Pressurized Closed Loop Corny Keg Fermenting

[schematix]

Here are some pictures. One thing to clarify is that I do not use the same method of closed loop gravity/siphon transfer that the OP uses. I tried it a few times and it would always stop half way through. I think there is too much restrictions in my lines and disconnects that slows the transfer down and stops.

The same thing happens to me sometimes.

I think what is happening is that there is not a sufficient pressure differential between the 2 tanks to overcome the restriction from the 2 liquid dip tubes plus the 2 QDs plus the liquid tubing once the level in the FV starts to drop. In other words, the pressure exerted by the siphon is no longer enough once the higher tank level drops, and the lower tank level rises.

I've tested 2 different solutions, and both worked about the same:
1. If you are have enough pressure stored up (say >5 psi), burp the SK's PRV to give it a lower pressure relative to the FV.
2. Add external CO2 pressure to the FV. For me it only took a few seconds of gas to kickstart it.

If you could create a larger vertical displacement you could also help yourself.

There may be something else going on here because the gas-gas jumper should in theory equalize the head pressure, but I've clearly had situations where it wasn't.

 

[oujens]

This is great. I have a beat up keg for cheap that has a plastic air dip tube that would fit the bill for this. I was actually thinking of spending $ on a fermentation vessel to have the closed transfer ability. Already got the liquid dip tube shaped. Just curious, how much volume is in the bottom of a keg? I'm assuming fermenter loss of .5 gallons. To me even if I don't get 5 gallons in the SK, having a better shelf life on 4.5 gallons is worth it. Especially when I don't have to invest in other equipment!

 

[schematix]

Just curious, how much volume is in the bottom of a keg?

It depends how far the dip tube is shortened / bent. Mine has only about 1/4 gallon of dead space.

 

[oujens]

It depends how far the dip tube is shortened / bent. Mine has only about 1/4 gallon of dead space.

Yep, probably should have specified but I guess it's easy to measure out some water to see where the dip tube is hitting. Duh!

 

[schematix]

Yep, probably should have specified but I guess it's easy to measure out some water to see where the dip tube is hitting. Duh!

That's what i did.... put in about half a gallon of watter then push it with a few psi until it's blowing air, then dump the rest into a measuring cup.

I actually find i have more dead space than i need for most beers so when i'm racking if i get to the end and i'm not sucking sludge i'll tilt the keg about 10 degrees. I probably get another glass or two that way.

 

[oujens]

That's what i did.... put in about half a gallon of watter then push it with a few psi until it's blowing air, then dump the rest into a measuring cup.

I actually find i have more dead space than i need for most beers so when i'm racking if i get to the end and i'm not sucking sludge i'll tilt the keg about 10 degrees. I probably get another glass or two that way.

Sweet, look forward to testing this out. Is there ever a time you would consider using a blowoff before attaching the SK to the FV? Are you able to control the krausen for ales and lagers using pressure and nothing else?

 

[schematix]

Sweet, look forward to testing this out. Is there ever a time you would consider using a blowoff before attaching the SK to the FV? Are you able to control the krausen for ales and lagers using pressure and nothing else?

Always add fermcap.

I am considering using a blow-off tube for the beer i'm making this weekend. I am doing a 1.057 pale ale and fermenting in the mid 60s. If i do that, it'll only be there for a day or two until the kraussen stops pumping out, then i'll switch to the purge/spund configuration.

I've had a mix of experiences so far.

I've had really good success with moderate OG lagers (1.050), fermented cold (48F), under about 5 psi. These peaked around 1cm of kraussen. Those never sent any blow off into the jumpers. Not even a drop.

I've had several ales fill the head space (~3") entirely with kraussen, and of those, only about half actually sent kraussen through the jumper tube. I surmise it has to do with how good the head retention of the beer was.

I've had 2 lagers, both that were nearly 1.060, also send kraussen through the jumper tube, although both were also fermented at 50F.

 

[Inkleg]

Always add fermcap.

How much do you normally add?

 

[schematix]

How much do you normally add?

1 drop per gallon. I might add another couple for insurance if i put too much in the keg.

 

[thekraken]

@schematix, with your mcmaster prv about how many turns per pound?

I finally put mine into service yesterday for the first time and forgot to figure this out myself before hand.

Also, is it critical that the SV be attached during fermentation or will just the water purge you described with the co2 tank be adequate?

 

[schematix]

@schematix, with your mcmaster prv about how many turns per pound?



I finally put mine into service yesterday for the first time and forgot to figure this out myself before hand.



Also, is it critical that the SV be attached during fermentation or will just the water purge you described with the co2 tank be adequate?

One thing I don't like about the McMaster prv is the lack of an indicator. It seems to be about 1 psi per turn, but I've never measured. I always set it via the guess and check method. Since I have a pressure gauge attached to mine it's easy to figure out. I start high and dial it back.

