Pressurized Closed Loop Corny Keg Fermenting

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I ferment in corny kegs - always do split batches of 7gal - 3.5gal into each keg.
Day 0 - fermenting keg, water purged and wort added.
Day 0 - serving keg, water purged then dryhop added (keg hops) - hold for now
12-24hrs - gas "in" from fermenting keg to "out" of serving keg with dryhops. "In" of serving keg to sanitzer so that ferment gas flows thru bith an escapes. This CO2 purging continued until about 60-72hrs post pitch.
60-72hrs - biotrans dryhop added to fermenting keg. Gas out removed from serving keg to allow pressure to build in both fermenting & serving kegs. Spund to 22lbs. Separate & seal serving keg.
Day 10 cold crash fermenting keg for two days.
Day 12 transfer to serving keg for the final dryhop (serving keg still pressurized) beer naturally carbed from spund.
Day 14 chill, gas and serve
 
When I refer to adding dry hops to a water purged keg I think of what is described above ie. Water purge keg, depressurize, add dry hops, re pressurize. As opposed to simply "purging" in the initial step without water.
 
crane said:
What's the point of water purging if you open the lid and let oxygen in with your dry hops? There is no possible way to add hops without adding oxygen.
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If you can feed in CO2 at a low pressure (say around 3psi) to a fully water-purged keg while quickly opening the lid, adding dry hops, and resealing, I’d be willing to wager that the O2 concentration in the keg at the end of the process is better than you’d get by 20 cycles of a purge-release type purging, while using less CO2 in the process.
 
By water purging first you get 99% CO2 in serving vessel. Removing the lid to add dryhop WILL introduce atmospheric O2 BUT it will mix with the CO2 at a rate slow enough that the O2 concentration in keg is still lower than in atmosphere - therefore minimizing oxidation of dryhops waiting in keg (pelletized hops are not so fragile that will ruin from oxidation in a matter of hours). Approx 12 hrs later a steady stream of 100% pure CO2 will be introduced to said keg. This offgassing from fermentation will provide enough CO2 to mix in serving keg to drive up the concentration back to 99%+ (offgassing is enough to purge five kegs).


As a side note - I have tried the single large dryhop at biotransformation (6 batches), spund and serve in same fermentation keg to try to get the true benefit of closed loop / no O2 induction. I did not like the result. Flavor was definitely there but the aroma was substantially lacking versus a double dryhop (assume yeast stripped it out). I incorporated the double dryhop I outlined previously (crash before final dryhop - see Monkish brewing podcast) with closed loop fermentation and the results are outstanding. When pouring from tap aroma can be smelled 6foot away. Flavor is amazing too. Longest keg I have had is two months before empty - no appreciable differences in flavor/aroma at the end.

I use 8lbs/bbl hops. 5% hops in boil, 25% hops whirlpool, 35% biotrans hop, 35% dryhop #2
 
cheesebach said:
If you can feed in CO2 at a low pressure (say around 3psi) to a fully water-purged keg while quickly opening the lid, adding dry hops, and resealing, I’d be willing to wager that the O2 concentration in the keg at the end of the process is better than you’d get by 20 cycles of a purge-release type purging, while using less CO2 in the process.
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This is kind of what I do but with an extra step if I have to open the keg:

-Hook a purged CO2 keg or or if you're not overly anal about commercial CO2, the cylinder up to the gas post on the keg you wish to dry hop into.
-Quickly add dry hops and put the lid in but leaving it a tiny bit cracked open slightly off alignment.
-If you're using a CO2 keg you have to have a valve inline on your jumper hose to meter the flow rate!! Connect CO2 keg or cylinder and turn gas on at a reasonably low flow rate and allow it bleed in through the gas port, into the head space and out through the cracked lid.
-After 10 seconds or so, with the gas still flowing, move the lid into position and it should seal up instantly.

I believe with this method there is sufficient agitation of the head space with the CO2 flowing that there should be little to no O2 in the keg after you seal it up. I agree with you in thinking that purging via displacement is far superior rather than the pressurize and release method. And I agree with you, this is better than pressure purges in many ways.

Baldilocks_Brewing said:
I use 8lbs/bbl hops. 5% hops in boil, 25% hops whirlpool, 35% biotrans hop, 35% dryhop #2
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I liked the looks of these ratios. I might have to give this a go.
 
