not blow CO2 in through the top and crack the tri-clamp fitting above the valve to purge it? Seems like you would get a much more complete purge this way since you have an unlimited amount/pressure of CO2 from your tank than compared to the little bit of pressure in the fermenter. Sure, some hop dust will get on the sealing surface, but they are squishy enough to not be a problem (I usually get a little hop dust on my tri-clamp sealing surfaces during dry hopping and they seal just fine).

If I did it that way, I'd be purging the O2 from the hops and blowing the O2 into the fermenter which I do not want to do.

Another way you could to it is to do it your way but blow CO2 into the fermenter that would then pass by the butterfly valve and up through the sight glass.

Yes, you could do that, but it's really not necessary to have a separate ingress for CO2.

Another way you could do it is to add a gas in port between the valve and the sight glass and push gas up through the hops and out the top.

At this point we're adding extra parts but they won't add much as the issue can be solved either by gas from the fermentation, pressure from the fermentation, or simply by pressurizing the fermenter and using that pressure to bathe the hops in CO2.

Anyway, nice setup. Curious to hear your thoughts.

Thank you. It came out of a collaboration in this thread of a lot of people, i.e., what about this, what about that, and eventually an answer emerged.

********

Here's something I think people are missing, something I learned via low-oxygen brewing techniques, specifically spunding. That's when you transfer the fermenting beer to a keg with about 5 points of gravity remaining; that 5 points of fermentation will produce about 2.5 volumes of CO2. Or, about 1 volume per every 2 points of gravity.

In other words, carbonating the beer naturally, similarly to how it's done conditioning in the bottle.

One volume is 5 gallons of CO2! So if I'm letting fermentation gases go through the hops, it's actually quite a bit of CO2. It's why I like using that to purge kegs (which I sometimes do), or to flush O2 from hops.

I don't know if you want to go down the rabbit hole of spunding, but that knowledge is partly what led to my using the sight glass. Fermentation produces a TON of CO2, and we can use that. And, IMO, should.

Here's a short video showing the rate of CO2 production from my fermenter: imagine that gas going through the sight glass and purging the hops:

 

[mongoose33]

This thread started with kicking around a few concepts using simple magnets and baskets, then progressed to a solid solution.
I continue to be impressed with you engineer types. Not my skill set.
Great contributions by all and I'd say the Mongoose nailed it.

I guess you could call me a carpenter, then, but remember that others in this thread held the nail and handed me the hammer.

 

[kevink]

If I did it that way, I'd be purging the O2 from the hops and blowing the O2 into the fermenter which I do not want to do.

That is not what I mean. I proposed to leave the valve closed and crack the tri-clamp fitting above the valve. It will give the hops a great purge and nothing will get in the fermenter.

 

[mongoose33]

That is not what I mean. I proposed to leave the valve closed and crack the tri-clamp fitting above the valve. It will give the hops a great purge and nothing will get in the fermenter.

I'm sure you'd get a lot of the air out of the sight glass, but not all of it. It's better than nothing, but to completely clear it, you'd want to pressurized, purge, pressurize, purge, repeatedly like doing it with a keg.

 

[kevink]

Maybe I'm misunderstanding what you're doing, then. Do you feel you are not getting all of the air out of the sight glass with your method?

 

[mongoose33]

Maybe I'm misunderstanding what you're doing, then. Do you feel you are not getting all of the air out of the sight glass with your method?

Yeah, maybe I'm not explaining this well.

And no, I'm not concerned about not getting all the air out of my sight glass. I'm virtually certain that I am. replacing the air with CO2 from fermentation.

*****

One thing I learned along the way--can't remember where, except it was on HBT--was that it takes about 25 full-pressure purges of a keg to purge it of air. Well, I'm not a fan of that, because I hate buying CO2.

That's why I like purging a keg by pushing a keg full of Star-San into another keg (or 5-gallon bucket). It only takes one volume of CO2 to do that...well, somewhat more than 1 volume, but certainly nothing close to 25 5-gallon purges.

Here's where, IMO, it gets interesting. If you recall the above post that it takes about 2 gravity points of fermentation to produce 1 volume of CO2, then if you vent the CO2 produced by a 1.060 wort into the Liquid OUT post of a keg, crack the PRV, and your beer finishes at 1.010....you'll have almost perfectly purged that keg. No star-san. No anything.

