Closed-circuit Fermentor-to-Keg Transfer

[Gustatorian]

Sorry but 0.2ppm is NOT an insignificant amount of O2 according to all published brewing literature.

Like an active fermentation dry Ice is a continuous supply of CO2. The stratification between gasses observed is mostly due to temperature differences.

If by a "Long Time" you mean less than a minute to be WAY above 1ppm then yes.

Mind linking any of this literature?

 

[doug293cz]

Mind linking any of this literature?

Here's my favorite: http://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1540_Darron_Welch.pdf. Look at page 21.

Brew on

 

[doug293cz]

In a confined space, you can create a Blanket of CO2. As far as air mixing when you open the lid, that is true but the bottom of the keg is still full of CO2. 0.1 to 0.2 PPM is an insignificant amount of O2 compared to the 99.9 to 99.8 PPM of CO2. Grain Silos where there is a natural CO2 "blanket", require breathing equipment to enter. You can create a visual blanket with some Dry Ice and water. The CO2 will evaporate and cover the water in a fog. Sure, it goes away, but if you did it in an enclosed contained, it would take a long time.

You can only have a stable blanket (that lasts for more than a few minutes) if you have a continuous source of CO2 generation. The thickness of the blanket will depend on the rate of CO2 generation vs. the rate of air/CO2 inter diffusion. With dry ice and water, what you see is water fog (made up of small water droplets.) CO2 is invisible, just like air. Check the "enclosed container" in this video. Takes only about 30 minutes for Br2, which is 3.6 times heavier than CO2, to completely mix in a totally enclosed system. CO2 is about the same density as the NO2 shown later in the video, which mixes much faster than the Br2.

[ame]https://www.youtube.com/watch?v=_oLPBnhOCjM[/ame]

OSHA requires breathing equipment when the O2 content of the local atmosphere is less than 19.5% (vs. 21% normally). So, that is a meaningless comparison. Likewise, allowable long term exposure limits for humans to CO2 is 0.5%, and max short term limit is 3%, and both are easily exceeded in an enclosed fermentation area. So, too much CO2 for breathing is another meaningless comparison.

Even if you replace 99.9% of the air with CO2 you still have 0.1% air (10,000 ppm) and 0.021% O2 (2,100 ppm.) That's still about 20,000 times too much O2. It doesn't take much O2 to degrade the flavor of beer over time. See page 21 of http://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1540_Darron_Welch.pdf.

Brew on

 

[TexasWine]

You can only have a stable blanket (that lasts for more than a few minutes) if you have a continuous source of CO2 generation. The thickness of the blanket will depend on the rate of CO2 generation vs. the rate of air/CO2 inter diffusion. With dry ice and water, what you see is water fog (made up of small water droplets.) CO2 is invisible, just like air. Check the "enclosed container" in this video. Takes only about 30 minutes for Br2, which is 3.6 times heavier than CO2, to completely mix in a totally enclosed system. CO2 is about the same density as the NO2 shown later in the video, which mixes much faster than the Br2.

https://www.youtube.com/watch?v=_oLPBnhOCjM

OSHA requires breathing equipment when the O2 content of the local atmosphere is less than 19.5% (vs. 21% normally). So, that is a meaningless comparison. Likewise, allowable long term exposure limits for humans to CO2 is 0.5%, and max short term limit is 3%, and both are easily exceeded in an enclosed fermentation area. So, too much CO2 for breathing is another meaningless comparison.

Even if you replace 99.9% of the air with CO2 you still have 0.1% air (10,000 ppm) and 0.021% O2 (2,100 ppm.) That's still about 20,000 times too much O2. It doesn't take much O2 to degrade the flavor of beer over time. See page 21 of http://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1540_Darron_Welch.pdf.

Brew on

This is exactly why I love Doug's posts.

 

[Carlscan26]

Even if you do that, you still have about 3 fl oz of liquid trapped because of the lid design.



View attachment 360548



View attachment 360549



Brew on

That's still far less than not flipping it over. Also if you leave it attached to the CO2 and shake it around I'd imagine you could get another ounce or two out...especially if you stop and let pressure build up before you open the PRV. Also, I doubt that 1-3 oz of starsan would make any noticeable difference in a five gallon batch of beer.

 

[doug293cz]

That's still far less than not flipping it over. ...

Did you measure this? If not, how do you know?