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Well sh*t, turns out I have a yeast allergy...:( (Gas, bloating, loose stool, etc)

In spite of that I still plan on brewing my faves - Hazy IPAs & Pilsners. I have been reading all of the relative posts on here from folks that have similar issues. It looks like the best option is a plate filter. Question for all you oxidation gurus - any suggestions to minimize O2 exposure in the closed loop corny transfer with a plate filter?
 
Baldilocks_Brewing said:
Well sh*t, turns out I have a yeast allergy...:( (Gas, bloating, loose stool, etc)

In spite of that I still plan on brewing my faves - Hazy IPAs & Pilsners. I have been reading all of the relative posts on here from folks that have similar issues. It looks like the best option is a plate filter. Question for all you oxidation gurus - any suggestions to minimize O2 exposure in the closed loop corny transfer with a plate filter?
Click to expand...


Do you think you could try cold crashing and using gelatin finings as a first step? I think that is advisable before using a plate filter anyway if you need to go that route to prevent clogging the filter prematurely.
 
stickyfinger said:
Do you think you could try cold crashing and using gelatin finings as a first step? I think that is advisable before using a plate filter anyway if you need to go that route to prevent clogging the filter prematurely.
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I do cold crash before transfer. I haven't tried fining though. I will give that a shot on the next batch.
 
Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?
 
A normal 1.050 or so fermentation can purge a couple of kegs based on the math I've seen so I would guess about half you high krausen time would be sufficient.
 
leesmith said:
Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?
Click to expand...
I've found the water purge too time consuming and arduous. What I do now is sanitize the serving keg, purge the sanitizer through the picnic tap, then let the CO2 run for a bit through the keg and out the picnic tap. Between that and fermentation, I'd be surprised if there's any O2 left in it by the time it's done.
 
leesmith said:
Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?
Click to expand...

I guess what I'm getting at is if it takes an hour of full on high krausen co2 production to clear out an already co2 tank purged SV keg to zero o2 then I'd might try to put some hops in the SV, purge by co2 tank, and then FV purge the last remaining bit of o2 with a spunding valve to hold some pressure. Then disconnect the pressurized SV and keep it chilled during the remainder of the FV primary; to keep the hops fresh. Then reconnect at the end of fermentation to close transfer onto the 2nd dry hopping that's in the SV. Priming the FV before transfer.

IF it takes a long time (hours or days) to clear the SV of all o2 then I wouldn't want to leave the hops in the SV for fear of heat destroying the aroma and flavor of the hops.
 
I’ve dropped water purging in favor of fermentation gas purging. Much easier.

I use all the fermentation gas once fermentation has started. I wait until it starts so I’m not pushing the oxygen rich head space of the freshly oxygenated fermenter through the kegs.

It does require you use all the fermentation gas though. Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.
 
schematix said:
I’ve dropped water purging in favor of fermentation gas purging. Much easier.

I use all the fermentation gas once fermentation has started. I wait until it starts so I’m not pushing the oxygen rich head space of the freshly oxygenated fermenter through the kegs.

It does require you use all the fermentation gas though. Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.
Click to expand...

But do you think it’s possible that an already co2 tank purged keg could give up the ghost (100% o2 purge) in a short period of time if connected to a FV?
 
schematix said:
Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.
Click to expand...
Do you remember the post? I'd like to see those numbers. The pressure up and release is very ineffective but that's not the method I'm talking about here, which is hooking the gas up and having it flow out an open picnic tap via the beverage post dip tube at atmospheric pressure. In a perfect world, all you'd need is one keg volume of CO2 displaced through but obviously there is no way to ensure that all the CO2 you're putting in is 100% displacing O2, there is a lot of mixing happening.
 
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How do you calculate how much sugar to add to a pressure fermented beer. My beer finished at 16psi after adding dry hops and is at 1.010 and ready to prime before transferring. Do I do the full amount of sugar or half? OR some other measurement?
 
leesmith said:
How do you calculate how much sugar to add to a pressure fermented beer. My beer finished at 16psi after adding dry hops and is at 1.010 and ready to prime before transferring. Do I do the full amount of sugar or half? OR some other measurement?
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Went for it with the full amount of priming solution. Figure I’ll just spund to relieve excessive pressure.

Used hannabrew’s injection method...screwed it up a little but I’ll get it on the next go around. Worked great.