As far as keeping the SK attached, it depends. If you're doing a really great water purge (defined by getting the air bubble out under the lid), then I'd say no. But I do use it also to protect the prv from blow off. It'll need to be connected before the end though to build up some pressure and be equalized to the FV so that you can rack without applying external co2.

 

[thekraken]

One thing I don't like about the McMaster prv is the lack of an indicator. It seems to be about 1 psi per turn, but I've never measured. I always set it via the guess and check method. Since I have a pressure gauge attached to mine it's easy to figure out. I start high and dial it back.

I do have a gauge on mine too, but when you make adjustments to increase pressure during fermentation how fast does it build up? I just assumed the build up of pressure would happen more slowly than what I'd have patience to sit and watch... I guess I'm about to find out. I did set it initially by over pressurizing the line with a co2 bottle and dialing it back to where I wanted it before I put it on the fermenter.

(edit)
Sorry, I forget you use ~3.5psi through the whole fermentation. I keep confusing you with the guys at WortMonger's thread that like to use pressure schedules.

 

[schematix]

I do have a gauge on mine too, but when you make adjustments to increase pressure during fermentation how fast does it build up? I just assumed the build up of pressure would happen more slowly than what I'd have patience to sit and watch... I guess I'm about to find out. I did set it initially by over pressurizing the line with a co2 bottle and dialing it back to where I wanted it before I put it on the fermenter.

(edit)
Sorry, I forget you use ~3.5psi through the whole fermentation. I keep confusing you with the guys at WortMonger's thread that like to use pressure schedules.

Depends on how active the fermentation is and how far of a step it is. If i'm trying to dial in 0.5 psi early in the fermentation process it's stable after 15 minutes.

Cool trick i found if you need to bleed a keg a little bit is to gently put your finger over the PRV outlet. Pressure will build and as long as you let some escape, but not all, it'll continue to vent.

 

[thekraken]

This is my first attempt at this process. I put an airfilter housing in line to catch blowoff instead of a SV as I didn't have room for another keg in the fermentation fridge, good thing I did because I woke up this morning and the housing was nearly full and blowoff was bubbling up toward the prv.

Relevant stats for other newbies:
1.051 OG pale ale
nottingham dry yeast (not rehydrated)
65F
I'm guessing was filled to the weld (hard to tell through the starsan foam)
5 psi
10 drops of fermcap
I have not yet shortened the gas tube

One thing learned is that I may need to use a non-foaming sanitizer in the fv from now on because starsan's foam makes it impossible to see what my fill level is inside the corny... It was my first brew on a shiny new system so there was a lot of gettin to know each other on this brew day, I haven't got a sight glass yet and the dead space volumes, boiloff, etc were just guesses so I didn't have much of a reference point for when the keg was at the right level.

 

[schematix]

I just kegged a hoppy pale ale last night. I let it go to terminal gravity (took 9 long days). I injected approx 60g of dextrose (in liquid form) into each keg 1 hour prior to transfer to SK in order to ensure active fermentation to scavenge any O2 picked up.

Vitals:
OG: 13.6 P
FG: 4.1 P
Yeast: Wy1450. Pitched active.
Pressure: 10 psi
Temperature: 62F for first 48 hours, then increased 1F per day.
Fermcap: 5 drops
Beer level: 1" below weld
Kraussen ring: 1"
Blowoff result: None

 

[thekraken]

Pressure: 10 psi

Aha! So you do vary from 3.5 psi. How do you decide what pressures you want to use for a particular brew?

How did you inject the dextros solution? Using the method @DaWhip described in post #21?

 

[schematix]

Aha! So you do vary from 3.5 psi. How do you decide what pressures you want to use for a particular brew?

How did you inject the dextros solution? Using the method @DaWhip described in post #21?

This was the first time i varied pressure intentionally. My last 2 beers had an unusual amount of blow off (more than zero) and I wanted to contain it because i was tired of cleaning the disconnects and hoses. I can't speak to the benefit of this other than to say i've never had an ale fermentation with less than 3-4" of kraussen, and this one stopped at 1".

I injected the dextrose using a 100mL syringe. I put the keg under external pressure from a tank (~8 psi), unscrewed the PRV, injected it, then re-installed the PRV. I've seen another method that coupled the syringe right to a gas QD and shot the solution right in through the gas port. I'll probably get the fittings to do that next time because it'll be easier and i won't have to connect external CO2.

 

[duelerx]

schematix can you give more details on how you dry hop with the last SG points remaining?, Do you first disconnect the FV to the SK so you won't introduce any oxygen when you add the hops?

 

[schematix]

schematix can you give more details on how you dry hop with the last SG points remaining?, Do you first disconnect the FV to the SK so you won't introduce any oxygen when you add the hops?

