# Keg Force Carbing Methods Illustrated

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#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
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I agree with @day_trippr . At 30 psi gauge (44.7 psi partial) pressure of helium you could get about 0.005 g/L of helium dissolved at 34°F, that's a bit less than 0.0025 g/pint. At atmospheric pressure, 0.0025 g of helium is only 14 ml of He, about 3 teaspoons or 1/2 fl oz.

After you pour the beer, the He will come out of solution very quickly, and end up in the head. In order to get the "helium voice" effect, you would then have to inhale the head. (If you try that, you are more likely to spit than swallow ) If that doesn't choke you to death, there's still probably not enough He to give you the voice.

Brew on

#### Steve Gambrell

##### Member
Hmmmm Perhaps you could look up Berkshire Brewing and their Helium IPA. I've brewed a lot of beer during my time in this hobby. I've gathered lots of equipment and the knowledge to use it all. I have built my own beer refrigerator entirely from discarded scrap bits, and being it was a project beyond what a DIY guy should know most of those who have seen it are in total awe! To sum it up I'm quite able, perhaps more than most and even though this endeavor seems out of reach to most I'm anxious to tackle it. The only pediment I can see is their process employs Liquid helium as opposed to the gas. If using "liquid" helium is tantamount to the success of this project I'm likely out of luck. I don't have much lab equipment but some yes.

#### Steve Gambrell

##### Member
I agree with @day_trippr . At 30 psi gauge (44.7 psi partial) pressure of helium you could get about 0.005 g/L of helium dissolved at 34°F, that's a bit less than 0.0025 g/pint. At atmospheric pressure, 0.0025 g of helium is only 14 ml of He, about 3 teaspoons or 1/2 fl oz.

After you pour the beer, the He will come out of solution very quickly, and end up in the head. In order to get the "helium voice" effect, you would then have to inhale the head. (If you try that, you are more likely to spit than swallow ) If that doesn't choke you to death, there's still probably not enough He to give you the voice.

Brew on
Well Thanks Doug, it was kind of you to respond with at least some interest!

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
Hmmmm Perhaps you could look up Berkshire Brewing and their Helium IPA. I've brewed a lot of beer during my time in this hobby. I've gathered lots of equipment and the knowledge to use it all. I have built my own beer refrigerator entirely from discarded scrap bits, and being it was a project beyond what a DIY guy should know most of those who have seen it are in total awe! To sum it up I'm quite able, perhaps more than most and even though this endeavor seems out of reach to most I'm anxious to tackle it. The only pediment I can see is their process employs Liquid helium as opposed to the gas. If using "liquid" helium is tantamount to the success of this project I'm likely out of luck. I don't have much lab equipment but some yes.
Another well executed April Fools prank (published a day early, 3/31/15).
.

Brew on

#### day_trippr

##### "This Space For Rent"
Some folks just don't - or won't - understand fizzix...

Cheers!

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
Fizzix: a subset of physics that describes the processes involved in the carbonation of beverages.

Brew on

#### day_trippr

##### "This Space For Rent"
You caught that nicely

#### Alex4mula

##### Well-Known Member
I have to say I'm not a fan of the whole high pressure shake and bake way. For me the results were, at best, inconsistent. The last time I did it the results were over foamed, undercarbed beer. Force carbonation is not about force it is about dissolving a certain volume of CO2 into the liquid. The pressure used is determined by the temperature of the liquid. The high pressure shake is crude to say the least. For less then \$50 you can turn any corney keg into a bright tank and carb with reliability and consistency. With accurate feedback to know when you are done. First you'll need one of these:

The tiny bubbles of gas coming out of the stone more quickly dissolve into the liquid. The difference between this way and high pressure shaking is like the difference between dissolving 4oz of powdered sugar verses trying to dissolve a 4oz cube of sugar.

The feedback is measured using a simple pressure gauge that's monitoring the head pressure in your keg. This is what I put together for less then \$15

View attachment 570379

Here is the stone

View attachment 570380

Here's what it looks like together:

View attachment 570381

Here's the link that explains how to use these to carb your beer with confidence.

https://chme.nmsu.edu/files/2016/06/Brite-tank-carbonation.pdf

I've done two beers and each one is dead on perfect. The best part is, they were both carbed in just two days including the 24 hours for the CO2 to 'stick.' The final pressure was 13-14 psi with a wetting pressure of 2 psi for a volume being around 2.5 at 34º F. The kegs are not tall enough for hydrostatic pressure to be much of factor. Maybe a half a psi.

Cheers!
Glad to find posts like this. Built the gauge, followed process and the carbonation on my first brew came out perfect. Thanks Matthew!

