Keg elevation during fully closed-loop transfer between kegs

[CyberFox]

Here's a scenario:
I have a keg that I fermented in (kegmenter) and a receiving keg that I need to transfer to.
I would like to do a fully closed-loop transfer between the kegs.
Let's say that I have the kegmenter pressurized to 10 psi and the receiving keg to 8 psi.
I attach liquid-to-liquid and gas-to-gas transfer lines between the kegs to start the transfer.

I have two questions:
1) Will the 2 psi difference between kegs be enough to transfer from one keg to the other if they're both on level ground or will I need to elevate the kegmenter above the receiving keg? If I need to elevate the kegmenter, by how much?

2) Does it matter which order I attach the transfer lines to the kegs (gas or liquid first)?

Thanks in advance!

 

[TheMadKing]

Here's a scenario:
I have a keg that I fermented in (kegmenter) and a receiving keg that I need to transfer to.
I would like to do a fully closed-loop transfer between the kegs.
Let's say that I have the kegmenter pressurized to 10 psi and the receiving keg to 8 psi.
I attach liquid-to-liquid and gas-to-gas transfer lines between the kegs to start the transfer.

I have two questions:
1) Will the 2 psi difference between kegs be enough to transfer from one keg to the other if they're both on level ground or will I need to elevate the kegmenter above the receiving keg? If I need to elevate the kegmenter, by how much?

2) Does it matter which order I attach the transfer lines to the kegs (gas or liquid first)?

Thanks in advance!

I'm pretty sure the beer and gas pressure will just equilibrate between the two kegs on level ground and you won't get a transfer.

Just elevate the kegmenter so that the bottom is level with the top of the receiving keg.

Better yet, use CO2 to just push from your kegmenter and vent the excess pressure on the receiving keg.

 

[CyberFox]

Okay, that's what I was wondering: if the kegs would equilibrate on level ground and stop the transfer. Good to know.

I was originally planning on doing what you described (using CO2 to push and exhausting the receiving keg), but I was considering my original strategy because it would save CO2 and I've heard that venting would let aroma from the dry hop escape. If that's true, I have no idea.

If using my original strategy, does it matter how much higher I elevate the kegmenter's bottom over the top of the receiving keg (say 2+ feet above)?

 

[brewbama]

I lay down my receiving keg on a 2x4 on edge so it sits at a slight angle but below the bottom of the fermenter.

 

[IslandLizard]

does it matter how much higher I elevate the kegmenter's bottom over the top of the receiving keg (say 2+ feet above)?

That's fine, higher will give you a bit more gravity push on the transferring beer.

Once the (gravity) siphon starts, you can likely vent the CO2 from the receiving keg back into the kegmenter. The CO2 pressure will even out between the 2 vessels, but the gravity fed siphon should continue. I've never tried it with both vessels being pressurized, though.

 

[Bassman2003]

This is how I do pressurized transfers. Gravity fed is better as it is slower which keeps more CO2 in solution. I have the receiving keg hooked up through the entire fermentation so it gets purged with pure CO2 from the yeast. Gas out of the fermenter to Liquid in on the keg. Gas out of the keg to a spunding valve via a Gas to Gas line. Spunding valve out to water for an airlock.

When it is time to transfer after a cold crash I leave the Gas out line connected to the keg and unhook the other end from the spunding valve. (The line is purged of air since it has been hooked up the entire time). I then get my Liquid to Liquid line and connect it to the fermenter Liquid out and put the other side on a Kegland "T" fitting. This allows me to run the first bits into a 2-liter bottle, purging the line from air as well as running any picked up sediment into the 2-liter. The 2-liter bottle is brought up to the same PSI via a CO2 tank (other side of the "T") and the small transfer is made. Once this is completed I push a male to male connector in the open end of Gas to Gas line to bleed 1-2 PSI out of the keg. I then hook up the liquid line from the fermenter first, then the gas post back to the fermenter to complete the circle. It takes a while but it is totally closed, so you do not need to baby it.

The goal is minimal O2 pickup, clear beer and keeping as much CO2 in solution as possible. Putting the receiving keg in the fridge a few hours before helps as well if your beer has been cold crashed.

Sorry to the long message. It is simpler in practice! I plan on making a video about it soon.

 

[CyberFox]

This is how I do pressurized transfers. Gravity fed is better as it is slower which keeps more CO2 in solution. I have the receiving keg hooked up through the entire fermentation so it gets purged with pure CO2 from the yeast. Gas out of the fermenter to Liquid in on the keg. Gas out of the keg to a spunding valve via a Gas to Gas line. Spunding valve out to water for an airlock.