IMG_2699.JPG
 
enormous13 said:
Wow, that's ingenious...Could you do hop extract in the same way? To get around opening the keg for dry hopping...
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I have yet to use hop extract but I would worry about it being too sticky to pass through everything.

the syringe method may work better for hops extract as there is less to go through, you can make sure it's all pushed through, and it's easier to clean if it is sticky
 
Andre3000 said:
Do you remember the post? I'd like to see those numbers. The pressure up and release is very ineffective but that's not the method I'm talking about here, which is hooking the gas up and having it flow out an open picnic tap via the beverage post dip tube at atmospheric pressure. In a perfect world, all you'd need is one keg volume of CO2 displaced through but obviously there is no way to ensure that all the CO2 you're putting in is 100% displacing O2, there is a lot of mixing happening.
Click to expand...

This isn't the original post on the topic, but has the same data.

https://www.homebrewtalk.com/forum/index.php?posts/8351644
 
crane said:
This isn't the original post on the topic, but has the same data.

https://www.homebrewtalk.com/forum/index.php?posts/8351644
Click to expand...

See, that is a "pressure and release" purge and I believe those numbers are sound for that method. But like I said what I do is different: hook the CO2 cylinder up to the gas post and a picnic tap up to the bevage post. Once I drain the remaining starsan, I allow the CO2 to run through the keg for a bit.
 
stickyfinger said:
For example:

https://www.morebeer.com/products/distilled-hop-oil-chinook-1-ml.html

Do they have oils that are from dried hops though? I think most of them are from wet hops aren't they? That would be very different in character.
Click to expand...

I just got some of that stuff a couple weeks ago and am planning to use it soon. Going to make my IPA the same as always, except halve the dry hops (down to about 6oz from 12oz) and split the 1mL between 2 kegs. Will probably add it to some vodka first so i can get a more accurate dosing.

I've never made a 'wet hop' beer before so i'm not really sure what to expect.

AFAIK there are hop oils made from steam distillation of pellet hops, as well as supercritical CO2 extraction. I believe the CO2 stuff is what you normally see as like a HopShot and is used for bittering. It must be boiled.
 
schematix said:
I just got some of that stuff a couple weeks ago and am planning to use it soon. Going to make my IPA the same as always, except halve the dry hops (down to about 6oz from 12oz) and split the 1mL between 2 kegs. Will probably add it to some vodka first so i can get a more accurate dosing.

I've never made a 'wet hop' beer before so i'm not really sure what to expect.

AFAIK there are hop oils made from steam distillation of pellet hops, as well as supercritical CO2 extraction. I believe the CO2 stuff is what you normally see as like a HopShot and is used for bittering. It must be boiled.
Click to expand...

interested to see how it tastes
 
Have you used the Hornindal from Omega? I thought it had very nice flavor. It seemed to really attenuate more than I expected though. Have you seen higher than usual attenuation using the kveik strains?

TimmyWit said:
I don't see any reason to rest it at 70. I have pushed all the Omega Kveik strains into the 90's and have been pleased with the results. What did your fermentation schedule look like? I like to give it a few days to clean up after reaching FG. Either that or do a forced diacetyl test to be sure any precursors are gone.

It sounds like you're pulling from the bottom. If you pick up a floating dip tube, you can pressure transfer to a keg with the floating dip tube installed, crash then use that for your SV.

I have not experienced any issues with pressure fermenting the Kveik strains. I have Hothead and Escarpment Labs Hornindal on tap now. They actually got away from me during fermentation, maxed my 60 psi gauges and they're both drinking great (had to bleed them of course).

I feel like Voss has the most farmhouse character of the 3. You'll get a lot of citrus and even a bit of tartness so just a heads up; your final product will probably resemble a saison more than a blonde.
Click to expand...
 
stickyfinger said:
Have you used the Hornindal from Omega? I thought it had very nice flavor. It seemed to really attenuate more than I expected though. Have you seen higher than usual attenuation using the kveik strains?
Click to expand...

As far as attenuation; maybe a bit but nothing too crazy that I recall. I have used Hornindal from Omega and it is very nice. The only one from Omega I haven't tried yet is Jovaru but it is waiting for me in the fridge for my next brew day.
 
I discovered another nifty technique that I've been playing around with, maybe others do this as well but I'll mention it anyway. This may be appealing to you CO2 purists. If you're fully spunding to carb, disregard this post.

I will mention that I cold crash before transfer which seems to be working extremely well with the floating dip tube especially if you transfer under a higher pressure than spund to keep foaming down. I have also gone away from high spunding pressures because of trapping undesirable compounds / dry hopping issues. YMMV on that topic.

