Pressurized Closed Loop Corny Keg Fermenting

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Hannabrew

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-Dry hop before the fermentation is totally complete. I realize its difficult to get a gravity sample from a carboy so visually may be your best bed. This will be around the time the kraussen starts to fall but you still see floaters bubbling around.

-If you're racking at FG then definitely add the priming sugar and wait until fermentation restarts (probably an hour or less). Then rack under CO2 pressure into the purged keg. Try to just barely lift the bung, inject the solution, then cap it back up.

-Get it out of the ferm as quickly as possible. Keep your dry hop to a day or two if you can.

Yeah I did both DH additions during active fermentation.

I will add the priming sugar and give that a try. How much priming solution do you typically use for a 5 gallon batch?

One more thing I'm trying to figure out. I use a blow off tube (1in tube on top of airlock in bung and swivel barb on the other end into pitcher of sanitizer) and when I took a sample last night it obviously sucked up some sanitizer into the tubing (only about a foot or so...nowhere near getting into the carboy).

I'm trying to figure how to get the liquid out of the tubing and get a gas disconnect on without introducing O2.

I was thinking about taking the tubing out of the sanitizer and slightly squeezing the PET carboy while simultaneously screwing on the gas disconnect. Would that work? Anybody have any other ideas?
 
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schematix

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How much priming solution do you typically use for a 5 gallon batch?

Depends on a lot of things. I'd say its approx 75g of sugar to 75g of water. There are calculators out there to tell you how much to use.


One more thing I'm trying to figure out. I use a blow off tube (1in tube on top of airlock in bung and swivel barb on the other end into pitcher of sanitizer) and when I took a sample last night it obviously sucked up some sanitizer into the tubing (only about a foot or so...nowhere near getting into the carboy).

I'm trying to figure how to get the liquid out of the tubing and get a gas disconnect on without introducing O2.

I was thinking about taking the tubing out of the sanitizer and slightly squeezing the PET carboy while simultaneously screwing on the gas disconnect. Would that work? Anybody have any other ideas?

I never could figure out another way.... that's why i went to using kegs under a little bit of pressure. Just attach a short cobra tap and a quick squirt later you've got a sample, and there hasn't been any back flow.

Another idea i had at one point, but never built, was to build a bung assembly with both a gas and liquid dip tube and ports, plus a blow off port. When its sample time, you just close up the blow off port, build some pressure, and then use that to push out the sample via the liquid port.
 

Hannabrew

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Ahhh...I totally missed that you are naturally carbonating. For some reason I was reading it as adding a little priming solution just to create some fermentation to eat the O2 introduced during racking.

How long does it take you to naturally carb a corny?

Have you ever done a hybrid method where you add a little bit of solution to scavenge O2 while also force carbing to speed up the process?
 
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schematix

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How long does it take you to naturally carb a corny?

In my experience it takes a moderate strength ale about a week at room temp. Then you can crash it.... 2 weeks would be more than safe. Few days at cold temps and it's good to go. Make sure to bleed any excess pressure manually or use a spunding valve to automatically release.


Have you ever done a hybrid method where you add a little bit of solution to scavenge O2 while also force carbing to speed up the process?

No. Bottle CO2 even at 99.9% purity is too impure to carbonating with (if low oxygen is your goal). I have also established a sufficiently large pipeline that i'm never in a that big of a hurry. In my experience a beer doesn't hit stride until about 3-4 weeks though... ~1 week ferm, ~1-2 week carbonate, ~1-2 week cold conditioning.
 

Hannabrew

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Well I don't have a spunding built yet (still waiting on a few parts) so I will try the hybrid for this round. Will pitch a bit of priming solution to get some o2 scavenging while simultaneously force carbing all at room temp.

Thanks for all the help and the detailed tutorial!
 

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One more thing I'm trying to figure out. I use a blow off tube (1in tube on top of airlock in bung and swivel barb on the other end into pitcher of sanitizer) and when I took a sample last night it obviously sucked up some sanitizer into the tubing (only about a foot or so...nowhere near getting into the carboy).

I'm trying to figure how to get the liquid out of the tubing and get a gas disconnect on without introducing O2.