When it is time to transfer after a cold crash I leave the Gas out line connected to the keg and unhook the other end from the spunding valve. (The line is purged of air since it has been hooked up the entire time). I then get my Liquid to Liquid line and connect it to the fermenter Liquid out and put the other side on a Kegland "T" fitting. This allows me to run the first bits into a 2-liter bottle, purging the line from air as well as running any picked up sediment into the 2-liter. The 2-liter bottle is brought up to the same PSI via a CO2 tank (other side of the "T") and the small transfer is made. Once this is completed I push a male to male connector in the open end of Gas to Gas line to bleed 1-2 PSI out of the keg. I then hook up the liquid line from the fermenter first, then the gas post back to the fermenter to complete the circle. It takes a while but it is totally closed, so you do not need to baby it.

The goal is minimal O2 pickup, clear beer and keeping as much CO2 in solution as possible. Putting the receiving keg in the fridge a few hours before helps as well if your beer has been cold crashed.

Sorry to the long message. It is simpler in practice! I plan on making a video about it soon.

No worries about a long message. That's really good info! It would be awesome to see a video of your process. I haven't seen any videos on this specific subject.

I was planning to start using CO2 from fermentation to purge the receiving keg too. I figured it might be a good thing to not vent the keg during transfer, but I have no idea if it actually results in lost aroma. Some say it does and others say that if the aroma's in the headspace already, then it wasn't actually in the beer in the first place.

Seems like every time I learn something about homebrewing, I have something else to figure out! How long does your transfer take?

 

[DuncB]

@CyberFox
Your original plan will work.
Higher the better and larger diameter liquid line speeds it up.
No need to force with extra CO2 at all.
It takes about half an hour so be prepared to walk away.

Regarding order connect liquid lines first.siphon should start as pressure difference then gas

Do remember to have purged both lines prior to this procedure.
Liquid line purge from receiving keg and gas either way.

I routinely Purge starsan filled keg with ferment gas and closed transfer as discussed.
You asked for video

 

[Bassman2003]

It is a bit complicated but not too bad. I never pull the PRV and try to do any kind of bleeding though a tube/spunding valve if possible. O2 gets in so quickly and easily that one has to anal about it on the cold side. I have a lager going now and will try to document the whole process and update this thread in a week or two.

 

[jerrylotto]

PV = nRT. In other words pressure is an inverse function of volume at a constant temperature and amount of gas. As you transfer liquid from one keg to another the gas volume in the source keg is increasing and the gas volume in the destination keg is decreasing, so consequently the pressure in the destination keg will rise unless the gas lines are connected. In that case, the overall gas volume remains constant so the pressure just equalizes and you're doing a simple siphon. You can see what height difference you need simply by leaving the whole system open and observing water siphoning from one keg to the other

 

[CyberFox]

Awesome. You guys have confirmed things for me and given me some good tips. I appreciate it!

 

[Tommydee]

You definitely need to vent the keg. Letting it bleed is ok if transfer is constant. using a low set spund on the outlet is not a good idea for a carboy, unless you can pressurize it more than 3-4 psi, or you’ll have same issue. Please be very careful with these closed transfer carboy kits if using glass…NEVER use anything to tighten the orange carboy cap, consider it a safety near miss if that thing pops off, and never allow more than 1-2 psi. I personally am terrified of pressurizing glass, but more terrified of oxygen in beer…so with the BHW carboy cap, i still put the carboy elevated above the keg to enable gravity transfer. I fully purge the keg with the starsans displacement method. I bleed the keg just before transfer. I initiate the transfer very carefully with 1-2 psi on the fermenter and the keg prv open, then once i have a siphon, close the prvI quickly connect a CO2 purged jumper line to the keg gas post, then take the other end and swap it with your CO2 source on the fermenter. Now you are gravity racking with CO2 from the keg displacing the beer from the fermenter. Closed system, no risk of glass shrapnel, uses less CO2.