... Also, I doubt that 1-3 oz of starsan would make any noticeable difference in a five gallon batch of beer.

I agree with you on this.

Brew on

 

[Carlscan26]

Did you measure this? If not, how do you know?

I'm not going to cut any of my dip tubes to be 1" from the bottom of the keg but it's reasonable to assume that the remaining volume is definitely more than 3 oz right?

This is an impossibility for me due to my liquid-out tubes being cut about an inch above the bottom of the keg. I fear that I'd leave too much sanitizer at the bottom of my keg and it would water-down or create a strange flavor within my beer.

 

[doug293cz]

I'm not going to cut any of my dip tubes to be 1" from the bottom of the keg but it's reasonable to assume that the remaining volume is definitely more than 3 oz right?

For a dip tube cut 1" from the bottom, yes (I didn't realize you were talking about that case.) For an unmodified dip tube, I'm not so sure.

Brew on

 

[day_trippr]

If an unmodified oem dip tube is properly positioned in the small well at the bottom of the keg, it's only going to leave a couple of tablespoons of fluid (if that) when totally blown out...

Cheers!

 

[jddevinn]

Mind linking any of this literature?

Gustatorian,

The majority of the literature I am talking about is not available for linking as they are physical textbooks.

• Technology Brewing and Malting, Kunze
• A Textbook of Brewing, J. DE CLERCK
• Brewing Science and Practice
• The Role of Oxygen in the Brewery (this one is a link) http://www.ibdlearningzone.org.uk/article/search/?searchstring=yeast&category=22&author=&keyword=
  
  These books give both recommendations and chemical reasons for the changes due to oxygen.
  
  From Brewing Science and Practice
  
  Preventing air getting into the beer [during packaging} is essential. All the precautions followed in producing bright beer must be maintained. The final product specification for dissolved oxygen in teh beer will be <0.2mg/l [same as 0.2ppm], in some cases, <0.1mg/l, so during filling operations the pickup of oxygen must not exceed 0.02-0.03mg/l [0.02-0.03ppm]. if this oxygen level is not achieved serious flavour deterioration will result.
  
  ...
  
  Roughly 1 ml of air in a 300ml bottle will give an oxygen content of 1ppm, wich is probably enough to oxidize all the reductiones present in a light lager beer.
  

 

[Braufessor]

Just listened to one of the 2016 conference seminars on oxidation...... if you think it is depressing trying to figure out how to eliminate oxygen pick up transferring from fermenter to keg.... Give this a listen (if you can access it without being an AHA member???). You will be ready to give up entirely.

He talks about the impact of oxidation at every phase. The most depressing part is when he talks about the introduction of oxygen during the mash and the fact that enough oxygen is introduced in standard mashing processes to be well over the threshold. Big production breweries are actually going to nitrogen flushed mash tuns.

At that point I just thought.... well, that is never going to happen on the homebrew level.

https://www.homebrewersassociation....on16 - Identifying and Avoiding Oxidation.mp3

To be honest, while I acknowledge that the "industry standard" for oxygen in beer is very, very low. I don't think there are any home brewers achieving that over the course of their entire process. And, if some are, it is a tiny, tiny piece of a single percentage.

I would be curious if at some point there is simply a threshold that is above industry standard, but below what 90%+ beer drinkers can ever really notice as a detrimental effect in their beer. Basically, if no one can taste a certain level of a "problem", is it actually a problem?

With that said, everyone should take as much care as they can not to introduce oxygen - especially at the points they can control. I like the tip someone mentioned about turning the keg upside down and venting out the CO2 post to get the last bit of star san out in a keg with a short tube (I use one for dry hopping sometimes). Filling the keg with star san and pushing out with CO2 is absolutely the way to go - simple, efficient, effective.

 

[user 141939]

Maybe this is a dumb question. If you're filling a closed keg through the liguid out, how do you know when to stop? Since you can't see the level at all.

 

[TexasWine]

Maybe this is a dumb question. If you're filling a closed keg through the liguid out, how do you know when to stop? Since you can't see the level at all.

Well, you could use one of these.

https://www.ballandkeg.com/

Or, what I started doing was putting a known amount of wort in the fermenter and leaving a known amount behind. I'll put 5.5 gallons in, and I know where to set my rotating dip tube to have exactly 0.75 gallons left behind. 4.75 gallons to the fermenter every time.