I was thinking about taking the tubing out of the sanitizer and slightly squeezing the PET carboy while simultaneously screwing on the gas disconnect. Would that work? Anybody have any other ideas?
Have a look at Jaybird's (NorCal brewing solutions) Krausen catcher tops for Mason jars. With two of them you can have an empty jar between the blowoff and the airlock bubbler jar, which gets flushed with CO2 during fermentation. Then during cold crash or sampling, the empty jar acts as a CO2 reservoir, and any suck back happens by pulling sanitizer from the air lock jar into the empty jar. That way you can have 32 fl oz or more CO2 stored in the blowoff system.

Or you could use a LP propane regulator to put very light CO2 pressure on the fermenter during sampling or cold crash - basically the same as a cask breather for cask conditioned beer. Put it on a valved tee in the blow off tube and you can have a gentle gas flow while you pull and cap the end of the tube from the airlock jar.
 
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schematix

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Well I don't have a spunding built yet (still waiting on a few parts) so I will try the hybrid for this round. Will pitch a bit of priming solution to get some o2 scavenging while simultaneously force carbing all at room temp.

I would highly recommend against this... you are likely to overcarb and oxygenate the batch, which defeats the purpose of going through this effort.

Instead, use a priming calculator to calculate how much sugar you need, then use 3/4 of the suggested amount. Seal the keg up (no spund needed!) and after 7-10 days chill it for a few days then take a sample. If its under carbed, just put it on the gas to finish.
 

Hannabrew

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I would highly recommend against this... you are likely to overcarb and oxygenate the batch, which defeats the purpose of going through this effort.

Instead, use a priming calculator to calculate how much sugar you need, then use 3/4 of the suggested amount. Seal the keg up (no spund needed!) and after 7-10 days chill it for a few days then take a sample. If its under carbed, just put it on the gas to finish.

I was only thinking of putting 2oz of priming sugar in 2oz of water...since it's a closed transfer to begin with I wouldn't think there'd be much to scavenge and then I could use my normal method.

You don't think that would be better than just using my normal method of closed transfer and force carb? I need beer by Thursday so I don't have the luxury of time with this batch.

I figure if I just keep the PSI at serving pressure and I know I'm undershooting the natural carb I can't overcarb right?
 
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I figure if I just keep the PSI at serving pressure and I know I'm undershooting the natural carb I can't overcarb right?

Incorrect. The yeast won't stop natural carbonation just because its at the carbonation level you want. The gas stops when at equilibrium. That's why it's better to do natural first, then top off with the bottle if needed.
 

Hannabrew

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To ensure i understand this correctly, even though I would be using only half the priming solution needed, the issue would be that the force carb comes to equilibrium before natural carb is done and therefore it would potentially overshoot the target right?
 
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schematix

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To ensure i understand this correctly, even though I would be using only half the priming solution needed, the issue would be that the force carb comes to equilibrium before natural carb is done and therefore it would potentially overshoot the target right?

Depends on temperature and pressure, but yes... IF the force carb comes to equilibrium before natural carb is done it will overshoot the target
 
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schematix

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Just goes to show that standard fill-purge-fill-purge purging is practically worthless!
 

Hannabrew

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Due to lack of space, I don't have a fermentation chamber and therefore fermenting in a corny would be tough for me as I can't imagine my normal temp control techniques (swamp cooler/fermwrap) would work with a keg.

However in trying to perfect my closed transfers with my current Fermonster fermenters, I've noticed that they are capable of holding at least 2 psi of pressure without anything giving. My issue has been that I have to babysit it due to a leaky stopper or thermowell.

Therefore I just ordered two new lids from brewhardware that will have a weldless ball lock gas post as well as a weldless 18" thermowell. These should eliminate my leaking issues during closed transfers.

But this got me thinking...could I try to simulate the process schematix outlined in the OP with this setup with some modifications?

Instead of connecting at the 4 hour mark, I would run the first 12 hours or so in normal blowoff fashion (to ensure most O2 is gone from FV), then attach to SV with spunding valve set very low.

I'm thinking this should work as long as I purge my SV with more like 4-5 psi instead of 10 so that when I connect it to the FV there isn't much backflow if any.

If that doesn't work for some reason I'm thinking I could at least ferment under some pressure by attaching the spunding valve directly to the FV and setting it to 2-3psi.

Thoughts? Otherwise we'll see how it goes! Worse case these lids should solve my closed transfer issues.
 

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Due to lack of space, I don't have a fermentation chamber and therefore fermenting in a corny would be tough for me as I can't imagine my normal temp control techniques (swamp cooler/fermwrap) would work with a keg.
Why wouldn't it work? If anything it should work better, because kegs have a better heat transfer than plastic fermenters.
 

