Pressurized Closed Loop Corny Keg Fermenting

[hezagenius]

Brand new kegs seal really well. Wish I had never bought used ones. Not worth the hassle.

Damn straight. I ordered some "lightly used" kegs from one of the most common keg suppliers for homebrewers and they looked like they were run over by tanks. From now on, I just buy new AEB kegs. Awesome build quality and I don't have to worry about mixing up lids, posts and poppets.

 

[vtipsy]

One question about purging with fermentation C02 - should I see the jar of sanitizer bubble up, like a normal airlock would? This is connected to the serving keg via a quick disconnect attached to the gas out post.

I see bubbles like you do in an airlock.

Also, if you filled up a large column of water or starsan for the output, you could increase the pressure in the kegs.

1 psi is equivalent to 27.7 inches of water.

 

[stickyfinger]

I see bubbles like you do in an airlock.



1 psi is equivalent to 27.7 inches of water.

That's why I usually fill up a bucket with mercury. ha ha ha

 

[vtipsy]

That's why I usually fill up a bucket with mercury. ha ha ha

That would work. What could possibly go wrong.

 

[chieftain]

I see bubbles like you do in an airlock.



1 psi is equivalent to 27.7 inches of water.

Hmmm. Cause I'm not seeing them. This is my first time using an SS conical, so it should be more airtight than my previous big mouth bubbler.

 

[vtipsy]

Check the connections and figure out where that C02 is going because it's got to be going somewhere. Could be a loose lid.

Or maybe the fermentation is lagging or stalled.

 

[chieftain]

Check the connections and figure out where that C02 is going because it's got to be going somewhere. Could be a loose lid.

Or maybe the fermentation is lagging or stalled.

Turns out it was a loose hose barb...had the wrong size for the tube I was using. Doh! Fixed that, and it started bubbling right away. Awesome! Thanks

 

[Andre3000]

Can some one explain the need for the priming sugar during transfer?

If the "dilution game" holds true for o2 then the reverse is also true and there should be little to no o2 remaining in the serving keg with the water purge and all the co2 from fermentation if you're spunding through it.

Then if that's true, should you be able to ramp the pressure up at the end of fermentation and carb from that alone?

 

[stickyfinger]

I think there are at least 3 reasons for using priming sugar:

a) too lazy to do a forced ferment test and then pressurize right around 4-5 pts left (could just up the pressure anytime, but not everyone wants to ferment under higher pressure I presume)

b) you miss the time period to ramp up pressure due to the beer dropping really fast or whatever else goes on in life so you need more food for more CO2 (as appears to have happened on my first attempt at spunding a saison!)

c) you want to add dry hops at the same time as ramping up the pressure and don't really want any of the gas to escape so it needs to be pretty close to the right amount of CO2 production left to carbonate the keg

 

[stickyfinger]

OK, so I just tried my first closed fermentation. It has gone off pretty well so far! I filled a keg pretty full with saison wort with the yeast added as it was filling, oxygenated, sealed it up and put on a blowoff. At 24 hrs or so from pitch it was thumping away and no blowoff, so I attached a sanitized keg (not purged, as I didn't have enough gas left in my cylinder (great timing) and set it to spund at around 4 PSI. I came back around 12 hrs later and it was at around 4 PSI slowly hissing from the valve, awesome.

I came back about 12 hrs later again and the pressure has already dropped to maybe 3 PSI and there is not leaking gas, so I took off the valve. I guess it is done fermenting!? I didn't realize my fermentations were happening so fast!

So, I only got maybe 24 hrs of purging of my serving keg, and now I don't have any fermentables left to carbonate. So, my plan is to hope I got enough purging of my serving keg, add priming sugar to through the keg PRV, purge headspace, let rest for a few hours, then hook up to the serving keg and let it transfer over, hopefully with a few points of sugar left to scrub some O2 from the serving keg.

 

[Andre3000]

I think there are at least 3 reasons for using priming sugar:

a) too lazy to do a forced ferment test and then pressurize right around 4-5 pts left (could just up the pressure anytime, but not everyone wants to ferment under higher pressure I presume)

b) you miss the time period to ramp up pressure due to the beer dropping really fast or whatever else goes on in life so you need more food for more CO2 (as appears to have happened on my first attempt at spunding a saison!)

c) you want to add dry hops at the same time as ramping up the pressure and don't really want any of the gas to escape so it needs to be pretty close to the right amount of CO2 production left to carbonate the keg

Ok. If I dry hop it's usually a biotransform happening on day one leaving ample time for fermentation to remove o2. I've yet to try of dry hopping right at yeast pitch but this certainly would merit it.

What's the best way to add the priming sugar? Seems like a royal PITA. I imagine you could push it with another keg? Anyone out there doing this with great success without priming sugar?

 

[stickyfinger]

Ok. If I dry hop it's usually a biotransform happening on day one leaving ample time for fermentation to remove o2. I've yet to try of dry hopping right at yeast pitch but this certainly would merit it.