#### budaboff

##### Well-Known Member
I've always been a natural carb at room temperature for 2 weeks kind of guy. I'll put 30 PSI to seal the keg. Release the pressure and set regulator to 10ish for serving. I've noticed some of my IPAs lose their aroma/flavor after about a week in the keg and have read that force carb may limit this effect.

My plan is to rack at room temperature, seal the keg at 30 PSI in the kegerator over night, then set and forget the regulator to match my desired carb level.

2 questions: Will the initial 30 PSI sealing pressure impact the overall carb schedule? Should I purge the initial pressure before I set and forget? The second question would allow me to pour a few pints of undercarb beer while waiting.

Thoughts?

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
I've always been a natural carb at room temperature for 2 weeks kind of guy. I'll put 30 PSI to seal the keg. Release the pressure and set regulator to 10ish for serving. I've noticed some of my IPAs lose their aroma/flavor after about a week in the keg and have read that force carb may limit this effect.

My plan is to rack at room temperature, seal the keg at 30 PSI in the kegerator over night, then set and forget the regulator to match my desired carb level.

2 questions: Will the initial 30 PSI sealing pressure impact the overall carb schedule? Should I purge the initial pressure before I set and forget? The second question would allow me to pour a few pints of undercarb beer while waiting.

Thoughts?
How are you purging the air/oxygen from the headspace prior to beginning the actual carbonation process?

Brew on

#### budaboff

##### Well-Known Member
How are you purging the air/oxygen from the headspace prior to beginning the actual carbonation process?

Brew on
I just put 30 psi to seal the keg while it chills overnight. Tomorrow should I release the pressure and set the regulator to 10 for 2 weeks or can I leave the pressure on until done

#### budaboff

##### Well-Known Member
How are you purging the air/oxygen from the headspace prior to beginning the actual carbonation process?

Brew on
By pulling the release valve

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
By pulling the release valve
A proper purge requires multiple pressurize and vent cycles. At 30 psi, each pressurize/vent cycle removes approximately 2/3 of the O2 and N2 that were in the headspace. If you don't purge the keg of air prior to filling the keg, then the headspace starts out at 200,000 ppm of O2. To prevent premature oxidation of the hop components (which kills the hop aromas and taste), total packaged O2 needs to be kept under 1 ppm. This is why I asked about your purge protocol. If you do have excess O2 in your headspace, that could be the reason that your IPA's are not holding up more than a week or two.

To really protect your IPA flavors and aromas you should look into liquid purging and closed transfer when kegging. Lots of pertinent threads in the Kegging/Bottling forum.

Brew on

#### applescrap

##### Be the ball!
What's a simple good pre purge practice Doug? Thanks so much for all the help and knowledge. I have heard fill the keg with water and purge. What if you dont want to do that. Can gas be shot in and purged and work? Honestly just need to splash out for the big bubbler and get a closed transfer set up for the lid.

I have been shooting gas in, purging, racking, and popping with 30 psi 30x, think I got the idea for number of purges from an earlier post by you, although I dont think the number is right. Ultimately, I rarely if ever have anything around long enough that I am to worried, but I am at the point that I can no longer not worry about at least a minimum of cold side oxidation.

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
What's a simple good pre purge practice Doug? Thanks so much for all the help and knowledge. I have heard fill the keg with water and purge. What if you dont want to do that. Can gas be shot in and purged and work? Honestly just need to splash out for the big bubbler and get a closed transfer set up for the lid.

I have been shooting gas in, purging, racking, and popping with 30 psi 30x, think I got the idea for number of purges from an earlier post by you, although I dont think the number is right. Ultimately, I rarely if ever have anything around long enough that I am to worried, but I am at the point that I can no longer not worry about at least a minimum of cold side oxidation.
Unfortunately, there is simple and there is good, and they are separate things in the case of oxygen minimization. If you keep your beer cold and consume it quickly, then oxidation is unlikely to be an issue, unless you make very hoppy beers. Folks who make hoppy beers have reported drastic degradation of hop flavors (with associated beer darkening) after just one or two weeks in the keg, which means oxidation is an issue for them.

You do need to at least some purge cycles after filling (if you don't liquid purge and closed transfer) in order to get the air out of the head space so that the CO2 pressure is the same as what you read on the gauge. For example if the chart says you need 12 psi to get the carb level you want, and you start with air in the head space and pressurize to 12 psi, you only have 12 psi CO2 in the head space along with 14.7 psi of air. The chart assumes that the head space is 100% CO2, so when the gauge reads 12 psi you actually have 12 + 14.7 = 26.7 psi CO2 absolute pressure, which is what you need to get the carb you want. So, if you didn't purge enough air out of the head space, you end up with flat or under carbed beer.

Shooting gas into the keg will displace some of the air, but the problem is you have no idea how much air is left, so results are completely unpredictable..