Hannabrew

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I just assumed it was double walled and therefore a good insulator but not conductor.

Has anybody tried a swamp cooler with corny kegs with success? I usually also put my fermenters in a dish tub with water that I add ice to periodically. Due to the feet on the kegs it would likely sit above the water too
 

dyqik

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I just assumed it was double walled and therefore a good insulator but not conductor.
Ah, no, kegs (both corny and sanke) have a single, fairly thin, stainless steel wall.

That said, I've just bought a ported Fermonster for closed transfers, because I want to do full 5 gallons into the keg batches.
 

Hannabrew

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Well maybe I'll try it at some point then. I can still use the weldless thermowells to modify my corny lids if I decide to go that route.

And yes that is another concern...I hate not having a full keg.
 

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I just assumed it was double walled and therefore a good insulator but not conductor.

Has anybody tried a swamp cooler with corny kegs with success? I usually also put my fermenters in a dish tub with water that I add ice to periodically. Due to the feet on the kegs it would likely sit above the water too

I do it all the time (got an IPA going now with this method). Works great! For most ales, I just plop the keg in a homer bucket, add cool water, and change it whenever it gets at or above my fermentation temps. For IPAs, I go grain to glass in 1-2 weeks and using LODO kegging have greatly improved my IPAs. I do a lot of them with my Zymatic, so I have 2 or more gallons of headspace in the keg fermenter, which resulted in IPAs that were not drinkable after a few days. Now I have them on tap until they kick with no noticeable staling. Been taking pictures in the same light to compare first glass to last and don't see any noticeable color change. Liking it a lot!
 

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I've had a Kolsch fermenting with this method for the last week or so and I did the transfer to serving keg last night. I had a lot of bubbles in my line (I'm using 3/8" OD line) and my transfer stalled with a lot of beer left in the Fermenting Keg, I had to resort to pushing the rest with bottle CO2.

Presumably line lengths and also height differential between the two kegs are important with this method? I'd guess we want the transfer line to offer as little resistance as possible, contrary to how we want our beer lines to be in a kegerator? Also, the greater the height differential the faster the transfer?
 

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Presumably line lengths and also height differential between the two kegs are important with this method? I'd guess we want the transfer line to offer as little resistance as possible, contrary to how we want our beer lines to be in a kegerator? Also, the greater the height differential the faster the transfer?


I've had great results with a couple of heavily dry hopped IPAs that I've done using this method, which I assume would be a style likely to cause a slow or stalled transfer. I'm using loose pellets in the primary keg and a shortened dip tube (bought a couple of spares that I could trim to different lengths). I do a 24-48hr cold crash for these beers to help the dry hops settle before the transfer. The beer and gas lines I use for the closed transfer are 5/16" ID and height differential is around 4ft.
 
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I've had a Kolsch fermenting with this method for the last week or so and I did the transfer to serving keg last night. I had a lot of bubbles in my line (I'm using 3/8" OD line) and my transfer stalled with a lot of beer left in the Fermenting Keg, I had to resort to pushing the rest with bottle CO2.

Presumably line lengths and also height differential between the two kegs are important with this method? I'd guess we want the transfer line to offer as little resistance as possible, contrary to how we want our beer lines to be in a kegerator? Also, the greater the height differential the faster the transfer?

I have observed something similar in the past and i believe it is related to the differential pressure between the kegs not being sufficient to maintain flow through 2 dip tubes and the hose once the liquid level gets low in the fermenting keg.

To resolve i usually add some additional external pressure to the fermenting keg.
 

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Well, since we're trying to create a closed loop here I think the differential is definitely a factor of height vs resistance in the diptubes/lines. I'm using standard food grade beer line so it'd be interesting to try this with something with less pressure drop per foot, like silicone.
 
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When i rack i do it from a standard stainless prep table, which has a height of about 35". I also use standard bev tubing and i keep it as short as possible, plus a few inches for maneuverability.

The other thing i've noticed is if i let the whole system have a higher pressure, say 5-7 psi, i have fewer issues than when i go low, around 3.5 psi.
 

Hannabrew

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I thought I read somebody talking about this before but now I can't find it.

How would you recommend doing a water/starsan purge of a corny with a bent dip tube?

I realize the OP in this thread talks about only bending the FV dip tube but I bend the SV diptube as well since I am always dry hopping in there. I bend it enough to put a 300micron SS cylinder filter under the dip tube and of course by doing that, I am unable to push out all the water via CO2. I do turn it upside down and drain through the gas in while applying some CO2 through the bev out but since I don't have flush gas dip tubes it doesn't really get it all.