What's the best way to add the priming sugar? Seems like a royal PITA. I imagine you could push it with another keg? Anyone out there doing this with great success without priming sugar?

schematix recommended a very low pressure purge of the headspace with a co2 cylinder while using a 100 mL syringe to inject the soln through the PRV. I plan to try it soon.

 

[Andre3000]

schematix recommended a very low pressure purge of the headspace with a co2 cylinder while using a 100 mL syringe to inject the soln through the PRV. I plan to try it soon.

The PRV on the spunding valve? Or the PRV on the top of the keg. Most of my kegs dont have the latter.

 

[stickyfinger]

The PRV on the spunding valve? Or the PRV on the top of the keg. Most of my kegs dont have the latter.

the keg PRV. maybe you could crack the lid and inject it while purging?

 

[Andre3000]

the keg PRV. maybe you could crack the lid and inject it while purging?

Yeah. Or I was thinking a valve with a nipple on a disconnect through the gas post may work.

 

[schematix]

Its preferred to inject the priming solution into the fermenter first, but if you're already in the serving keg this is what you can do:

1. Make your priming solution. Boil for at least 5 minutes. Use a little more water than you normally would to accoutn for boil off.
2. Put in ice bath (we want to perform this procedure as quickly as possible so the priming solution doeesn't pick up O2 from the air.)
3. Apply bottle CO2 pressure to keg via gas post. Maybe 3-5 psi... enough to get flow.
4. Relieve pressure and unscrew PRV. You should immediately feel gas coming out - if not, crank up pressure.
5. Draw in required amount of priming solution into large 100mL syringe.
6. Insert syringe into PRV hole. NOTE: be sure you have hold of the plunger so it doesn't rocket backwards towards you.
7. Force priming solution in.
8. Reinstall PRV.
9. Allow keg to minimally pressurize so the lid seats.

Then monitor the pressure.

I don't install my spund valve at all unless i hit target pressure because it has a very slow leak, which prevents carbonation over many days. I normally only attach it for a few hours, or at most overnight, at a time so i don't lose all my pressure when fermentation winds down.

 

[stickyfinger]

Its preferred to inject the priming solution into the fermenter first, but if you're already in the serving keg this is what you can do:

1. Make your priming solution. Boil for at least 5 minutes. Use a little more water than you normally would to accoutn for boil off.
2. Put in ice bath (we want to perform this procedure as quickly as possible so the priming solution doeesn't pick up O2 from the air.)
3. Apply bottle CO2 pressure to keg via gas post. Maybe 3-5 psi... enough to get flow.
4. Relieve pressure and unscrew PRV. You should immediately feel gas coming out - if not, crank up pressure.
5. Draw in required amount of priming solution into large 100mL syringe.
6. Insert syringe into PRV hole. NOTE: be sure you have hold of the plunger so it doesn't rocket backwards towards you.
7. Force priming solution in.
8. Reinstall PRV.
9. Allow keg to minimally pressurize so the lid seats.

Then monitor the pressure.

I don't install my spund valve at all unless i hit target pressure because it has a very slow leak, which prevents carbonation over many days. I normally only attach it for a few hours, or at most overnight, at a time so i don't lose all my pressure when fermentation winds down.

is the 75g of priming sucrose enough to pressurize the serving keg and carbonate the beer to 2 vols or so? I was planning on injecting the priming solution to primary with purging, let rest a few hours or so to scrub some O2 and get yeast activity to build a little pressure in both kegs and then transfer to the serving keg. (my serving keg is only at maybe 3 PSI after primary fermentation.)

 

[schematix]

is the 75g of priming sucrose enough to pressurize the serving keg and carbonate the beer to 2 vols or so? I was planning on injecting the priming solution to primary with purging, let rest a few hours or so to scrub some O2 and get yeast activity to build a little pressure in both kegs and then transfer to the serving keg. (my serving keg is only at maybe 3 PSI after primary fermentation.)

there are calculators out there that'll tell you... you're in the ball park, but it all depends upon the remaining sugar and the current/max temperature the batch has been exposed to.

 

[Andre3000]

there are calculators out there that'll tell you... you're in the ball park, but it all depends upon the remaining sugar and the current/max temperature the batch has been exposed to.

Can you comment if a guy can get away without the priming sugar racket?

 

[schematix]

you can do without the priming sugar if the beer isn't done fermenting yet.

 

[Hannabrew]

The syringe method works nicely if there's no pressure in the vessel you're adding the solution to. FWIW, I have been using a pet bottle with a carb cap with interior barb and tubing cut to length to get my solutions into pressurized vessels with minimal 02.

Sanitize everything
Boil and quickly cool and water you are using
Add solution to pet bottle
Loosely attach carb cap with co2 attached and allow it to purge the bottle.
Once you feel it is sufficiently purged, tighten cap and pressurize to about 10-15 PSI higher than the receiving vessel
Attach jumper cable from carb cap to receiving vessel's gas post and watch it suck up the liquid.

 

[Andre3000]

The syringe method works nicely if there's no pressure in the vessel you're adding the solution to. FWIW, I have been using a pet bottle with a carb cap with interior barb and tubing cut to length to get my solutions into pressurized vessels with minimal 02.