 

[jerrylotto]

You definitely need to vent the keg. Letting it bleed is ok if transfer is constant. using a low set spund on the outlet is not a good idea for a carboy, unless you can pressurize it more than 3-4 psi, or you’ll have same issue. Please be very careful with these closed transfer carboy kits if using glass…NEVER use anything to tighten the orange carboy cap, consider it a safety near miss if that thing pops off, and never allow more than 1-2 psi. I personally am terrified of pressurizing glass, but more terrified of oxygen in beer…so with the BHW carboy cap, i still put the carboy elevated above the keg to enable gravity transfer. I fully purge the keg with the starsans displacement method. I bleed the keg just before transfer. I initiate the transfer very carefully with 1-2 psi on the fermenter and the keg prv open, then once i have a siphon, close the prvI quickly connect a CO2 purged jumper line to the keg gas post, then take the other end and swap it with your CO2 source on the fermenter. Now you are gravity racking with CO2 from the keg displacing the beer from the fermenter. Closed system, no risk of glass shrapnel, uses less CO2.

If you put a second hole in your stopper and put it to the gas in port on your keg, you wouldn't need to pressurize the carboy at all just get a siphon going.

 

[CyberFox]

You definitely need to vent the keg. Letting it bleed is ok if transfer is constant. using a low set spund on the outlet is not a good idea for a carboy, unless you can pressurize it more than 3-4 psi, or you’ll have same issue. Please be very careful with these closed transfer carboy kits if using glass…NEVER use anything to tighten the orange carboy cap, consider it a safety near miss if that thing pops off, and never allow more than 1-2 psi. I personally am terrified of pressurizing glass, but more terrified of oxygen in beer…so with the BHW carboy cap, i still put the carboy elevated above the keg to enable gravity transfer. I fully purge the keg with the starsans displacement method. I bleed the keg just before transfer. I initiate the transfer very carefully with 1-2 psi on the fermenter and the keg prv open, then once i have a siphon, close the prvI quickly connect a CO2 purged jumper line to the keg gas post, then take the other end and swap it with your CO2 source on the fermenter. Now you are gravity racking with CO2 from the keg displacing the beer from the fermenter. Closed system, no risk of glass shrapnel, uses less CO2.

More terrified of oxygen in beer than exploding glass. That got me. Us crazy homebrewers! I can relate.

That's a good technique you have, but after all the horror stories I've read about a glass carboy just falling apart in someone's hands and cutting through their tendon(s), I've had no interest in glass. I've used a plastic carboy from the beginning and now I'm moving on to a keg for fermentation. I know you already know, but be damn careful with glass!

 

[jerrylotto]

More terrified of oxygen in beer than exploding glass. That got me. Us crazy homebrewers! I can relate.

That's a good technique you have, but after all the horror stories I've read about a glass carboy just falling apart in someone's hands and cutting through their tendon(s), I've had no interest in glass. I've used a plastic carboy from the beginning and now I'm moving on to a keg for fermentation. I know you already know, but be damn careful with glass!

As do I - having the dump valve at the bottom of the fermenter makes gravity transfer simple.

 

[segallis]

I have the receiving keg hooked up through the entire fermentation so it gets purged with pure CO2 from the yeast. Gas out of the fermenter to Liquid in on the keg. Gas out of the keg to a spunding valve via a Gas to Gas line. Spunding valve out to water for an airlock.

I've seen this posted on multiple threads. The best way to properly purge and assure nothing but CO2 remains is to have the keg filled with starsan and then purge via the gas line in, allowing all the liquid to flow out the dip tube side. If the keg starts with air in it, then running CO2 through it has the potential to leave O2 behind as the CO2 will mix with the air. True the longer the flow of CO2 in terms of time and total volume, the lower the O2 concentration should be, but going in the liquid side should not be much different from going the gas side, since "stratification" is not much of a factor, and CO2 and air will mix. In theory, the fermentaiton will release maybe 110 gallons of CO2, which if mixed uniformly in the keg, could reduce the O2 level to around 1% (*based on 4 kg CO2 per hl of beer). Maybe that is good enough? On the other hand, a single 5 gal purge of starsan with CO2 totally eliminates all O2.
The article referenced below made things clear.

 

[day_trippr]

Keg purging with active fermentation

We all know fermentation produces 100% pure CO2 gas -- wouldn't it be great to use it for purging a keg without pushing water out first? Others have shown smart things like purging a serving keg with a fermenting keg. I know there's a fixed relationship of CO2 production to sugar consumption...

www.homebrewtalk.com

Cheers! (And have fun with that )

 

[jerrylotto]

I've seen this posted on multiple threads. The best way to properly purge and assure nothing but CO2 remains is to have the keg filled with starsan and then purge via the gas line in, allowing all the liquid to flow out the dip tube side. If the keg starts with air in it, then running CO2 through it has the potential to leave O2 behind as the CO2 will mix with the air. True the longer the flow of CO2 in terms of time and total volume, the lower the O2 concentration should be, but going in the liquid side is no different from going the gas side, since "stratification" is a non-factor, and CO2 and air will simply mix. In theory, the fermentaiton will release maybe 110 gallons of CO2, which if mixed uniformly in the keg, could reduce the O2 level to around 1% (*based on 4 kg CO2 per hl of beer). Maybe that is good enough? On the other hand, a single 5 gal purge of starsan with CO2 totally eliminates all O2.