If you are happy with how your carbonation comes out, and your beer tastes ok to you until the keg kicks, you don't need to change anything. All of the process intricacies are offered for folks, who are not getting results acceptable to them, as ways they can improve their results.

Brew on

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#### IslandLizard

##### Progressive Brewing
Staff member
Mod
I have been shooting gas in, purging, racking, and popping with 30 psi 30x,
I did some calculations on how much CO2 is required to reduce the O2 in the headspace to a reasonably low level (<5-10 ppm O2). With a full keg, leaving 1 quart of headspace you can follow @doug293cz's table or graph, CO2 usage is not exorbitant, but you're not avoiding O2 exposure during the transfer.

Now the picture changes drastically when there is a larger headspace, a partially filled keg. Even with a fill level of 4 gallons, leaving around a gallon of headspace, you use as much gas in 5 purges at 15 psi (~5 gallons) as it takes to do a 100% liquid prepurge (~5 gallons). At that point the partially filled keg will still contain an unacceptable level of O2, requiring more purges with diminishing returns, while the 100% pre-purged keg is (virtually) O2 free, and gives the benefit of no O2 exposure while filing through the liquid post.

(Semi) closed transfers into 100% pre-purged kegs is remarkably easy to do. With all the time it takes to brew and babysit the beer up to that point, it only makes sense to pay attention to that last step so the last pint tastes as good (or sometimes better) as the first. This is not just for hoppy beers, all beers benefit from that procedure.

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#### applescrap

##### Be the ball!
Thanks Doug for the information. I am still kind of pondering it all. Can enough purges make up for no initial pre purge, that is what I am wondering. I think next time I will try a full liquid purge, rack and pop a bunch of times.

#### The_Bishop

##### Supporting Member
HBT Supporter
If your fermenter is large enough that you don't have any krausen blowoff, you can pipe the CO2 generated right into the liquid post of the keg, then pipe the gas disconnect of that keg into a blowoff tube (or if you have a pressure rated fermenter, a spunding valve).

Five gallons of 1.060 beer at 75% attenuation makes nearly two pounds of CO2. That's a *lot* of purge cycles. I've been doing this for a long while and it's been working well.

#### applescrap

##### Be the ball!
If your fermenter is large enough that you don't have any krausen blowoff, you can pipe the CO2 generated right into the liquid post of the keg, then pipe the gas disconnect of that keg into a blowoff tube (or if you have a pressure rated fermenter, a spunding valve).

Five gallons of 1.060 beer at 75% attenuation makes nearly two pounds of CO2. That's a *lot* of purge cycles. I've been doing this for a long while and it's been working well.
I have heard of this, well and or spunding. Great idea.

#### IslandLizard

##### Progressive Brewing
Staff member
Mod
next time I will try a full liquid purge, rack and pop a bunch of times.
The idea is to leave the lid on the keg after a full liquid pre-purge. Once you open the lid, air will mix into keg, compromising the 100% CO2 space you just created.

#### cswant88

##### Supporting Member
HBT Supporter
If your fermenter is large enough that you don't have any krausen blowoff, you can pipe the CO2 generated right into the liquid post of the keg, then pipe the gas disconnect of that keg into a blowoff tube (or if you have a pressure rated fermenter, a spunding valve).

Five gallons of 1.060 beer at 75% attenuation makes nearly two pounds of CO2. That's a *lot* of purge cycles. I've been doing this for a long while and it's been working well.
This is genius, why have I never heard of it before? The only problem is, I don't have kegs just sitting around waiting for beer. I usually time my brews so I have a keg kick right around the time I'm ready to package. I guess I'll need more kegs

#### Alex4mula

##### Well-Known Member
This is genius, why have I never heard of it before? The only problem is, I don't have kegs just sitting around waiting for beer. I usually time my brews so I have a keg kick right around the time I'm ready to package. I guess I'll need more kegs
Same here. But I think I’ll try it. Great idea. Save some \$\$.

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
This is genius, why have I never heard of it before? The only problem is, I don't have kegs just sitting around waiting for beer. I usually time my brews so I have a keg kick right around the time I'm ready to package. I guess I'll need more kegs
You need more kegs.

Brew on

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
If your fermenter is large enough that you don't have any krausen blowoff, you can pipe the CO2 generated right into the liquid post of the keg, then pipe the gas disconnect of that keg into a blowoff tube (or if you have a pressure rated fermenter, a spunding valve).

Five gallons of 1.060 beer at 75% attenuation makes nearly two pounds of CO2. That's a *lot* of purge cycles. I've been doing this for a long while and it's been working well.
If you feel like getting geeky, I did a detailed analysis of this method of keg purging. It is amazingly effective at reducing O2 content in the keg.

Brew on

#### ian choo

##### New Member
hi guys,

what if the temperature of my beer is 71F how much psi do i need to go for?