Any other ideas short of getting those dip tubes cut?
 
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Fill all your lid cavities with epoxy. Otherwise when your'e inverted you're going to have 3oz of oxygenated water.

To purge, remove the gas post and gas dip tube. Invert and drain under pressure while slightly tilted towards the gas side. While still inverted and pressure applied, re-install the dip tube and post.
 
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schematix

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Process Change:

I wish i could go back and edit the original post...

I had a suspicion that even tilting the keg to 45 degrees while filling through the liquid port and purging via the gas port wasn't removing all the air. I've confirmed that a small bubble remains in the corner of the lid even doign this.

I would suggest that after doing the 45 degree tilt, and no further bubble sputters are observed, do a >180 degree tilt while still applying purge water, and then slowly tilt back to 45 degrees, before returning to vertical. Keep the gas port on the high side during the tilt. You'll get one last bubble out.
 

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If someone googles for "oxygen permeability of plastics" or similar search terms you will quickly find that silicone has biggest oxygen uptake (it is pretty much breathing) so i'd suggest retiring our silicone keg o-rings and tubing for maximum LODO effect.
 
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schematix

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Anything else, there is a thread here about o-rings (McMaster Keg O-Ring List) they mention Buna-N (nitrile rubber), my tubes are John Guest LLDPE tubes and something called Lupulus II which is for beer tap systems, made of nylon.

Some sources about silicone having the biggest O2 permeability:

page 4.
page 9.

As far as I am aware, keg o-rings are not silicone so those should be ok.

Ideally we'd all stop using corny kegs and move to sanke, but that's not realistic for the home brew market right now.

So I guess your suggestion is specific to the materials used during wort production? Best i can find that LLDPE tubing is only good to 150F, so no good for me.

BTW good links. I hadn't seen that one comparing the different closures before, but i had suspected those results when i moved to corny kegs.. it was a major consideration in fact.
 

The_Glue

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As far as I am aware, keg o-rings are not silicone so those should be ok.

Ideally we'd all stop using corny kegs and move to sanke, but that's not realistic for the home brew market right now.

So I guess your suggestion is specific to the materials used during wort production? Best i can find that LLDPE tubing is only good to 150F, so no good for me.

BTW good links. I hadn't seen that one comparing the different closures before, but i had suspected those results when i moved to corny kegs.. it was a major consideration in fact.

I think the only time this stuff matters is long term storage (fermentation, serving) and probably the small contact area of o-rings with air makes diffusion a non-issue but i have heard about people getting consistently oxidized beer in their tap lines so maybe we should avoid silicon tubes for serving. (my tap line stores about 1/10 litre of beer, but with bigger diameters and longer tap lines for the compensation of the diamter you can easily geet 1-2 litres of beer in there)

I should have worded my first post better, it was more like a general warning for anybody who is interested in eliminating oxygen.
 

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Question.

I have recently got on board with this idea of purging a keg using natural fermentation gas, linked somewhere in this thread. I already had a pressure conical so really I just needed an extra keg for this to happen, which I now have.

So I have the fermentor gas port connected to the sanitised empty keg's liquid port. Spunding valve on the keg's gas port set to 5psi, increasing to 15psi later on. The fermentng batch should get me a properly purged keg by the time I'm ready to do a closed transfer.

Now my second fermentor is not pressurised. I rack into kegs the old-fashioned way then purge the old-fashioned way. I was wondering if I could purge the headspace of this full keg in the same way as the empty kegs? Ie connect it to the pressure fermenting batch and let the natural CO2 purge the headspace and maybe even partially carbonate the keg? I happen to have lagers in the pressure fermentor so maybe some of the CO2 would stay in solution at the cooler temperatures?

I'm thinking someone has surely tried this before, for better or worse :tank:
 

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Your problem is not the volume of CO2 available but the time of exposure via partially purged headspace. Not sure you could carbonate that way.
 

Hannabrew

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Ah, no, kegs (both corny and sanke) have a single, fairly thin, stainless steel wall.

That said, I've just bought a ported Fermonster for closed transfers, because I want to do full 5 gallons into the keg batches.

So while I did get those fermonster lids modded and they work great, I needed an extra fermenter yesterday so I used a corny for the first time.

My question is if blow off gets into the SK, what do you do about it? Just leave it?
 

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