 

[jddevinn]

Maybe this is a dumb question. If you're filling a closed keg through the liguid out, how do you know when to stop? Since you can't see the level at all.

I fill the kegs off the fermenter at the same time using a manifold. Once the beer starts coming out of the PRV (with NPT fitting and hose barb) or the gas out (that has a QDC) I pull the QDC off of that keg.

 

[doug293cz]

Maybe this is a dumb question. If you're filling a closed keg through the liguid out, how do you know when to stop? Since you can't see the level at all.

If you are transferring cold beer to the keg, you can just watch the condensation line on the outside of the keg (might not work so well during winter if outside or in unheated garage, or if the humidity is very low.)

Brew on

 

[vance]

Just listened to one of the 2016 conference seminars on oxidation...... if you think it is depressing trying to figure out how to eliminate oxygen pick up transferring from fermenter to keg.... Give this a listen (if you can access it without being an AHA member???). You will be ready to give up entirely.

He talks about the impact of oxidation at every phase. The most depressing part is when he talks about the introduction of oxygen during the mash and the fact that enough oxygen is introduced in standard mashing processes to be well over the threshold. Big production breweries are actually going to nitrogen flushed mash tuns.

At that point I just thought.... well, that is never going to happen on the homebrew level.

https://www.homebrewersassociation....on16 - Identifying and Avoiding Oxidation.mp3

To be honest, while I acknowledge that the "industry standard" for oxygen in beer is very, very low. I don't think there are any home brewers achieving that over the course of their entire process. And, if some are, it is a tiny, tiny piece of a single percentage.

I would be curious if at some point there is simply a threshold that is above industry standard, but below what 90%+ beer drinkers can ever really notice as a detrimental effect in their beer. Basically, if no one can taste a certain level of a "problem", is it actually a problem?

With that said, everyone should take as much care as they can not to introduce oxygen - especially at the points they can control. I like the tip someone mentioned about turning the keg upside down and venting out the CO2 post to get the last bit of star san out in a keg with a short tube (I use one for dry hopping sometimes). Filling the keg with star san and pushing out with CO2 is absolutely the way to go - simple, efficient, effective.

I thought oxygen during mashing was a good thing?

 

[mongoose33]

I fill the kegs off the fermenter at the same time using a manifold. Once the beer starts coming out of the PRV (with NPT fitting and hose barb) or the gas out (that has a QDC) I pull the QDC off of that keg.

That must leave almost no headspace--how easy or how long is it to carbonate something like that?

 

[mongoose33]

If you are transferring cold beer to the keg, you can just watch the condensation line on the outside of the keg (might not work so well during winter if outside or in unheated garage, or if the humidity is very low.)

Brew on

I racked (closed circuit) to a keg last night, and that's exactly what I did--watched the rising condensation line on the keg.

 

[jddevinn]

That must leave almost no headspace--how easy or how long is it to carbonate something like that?

Depending on the method I'm using:

1. My "default" carbing method is to use a keg with an additional QDC added to the middle of the lid. Carb stone is attached to this QDC and carbing is done in 2-3 days, headspace doesn't matter I then transfer to another keg to serve.
2. IF I want to force carb "normally" I'll put pressure on the keg then hook a picnic tap to the gas in and pour beer out (or more realistically drink) down to the bottom of the gas in pickup. Oversizing batches by a gallon or two helps still end up with full kegs.
3. I've started experimenting with natural carbing with a spunding valve. In this case headspace doesn't matter.

 

[jddevinn]

I also remembered back when I used to fill one keg at a time I'd calculate the weight of 5 gallons of that gravity beer, place the keg on my grain scale, tare and then fill until I got the weight of 5 gallons before switching kegs.

 

[mongoose33]

Depending on the method I'm using:

1. My "default" carbing method is to use a keg with an additional QDC added to the middle of the lid. Carb stone is attached to this QDC and carbing is done in 2-3 days, headspace doesn't matter I then transfer to another keg to serve.
2. IF I want to force carb "normally" I'll put pressure on the keg then hook a picnic tap to the gas in and pour beer out (or more realistically drink) down to the bottom of the gas in pickup. Oversizing batches by a gallon or two helps still end up with full kegs.
3. I've started experimenting with natural carbing with a spunding valve. In this case headspace doesn't matter.

Ahhh....I wondered if you were doing something like that. How hard or easy is it to clean and sanitize that carb stone? I've liked that idea since I first read about it.