Sanitize everything
Boil and quickly cool and water you are using
Add solution to pet bottle
Loosely attach carb cap with co2 attached and allow it to purge the bottle.
Once you feel it is sufficiently purged, tighten cap and pressurize to about 10-15 PSI higher than the receiving vessel
Attach jumper cable from carb cap to receiving vessel's gas post and watch it suck up the liquid.

Fantastic idea. How much pressure can a pop bottle handle? Haha

 

[schematix]

Fantastic idea. How much pressure can a pop bottle handle? Haha

More than you’d think... easily 100-150 psi. That’s why 2L bottles are great for making dry ice or draino “bombs”.

Even aluminum cans can hold an incredible amount of pressure.

 

[crane]

The syringe method works nicely if there's no pressure in the vessel you're adding the solution to. FWIW, I have been using a pet bottle with a carb cap with interior barb and tubing cut to length to get my solutions into pressurized vessels with minimal 02.

Sanitize everything
Boil and quickly cool and water you are using
Add solution to pet bottle
Loosely attach carb cap with co2 attached and allow it to purge the bottle.
Once you feel it is sufficiently purged, tighten cap and pressurize to about 10-15 PSI higher than the receiving vessel
Attach jumper cable from carb cap to receiving vessel's gas post and watch it suck up the liquid.

Do you purge the 2L bottle by squeezing it to get the air out first or do you leave the cap loose to blow CO2 through the bottle for a bit?

 

[Hannabrew]

Do you purge the 2L bottle by squeezing it to get the air out first or do you leave the cap loose to blow CO2 through the bottle for a bit?

Both. I usually use the smallest bottle possible just so there's less 02 to purge. A decent quality cheap flat bottomed water bottle works best in my opinion.

 

[BeerFst]

Just read through this entire thread, having just attempted my first closed transfer earlier this week. It didn't go well. While clearly a cardinal sin, i was fermenting in my brew bucket, and attempted a closed transfer to a star san purged keg (i didn't get all the bubbles out of the posts, but didn't think about just adding more solution as mentioned on page 1 here). While running, i stopped getting flow, even though i had the PRV opened and thought it was hydro-static pressure overcoming gravity, but that is not the case after reading through here. (i really should have known 27.7"/PSI considering i am a mechanical engineer, but i haven't had to do hydro-statics for the past 10 years and that was in school). Anyway im thinking it was a clog now.

I am going to start fermenting in a corny next batch and will try a modified version of what is described here. But i did have one question. Why push the water with C02 from a tank? Why not just use the pressure generated during ferm to push out the water? a full keg of water ends up being ~2PSI hydro-statically right? so its basically a spund until you push all the water out, no?

 

[thekraken]

...Anyway im thinking it was a clog now.

Been there, done that. Had to remove the post and run a brush through the dip tube a couple times. I try not to forget my hop spiders and and hop bags now. If you're racking from a bucket to a keg's out post it's a good idea to put a filter on the end of the racking cane to keep the hops out of it, also put a SS washer inside the filter to keep the filter itself from collapsing and clogging. @day_trippr has pictures of a good example of this here.

I am going to start fermenting in a corny next batch and will try a modified version of what is described here. But i did have one question. Why push the water with C02 from a tank? Why not just use the pressure generated during ferm to push out the water? a full keg of water ends up being ~2PSI hydro-statically right? so its basically a spund until you push all the water out, no?

I had the same thought, I might try it. I actually asked OP this same question a long time ago, I think the answer was that it really isn't wasting much gas at all to just push the water out and CO2 is cheap.

 

[BeerFst]

and CO2 is cheap.

its not really the cost of the C02 its just annoying to go get a swap, especially since the best place to do isn't open convenient times.

on the filter, i really didnt think it would end up being that much of problem with the bucket, but i was clearly wrong. I do have one of the utah biodiesel filters that Janish recommends and will be using that in the FV for sure. It's still in the box, and i had not soaked it in oxy yet, so i just went without. While this was my first NEIPA and first time going through the dip tube, I had never had problems before so i was just over confident. Next batch is gonna be a blonde without DH, so while i may not need the filtration it will be a good dry run on the new process.

 

[schematix]

I had the same thought, I might try it. I actually asked OP this same question a long time ago, I think the answer was that it really isn't wasting much gas at all to just push the water out and CO2 is cheap.

OP here...

The end requirement is that the keg is purged of air as much as possible.

Filling with water (or sanitizer) and pushing with tank CO2 will get you about 99.9% there. I do this currently because it's easy for me. I have a 20lb CO2 tank i use for everything except serving that i get it refilled about once a year at my LHBS. But i understand not everyone has the same situation.

Another alternative is to route the fermentation gases through the serving keg. I typically do a combination of both, but plan to go to using just fermentation gases eventually.

Right now i fill my kegs so full that blow off is inevitable. I just haven't built something to catch the kraussen while allowing the gasses through. For now i just wait until blow off subsides, then connect the FV to SK to continue purging the water purged keg.

 

[thekraken]

As long as you filter the hops from the brew kettle when transfering to the FV and use a hop sock with dry hops you should be good. Just no free floating hops in the fermenter.