So instead of hooking gas-gas and liquid-liquid and starting a siphon, I hook the gas post up on the fermenter to my CO2 cylinder and liquid-liquid up (obviously) and pressure transfer. This way I do not have to move the fermenter after it's been cold crashed. I then open the gas on the cylinder and slowly increase the pressure until the transfer starts. Depending on headspace and spund pressure, you can usually transfer off the entire thing and end up with compressing all that pure CO2 in the serving keg with the beer and either shake to carb or just let it sit. If the pressure gets too high in the serving keg while you're transferring you shake it a bit to absorb the CO2 and continue the transfer. The beer won't be fully carbed using this method but it gets it quite close depending on spunding pressure.

In most instances, this method works so well there is literally nothing left except a dry yeast cake.
 
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Andre3000 said:
I discovered another nifty technique that I've been playing around with, maybe others do this as well but I'll mention it anyway. This may be appealing to you CO2 purists. If you're fully spunding to carb, disregard this post.

I will mention that I cold crash before transfer which seems to be working extremely well with the floating dip tube especially if you transfer under a higher pressure than spund to keep foaming down. I have also gone away from high spunding pressures because of trapping undesirable compounds / dry hopping issues. YMMV on that topic.

So instead of hooking gas-gas and liquid-liquid and starting a siphon, I hook the gas post up on the fermenter to my CO2 cylinder and liquid-liquid up (obviously) and pressure transfer. This way I do not have to move the fermenter after it's been cold crashed. I then open the gas on the cylinder and slowly increase the pressure until the transfer starts. Depending on headspace and spund pressure, you can usually transfer off the entire thing and end up with compressing all that pure CO2 in the serving keg with the beer and either shake to carb or just let it sit. If the pressure gets too high in the serving keg while you're transferring you shake it a bit to absorb the CO2 and continue the transfer. The beer won't be fully carbed using this method but it gets it quite close depending on spunding pressure.

In most instances, this method works so well there is literally nothing left except a dry yeast cake.
Click to expand...

Could you share some pictures to help with the description?
 
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leesmith said:
Could you share some pictures to help with the description?
Click to expand...

Sorry this took so long.
IMG_20181103_170818.jpg


Keep in mind this is just for transferring. I use the same blow through serving keg with spunding value during fermentation. I believe this method of transferring has the following benefits:

-Allows you to cold crash and transfer without moving the fermenter at all. Especially useful with a floating dip tube since the yeast/trub will be nicely compacted and undisturbed.
-Faster transfer than the double connection siphon (though that is still a great method).
-Uses up all that valuable pure CO2 that was created during fermentation.

You effectively don't need the spunding valve on the serving keg while your transfer either as the balance of the cylinder regulator with the compressed CO2 headspace dictates the system pressure.
 
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Andre3000 said:
Sorry this took so long.
View attachment 596899

Keep in mind this is just for transferring. I use the same blow through serving keg with spunding value during fermentation. I believe this method of transferring has the following benefits:

-Allows you to cold crash and transfer without moving the fermenter at all. Especially useful with a floating dip tube since the yeast/trub will be nicely compacted and undisturbed.
-Faster transfer than the double connection siphon (though that is still a great method).
-Uses up all that valuable pure CO2 that was created during fermentation.

You effectively don't need the spunding valve on the serving keg while your transfer either as the balance of the cylinder regulator with the compressed CO2 headspace dictates the system pressure.
Click to expand...

No worries....thanks for posting.
When you cold crash do you hook gas up to the FV to deal with suck back?
 
leesmith said:
No worries....thanks for posting.
When you cold crash do you hook gas up to the FV to deal with suck back?
Click to expand...

Hooking up the gas isn't necessary. As long as you've spunded above atmospheric at 5 psi or so, "suckback" will just result in a small pressure drop of the system due to the cooling and contraction of the headspace CO2. Out of curiosity, I did a quick calc assuming 25% headspace in the fermentation keg, cold crashed from 68-37°F, and it resulted in less than a .1 psi pressure drop in the system.

Edit: Thanks to member Crane for highlighting a caveat/error with this post. I don't cold crash for very long, 24-48 hours. You will definitely experience suckback if you allow the beer to fully dissolve the CO2 at its new cold crashed temperature. See his post below.
 
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I posted this in another thread, thinking that thread was this one.
Anyway, here’s the repost:

Got a plan for dry hopping in the fermentation keg. Put it into play yesterday.