Starting at 1.060, ending at 1.010....that's 50 points of gravity. Two points of gravity will produce a volume of CO2. So 50 points-worth of CO2 produces about 25 volumes of CO2. And that's enough to purge a keg. Cool!

But I'm not purging a keg. I'm purging a sight glass whose volume is about a half cup. So even a single 5-gallon volume of CO2 is enough to purge that. There are 32 half-cup volumes in 5 gallons, so that's enough.

 

[leesmith]

Yeah, maybe I'm not explaining this well.

And no, I'm not concerned about not getting all the air out of my sight glass. I'm virtually certain that I am. replacing the air with CO2 from fermentation.

*****

One thing I learned along the way--can't remember where, except it was on HBT--was that it takes about 25 full-pressure purges of a keg to purge it of air. Well, I'm not a fan of that, because I hate buying CO2.

That's why I like purging a keg by pushing a keg full of Star-San into another keg (or 5-gallon bucket). It only takes one volume of CO2 to do that...well, somewhat more than 1 volume, but certainly nothing close to 25 5-gallon purges.

Here's where, IMO, it gets interesting. If you recall the above post that it takes about 2 gravity points of fermentation to produce 1 volume of CO2, then if you vent the CO2 produced by a 1.060 wort into the Liquid OUT post of a keg, crack the PRV, and your beer finishes at 1.010....you'll have almost perfectly purged that keg. No star-san. No anything.

Starting at 1.060, ending at 1.010....that's 50 points of gravity. Two points of gravity will produce a volume of CO2. So 50 points-worth of CO2 produces about 25 volumes of CO2. And that's enough to purge a keg. Cool!

But I'm not purging a keg. I'm purging a sight glass whose volume is about a half cup. So even a single 5-gallon volume of CO2 is enough to purge that. There are 32 half-cup volumes in 5 gallons, so that's enough.

So how much bottled co2 would it take to purge that half cup volume?

 

[mongoose33]

So how much bottled co2 would it take to purge that half cup volume?

Not a tremendous amount, about a volume's worth. But to do that, you'd have to have the equipment to pressurize/purge, and then do it, what, 25x? I don't have such equipment, unless one considers tightening and releasing a TC clamp 25x a job to which one can look forward.

There's another issue I haven't mentioned, primarily because I know it may cause a couple heads to explode. That is, bottled CO2 isn't pure, unless you've taken pains to purchase that. Beverage CO2 probably is 99.5% pure. The rest? Air and such. Air is 21% oxygen, so even with bottled CO2, you're not getting a perfect purge.

Perfect? Not in purging a keg (pushing Star-San, say), and not in purging hops. How much does it matter? You decide. As for me, I'm always moving toward perfection, if I can. It's simply a personal philosophy--do the best I can. Using fermentation CO2 is pure, and I'd rather use that than bottled CO2, if I can.

It's why a lot of LODO brewers do spunding of their beer, which is to move the fermenting beer, with about 5 points of gravity remaining, into a keg to finish. Seal up the keg, and voila! Carbonated beer without using bottled CO2 which isn't perfectly pure.

I'm doing a variation of that, sealing my fermenter and carbonating it partially in the same way. Problem is, I have to complete the carbonation using bottled CO2, which is impure. But there's less O2 going into my beer that way than if I'd just carbonated using bottled CO2, about 2/3 less.

I've seen the results of this care in the length of time my beer stays good while on tap. Months. So I keep plugging away, trying to eliminate O2 as much as possible. Seems to work.

There are many in this thread trying to puzzle this out. Whether it's worth it depends on one's motivation, sensitivity to oxidation, time to empty before oxidation has serious consequences to flavor, resources, time, and so on. If it cost me $5000 to get the last bit of O2 out, I wouldn't do it. But if it costs me $50 to try, well, I will.

 

[kevink]

Not a tremendous amount, about a volume's worth. But to do that, you'd have to have the equipment to pressurize/purge, and then do it, what, 25x? I don't have such equipment, unless one considers tightening and releasing a TC clamp 25x a job to which one can look forward.

You don't have to do that. You simply crack the tri-clamp once and flow gas through the hops for 15, 30, 60 seconds or whatever. It will be a more complete purge than a little puff of CO2 up through the hops from the fermenter. Just trying to help dial in your process. If you're content now and not looking to optimize it, then that is fine. Keep doing what you're doing.