Other question, maybe not appropriate here: last night when i was force carbing, I turned the pressure up to 30psi, then rocked the keg. I could of course hear the gas bubbling in as I rocked the keg, but my problem is that I have no way to tell if I overcarb it. I want it to serving pressure of 10-12 PSI, and it's clear that if I kept rocking the keg, at some point I'd have gotten higher than 10-12.

Is there way with a spunding valve to determine pressure? In other words, I'd carb at high pressure, then remove the gas QD, shake some more until I was at a presumed equilibrium, then attach a spunding valve w/ a pressure gauge to check?

 

[jddevinn]

Ahhh....I wondered if you were doing something like that. How hard or easy is it to clean and sanitize that carb stone? I've liked that idea since I first read about it.

Honestly, I haven't had any issues.. however, I don't really like that I added NPT fittings to the inside of my keg. It was the best "brite tank" I could come up with at the time however. Basically this but DIY. SSbrew is coming out with a bright tank and I expect if it sells well others will follow.

I end up filling the keg with sanitizer solution, putting the lid (due to the NPT parts) and the stone into boiling water for about 10-15 minutes, putting on the keg and attempting to get out all of the air bubble then pushing the sanitizer out. When I clean out the keg I blow some CO2 through the stone to make sure it is dry.

Other question, maybe not appropriate here: last night when i was force carbing, I turned the pressure up to 30psi, then rocked the keg. I could of course hear the gas bubbling in as I rocked the keg, but my problem is that I have no way to tell if I overcarb it. I want it to serving pressure of 10-12 PSI, and it's clear that if I kept rocking the keg, at some point I'd have gotten higher than 10-12.

Lots of people go over pressure and "burst" carb. I don't like to do this as there is a good chance to overshoot your target carbonation level. You should select your pressure based on the temperature and carb volumes that you are serving at. You can carb quicker by holding the keg at a lower than serving temperature and using the corresponding pressure. Most of the beer styles I make are too green at this point anyway and I sit on the kegs for weeks before serving.[/QUOTE]

Is there way with a spunding valve to determine pressure? In other words, I'd carb at high pressure, then remove the gas QD, shake some more until I was at a presumed equilibrium, then attach a spunding valve w/ a pressure gauge to check?

You wouldn't need a spunding valve for this, just a pressure gauge on a QDC. The spunding valve is basically a pressure relief valve, so if I set it to say 20psi it will maintain the pressure at 20psi... if it goes above it'll bleed back down to 20psi.

I wouldn't put too much effort into this. If you need 12psi for your carbonation level you can set at 12psi and shake, you're not going to get much quicker absorption by setting to 30psi.

 

[Gustatorian]

I sit my kegs on a scale. 50 pounds of fluid is almost 5 gallons in the keg. That's how I know when to stop transferring.

 

[user 141939]

I sit my kegs on a scale. 50 pounds of fluid is almost 5 gallons in the keg. That's how I know when to stop transferring.

This sounds easiest to me I suppose I'll buy scale.

 

[TexasWine]

This sounds easiest to me I suppose I'll buy scale.

Digital luggage scale is another option you might consider.

 

[jddevinn]

I use this scale as my grain scale. I used to use it with kegs, they fit almost perfectly on the surface.

 

[popquizkid]

The scale is a great idea and something that I have never thought of.

I almost always cold crash before transfer which makes it pretty easy to see where the fill level is as water condensates on the outside and you can also put your hand ont he side of keg and tell where the fill line is by temperature.

 

[Gustatorian]

The scale is a great idea and something that I have never thought of.

I almost always cold crash before transfer which makes it pretty easy to see where the fill level is as water condensates on the outside and you can also put your hand ont he side of keg and tell where the fill line is by temperature.

I don't cold-crash but I need to start. The condensation thing sounds like a solid idea. I guess you could also tap on the side of the keg to hear the different tympanic sounds it would make between liquid and no liquid...never tried it though.

 

[jddevinn]

The scale is a great idea and something that I have never thought of.

I almost always cold crash before transfer which makes it pretty easy to see where the fill level is as water condensates on the outside and you can also put your hand ont he side of keg and tell where the fill line is by temperature.

Depends on the transfer rate When I positive pressure transfer the keg can get filled in a couple minutes... the condensate line always lags behind due to the the (small) thermal mass of the keg walls.