Sanitized a hop sock and some thin nylon thread in a jar of starsan.
Filled sock with dry hop charge (and a stainless bar for weight) and tied it off with the thread.
0A7E05C5-2940-4044-921B-4C24F2FF1154.jpeg


After pitching yeast into keg, I seal it up and pressurize with pure O2, shake it up for a while then vent.

Now I removed the safety valve, removed the lid and fed the thread through the safety valve opening, then reinstalled the safety valve.
8890DEE2-2DFB-403D-BC7A-C3339D563CF0.jpeg


9060D007-7587-43D5-914D-8C9290E9309B.jpeg


I only let the bag down far enough to hang in the air above the beer.
Once fermentation is done, I will quickly pull the safety valve ring, allowing the hop sock to fall to the bottom.
It worked perfectly during the dry runs.

The thread is thin enough that the valve still holds pressure just fine.
Just have to remember to sanitize the thread again (or cut it) before pulling the ring.
 
Andre3000 said:
Hooking up the gas isn't necessary. As long as you've spunded above atmospheric at 5 psi or so, "suckback" will just result in a small pressure drop of the system due to the cooling and contraction of the headspace CO2. Out of curiosity, I did a quick calc assuming 25% headspace in the fermentation keg, cold crashed from 68-37°F, and it resulted in less than a .1 psi pressure drop in the system.
Click to expand...

Thanks for posting this! I was just about to ask what the general pressure drop during cold crashing would be.

Does anyone see any issue with spunding to 8psi during the cold crash and carbonating in the fermentation vessel before (close-system) transferring to a serving keg?
 
Andre3000 said:
Hooking up the gas isn't necessary. As long as you've spunded above atmospheric at 5 psi or so, "suckback" will just result in a small pressure drop of the system due to the cooling and contraction of the headspace CO2. Out of curiosity, I did a quick calc assuming 25% headspace in the fermentation keg, cold crashed from 68-37°F, and it resulted in less than a .1 psi pressure drop in the system.
Click to expand...
Not sure how you did your math, but all the carbonation charts posted all over the internet tend to disagree with your conclusion. In my experience, if I finish fermentation in the upper 60s and at 20-25 psi I will have somewhere between 2.2 and 2.4 volumes of CO2. After cold crashing the pressure drops down to 8-10 psi and maintains the same carbonation level.

If I plug 1.35 volumes of CO2 and 65f into beersmiths carbonation calculator I get 8.38psi. When I keep the volumes of CO2 the same and drop the temperature to 40f, the resulting pressure is 0 psi. If you start with 1.5 volumes of CO2, you will still have 1.37psi after cold crashing. 1.5 volumes of CO2 would require 10.68psi at 65f. So if you start with 8psi before cold crashing you may still experience suck back, but if you start at 10psi you will still have positive pressure after cold crashing which will prevent suck back from happening.
 
crane said:
Not sure how you did your math, but all the carbonation charts posted all over the internet tend to disagree with your conclusion. In my experience, if I finish fermentation in the upper 60s and at 20-25 psi I will have somewhere between 2.2 and 2.4 volumes of CO2. After cold crashing the pressure drops down to 8-10 psi and maintains the same carbonation level.

If I plug 1.35 volumes of CO2 and 65f into beersmiths carbonation calculator I get 8.38psi. When I keep the volumes of CO2 the same and drop the temperature to 40f, the resulting pressure is 0 psi. If you start with 1.5 volumes of CO2, you will still have 1.37psi after cold crashing. 1.5 volumes of CO2 would require 10.68psi at 65f. So if you start with 8psi before cold crashing you may still experience suck back, but if you start at 10psi you will still have positive pressure after cold crashing which will prevent suck back from happening.
Click to expand...

Thank you good sir. You've highlighted a bit of a caveat I should have mentioned and you raise a a very valid point. I did not consider CO2 solubility at all! But I am not cold crashing for a long period of time before I transfer; 24-48 hours. I have never really noticed a pressure drop in that amount of time.

You've got me wondering, how long will it take for it to actually hit 0 psi under my initial assumptions. I think I'll test that.

afro_lou said:
Thanks for posting this! I was just about to ask what the general pressure drop during cold crashing would be.

Does anyone see any issue with spunding to 8psi during the cold crash and carbonating in the fermentation vessel before (close-system) transferring to a serving keg?
Click to expand...
See Crane's post above, as what I initially told you may not be correct in your application. I think the answer you were looking for is what he posted.
 
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