I set the keg to 28psi and let it sit for 10 days at room temperature 68-71f (my beer temperature is 66f to 70f) but it came out flat, im using a external kegerator meaning it doest not chill the entier keg it just cold the beer when it pass through a cold chamber and serve at 33-44f so....any idea which part did i go wrong?

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
hi guys,

what if the temperature of my beer is 71F how much psi do i need to go for?

I set the keg to 28psi and let it sit for 10 days at room temperature 68-71f (my beer temperature is 66f to 70f) but it came out flat, im using a external kegerator meaning it doest not chill the entier keg it just cold the beer when it pass through a cold chamber and serve at 33-44f so....any idea which part did i go wrong?
The carb charts don't go up to 71°F, but there are formulas available that will allow you to calculate what is needed. 2.5 volumes of carb requires 31 psi @ 71°F. 28 psi will only give you about 2.33 volumes. Also, with "set and forget" carbonation, you don't get complete carbonation until after about 3 weeks. At 10 days, you're probably somewhere around 2 volumes.

Also, if you didn't properly purge the air out of the keg headspace, your CO2 pressure is less than what the gauge indicates, and you will end up with significantly less carbonation.

Brew on

#### Attachments

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#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
This one does:
Looks like someone added some nice conditional formatting (so it looks like the most common chart shared) and added a beer style table to my spreadsheet.

#### LittleRiver

##### Well-Known Member
Looks like someone added some nice conditional formatting (so it looks like the most common chart shared) and added a beer style table to my spreadsheet.
That's what happens when you do good work. But a credit notation would have been nice....

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
That's what happens when you do good work. But a credit notation would have been nice....
Thanks, but the hard work was done by whoever came up with the formulas in this paper (same paper as linked in my previous post. No author listed, that I can find, but it might be @ajdelange ) My spreadsheet uses equation 2.1 from the linked paper. I have no idea what formula Brewers Friend uses, but it gives slightly different answers than my spreadsheet.

Brew on

#### ian choo

##### New Member
The carb charts don't go up to 71°F, but there are formulas available that will allow you to calculate what is needed. 2.5 volumes of carb requires 31 psi @ 71°F. 28 psi will only give you about 2.33 volumes. Also, with "set and forget" carbonation, you don't get complete carbonation until after about 3 weeks. At 10 days, you're probably somewhere around 2 volumes.

Also, if you didn't properly purge the air out of the keg headspace, your CO2 pressure is less than what the gauge indicates, and you will end up with significantly less carbonation.

Brew on

thanks for the info bro, i will try the burst method now hook it up for 24 hours at 30 psi

i purge 3 times, i set the keg up to 28 psi and release x 3

#### brewbama

##### Well-Known Member
Looks like someone added some nice conditional formatting (so it looks like the most common chart shared) and added a beer style table to my spreadsheet.

View attachment 632882
You do good work. Don’t remember where I got that (on the Internet somewhere) ...but it’s definitely yours. Nice job!

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
thanks for the info bro, i will try the burst method now hook it up for 24 hours at 30 psi

i purge 3 times, i set the keg up to 28 psi and release x 3
3X purge cycles at 28 psi is adequate to insure that you will get the carb level expected. However, if you are brewing very hoppy beers, it is not adequate to prevent premature oxidation of hop flavor and aroma (unless you are doing closed transfer after a liquid purge.)

Brew on

#### applescrap

##### Be the ball!
3X purge cycles at 28 psi is adequate to insure that you will get the carb level expected. However, if you are brewing very hoppy beers, it is not adequate to prevent premature oxidation of hop flavor and aroma (unless you are doing closed transfer after a liquid purge.)

Brew on
I dont understand how those tables work. Can you please help me, I have always wondered. Is that set and forget over u limited time? Thanks again!

#### balrog

##### Supporting Member
HBT Supporter
@applescrap , yes, those charts are set and forget, "static"
Your keg sits at some temp.
You look across the chart to find the volumes CO2 you want
You look to the PSI required
Set that PSI and walk away for 2 weeks.

#### applescrap

##### Be the ball!
Thanks balrog. 2 weeks! That must be why I have never used them. Hope to buy enough kegs someday to have a pipeline like that. Well I guess with one more keg I could do a quick force and let the other 5g of 10g batch slowly carb.

I thought those charts could be used for quicker force, no?

Think I have this right, at a given temp and psi only a certain volume of co2 can be absorbed. Weird, seems like it would just keep pumping it in. Is that newton's law of gases? The science interests me more than the beer. For the beer I just gorilla it and drink warm.

#### balrog

##### Supporting Member
HBT Supporter
It is still a chemical reaction to dissolve CO2 into beer
It does not happen instantly, but is a function of many things like interface surface area, pressure, temperature, concentration already in solution, solubility blah blah blah