1. Disconnect SK from FV (otherwise you'll back flow all your purge gas)
2. Attach external CO2 source to FV, 5-10psi is fine. this will help to maintain positive pressure.
3. Open PRV on FV to relieve pressure.
4. Remove lid.
5. Insert dry hops through lid. You can use a bag or stainless canister. Do not free ball them or you will clog the poppet. I tie my bag to the lid using a ring clamp on the PRV and some fishing line.
6. Re-install lid.
7. Tighten PRV
8. Purge head space a few times (it's not going to be perfect but that's why we're doing this with remaining gravity.
9. Reconnect SK and FV.
10. A few days later inject priming solution into FV. Wait until fermentation restarts, then rack as usual.

 

[duelerx]

I was just checking NorCal Solution website and there is an option to add a gas in with pressure relief valve and a NPT male dip tube and thermowell for Speidels fermenters, i see Speidels fermenters as a big advantage over Keg with its size. I already have some Speidels fermenters so i will take a shot with these accessories and the close loop technique.

 

[schematix]

I was just checking NorCal Solution website and there is an option to add a gas in with pressure relief valve and a NPT male dip tube and thermowell for Speidels fermenters, i see Speidels fermenters as a big advantage over Keg with its size. I already have some Speidels fermenters so i will take a shot with these accessories and the close loop technique.

That'll make racking easier but those fermenters can't hold much pressure.

i think the corny makes a good fermenter for what it is.... a cheap, stainless, pressure capable vessel. It certainly has its flaws though.

 

[duelerx]

That'll make racking easier but those fermenters can't hold much pressure

That's a good point.

 

[Hoppity]

Subbed, going to try this.

 

[thekraken]

Thanks Schematix and DaWhip!

I was curious if there was a way to use gelatin as I like clarifying my beers.

I'll check out the threads mentioned.
Thanks again!

^ Bumping this question ^

@Schematix, do you use gelatin and cold crash the SV after it's carbed up? Or are we worried about the yeast being too inactive at this point to scrub any O2 that might be introduced with the gelatin addition?

 

[schematix]

^ Bumping this question ^

@Schematix, do you use gelatin and cold crash the SV after it's carbed up? Or are we worried about the yeast being too inactive at this point to scrub any O2 that might be introduced with the gelatin addition?

I get very clear beer without any additives so i don't use them.

However, if i were to add gelatin, i'd add it to the FV (not the SK) and i'd treat it like dry hopping. With gravity points remaining, inject it via the PRV under positive pressure, or if you are more handy, via the gas port.

If you are out of gravity points, add them in the form of some priming sugar.

 

[cheesebach]

There are some great suggestions in this thread - it's given me some things to think about and try with my setup. I did have a question though that I haven't seen addressed yet in this thread. What is the reason for doing a water purge instead of sanitizer in the SV? Are people doing this using tap water to fill/purge, and wouldn't this create a risk for infection?

Also, I had a comment/suggestion for those contemplating bending the dip tube - Austin Homebrew Supply sells straight dip tubes in both 20" and 21" lengths for $5 each. I've bought 1 of each size and they both seem like good options, depending on the amount of trub you usually get in your process. For 5 bucks, you get to keep your original dip tube, and get one that will already be sitting above the trub line with no bending or cutting involved. Also, since they are straight, they'll be close to the side of the keg near the bottom so you could easily tilt near the end of the transfer to get those last few ounces of clear beer out.

 

[schematix]

I did have a question though that I haven't seen addressed yet in this thread. What is the reason for doing a water purge instead of sanitizer in the SV? Are people doing this using tap water to fill/purge, and wouldn't this create a risk for infection?

The reason for water vs sanitizer purge is mainly due to cost. That's 1oz star san per keg, which approaches a dollar each. The odds of getting an infection in fermented beer from chlorinated tap water is incredibly low.

Note i do thoroughly clean and will often do a star san rinse prior to the water purge if i suspect anything. Most of the time i'm turning kegs around pretty quick. My empties are stored cold and i don't crack them open to clean until right before i clean and purge them again.

 

[thekraken]

Also, if you happen to have another empty keg around you can use it to push a little starsan in the SV, swirl it around, and push it back out. Just be careful to first purge the jumper line of air and stop the starsan transfer before you push any air into the SV.

 

[acidrain]

Also, if you happen to have another empty keg around you can use it to push a little starsan in the SV, swirl it around, and push it back out. Just be careful to first purge the jumper line of air and stop the starsan transfer before you push any air into the SV.

You would be using Co2, not air.

Edit: never mind... misread the post and see that you would correctly not want the air in the line to get in the vessel.

 

[RoatanBill]

Ingenious!

Subscribed so I can find it again when I'm ready for it.