See the 2018 article KEGGING WITH CARE: A GUIDE TO PURGING on the another site (blocked for posting on homebrewtalk) for a good discussion of the topic. It is a lot more complicated than stated above. If you search for the title it is the first hit you get.

 

[Bassman2003]

Both methods are really good and one should choose either to be at the top of homebrew cold side practice outside of a unitank.

I lean towards the keg purging because it is easier and the CO2 is pure from the yeast. Since I ferment under pressure or at least spund, when it is time to transfer the keg is already there with a purged line ready to just be hooked up. I sanitize the keg on brew day right along side my fermenter.

 

[segallis]

See the 2018 article KEGGING WITH CARE: A GUIDE TO PURGING on the another site (blocked for posting on homebrewtalk) for a good discussion of the topic. It is a lot more complicated than stated above. If you search for the title it is the first hit you get.

Thanks for the article! That clears things up regarding slow and steady purging. I had incorrectly thought of the 110 gals of CO2 produced as a single dilution of the original O2 concentration, rather than as a bubble by bubble continuous dilution. Makes sense. (Although that analysis appears identical regardless of whether you go into the gas or liquid port).

 

[BongoYodeler]

Transferring now. Seems to be working fine, albeit a bit slow. That's fine though, I'm retired.

 

[DuncB]

Transferring now. Seems to be working fine, albeit a bit slow. That's fine though, I'm retired.

View attachment 812743

Yes it is slower than youtube would have you believe.

If you can get some larger diameter liquid tubing that will help the transfer speed.

 

[BongoYodeler]

Yes it is slower than youtube would have you believe.

If you can get some larger diameter liquid tubing that will help the transfer speed.

As I said, I'm retired so I'm not in a rush. The transfer is finished, probably took between 45-60mins. I did pour off a little 3 oz. sample and it's filled with micro bubbles. While fermenting I used a spunding valve, set to 10 psi, and also have to use a pulley/hoist to lift the keg into and out of the keezer, but the transfer was slow and gentle. Hopefully things settle down. I just hit it with a syringe of gelatin....that was an adventure.

 

[Broken Crow]

Yes it is slower than youtube would have you believe.

If you can get some larger diameter liquid tubing that will help the transfer speed.

I recently upgraded all my bulk-transfer lines to 3/8" Bevelx 200... As long as you have no carbonation whatsoever, you and get 15-30% better speed, but even the slightest bit of foaming will slow it down to the point of negating any speed benefit. I'm still glad I went to the larger diameter, and I'd recommend it to anyone starting on this path, particularly for the lower O2 permeability and longevity of the lines themselves. If you're habit is pressure fermenting, you won't see a lot of speed-of-transfer benefit, but for what most of us do, it is definitely worth it.

EDIT: Oh yeah; In order the 3/8" Bevlex be worth it, I also attached it to the CM Becker diconnects with a 3/8" barb rather than the usual 1/4" MFL, as both the poppet and the internal path of the disconnect, while they don't come near a 3/8" ID, still is greater than 1/4"

 

[DuncB]

I just hit it with a syringe of gelatin....that was an adventure.

I add the finings before the transfer so that i know they get well mixed in. No need to lift the keg and shake it that way.

 

[BongoYodeler]

I add the finings before the transfer so that i know they get well mixed in. No need to lift the keg and shake it that way.

Thanks, I guess I could do that. But would you still cold crash, or just rely on the gelatin for dropping everything out? In order for me to cold crash I have to move the keg from in the house to out in the garage. Then use a pulley/gambrel to lift the keg up and into the keezer to cold crash. After a couple days I lift it back out and set it down on the top of the keezer (see my pic above). All that movement is surely mixing things back up inside the keg. The other option is cold crashing but then using my CO2 tank to transfer the beer to the serving keg. The positive to that is no movement since the serving keg can also be in the keezer. The negative is using my tank CO2 to move beer rather than ferment CO2. I may have to rethink this whole fermenting in a keg, as I didn't have these issues when fermenting in my Speidel.

 

[DuncB]

I cold crash my fermenting vessel then add the finings ( to the receiving keg) just before the closed transfer and then keep the keg cold whilst it fines.