Kegging question regarding O2/co2, regulator PSI

[jnlipas]

Hello,

Yesterday I kegged my first batch of beer (I know, I got ambitious and went straight to kegging instead of bottling) and I did not pull on the relief valve after I filled the keg with beer. Once I started filling the keg with co2 I did pull on the relief valve some and I didn't have any beer shoot up but I could hear the keg filling with co2. I am worried that there is still O2 in the keg and that I've ruined my beer .

My other question is that I am confused as to what PSI I should be carbonating my beer at. I don't have a kegerator or other means of keeping the keg cool, so my plan was to just let it carbonated for a week or so before filling a growler and chilling it. A coworker of mine said to leave the regulator at 12 PSI and the tank turned on with the shutoff valve open so there is co2 constantly flowing in to it. I've also read other forums/watched videos where people are carbonating it and then disconnecting it. Currently I have the regulator set to 20 PSI and and have the tank open/shutoff valve open. Is there a surefire way to carbonate the way I am trying to (outside of a kegerator in about a 65 - 70 degree basement)? I'm just really nervous about screwing up my first batch.

Thanks for your time.

 

[GilSwillBasementBrews]

You want to leave the gas on and shutoff open. Here is a chart for volume of co2 per Psi and temp. You will need a higher PSI setting at room temp than you would if leg was cold. View attachment ImageUploadedByHome Brew1436836424.924912.jpg

 

[Iseneye]

Hello,
Yesterday I kegged my first batch of beer (I know, I got ambitious and went straight to kegging instead of bottling) and I did not pull on the relief valve after I filled the keg with beer. Once I started filling the keg with co2 I did pull on the relief valve some and I didn't have any beer shoot up but I could hear the keg filling with co2. I am worried that there is still O2 in the keg and that I've ruined my beer .

I think I read the same question a week or so ago from a different poster

There will likely still be 02 in the keg so purge the keg about 5 times and you should be alright - i.e. release valve until vented, wait for it to refill, x5). Beer is tough and should still taste fine. Bottling will introduce just as much, if not more O2 than what you have done.

 

[jnlipas]

I think I read the same question a week or so ago from a different poster

There will likely still be 02 in the keg so purge the keg about 5 times and you should be alright - i.e. release valve until vented, wait for it to refill, x5). Beer is tough and should still taste fine. Bottling will introduce just as much, if not more O2 than what you have done.

Definitely seems to be a common question among us noobs :cross:. When you say "release valve until vented" does that mean release it until nothing is coming out when you pull up on the valve? I lifted up on it for a while earlier and it went for a while then got audibly quieter but it still sounded like just a little something was coming out.

 

[IslandLizard]

After filling your keg, closing the lid, you need to purge the air (O2) out. The best would be to vacuum, then fill with CO2. Near 100% replacement in one shot.

But most of us don't have a vacuum pump, so we need to resort to the next best thing, which isn't perfect but workable. Set regulator to 30 PSI, let fill, pull the relieve valve. Repeat 5 times. Lower psi settings require more purges, higher psi settings fewer. Law of diminishing returns.

You can do the math on how much O2 is left in the headspace after that (O2 makes up 21% of air). BTW, assume the CO2 and air mixes completely in that process, as it does.

The smaller the headspace, the less air is left with each cycle. That's why you'd waste more gas the larger the headspace, say to purge a keg filled only half way, and 5 purges may not be sufficient...

There are a lots of posts (Google) and YouTube vids on this technique.

 

[IslandLizard]

Look up force carbonating. Particularly by rolling the keg for 5-10 minutes.

If you haven't shaken the keg yet, you can still purge that air out a few more times. But if your keg was full (4.5-5 gallons), there is not much air in there anyway, relax.

 

[doug293cz]

Hello,

Yesterday I kegged my first batch of beer (I know, I got ambitious and went straight to kegging instead of bottling) and I did not pull on the relief valve after I filled the keg with beer. Once I started filling the keg with co2 I did pull on the relief valve some and I didn't have any beer shoot up but I could hear the keg filling with co2. I am worried that there is still O2 in the keg and that I've ruined my beer .

My other question is that I am confused as to what PSI I should be carbonating my beer at. I don't have a kegerator or other means of keeping the keg cool, so my plan was to just let it carbonated for a week or so before filling a growler and chilling it. A coworker of mine said to leave the regulator at 12 PSI and the tank turned on with the shutoff valve open so there is co2 constantly flowing in to it. I've also read other forums/watched videos where people are carbonating it and then disconnecting it. Currently I have the regulator set to 20 PSI and and have the tank open/shutoff valve open. Is there a surefire way to carbonate the way I am trying to (outside of a kegerator in about a 65 - 70 degree basement)? I'm just really nervous about screwing up my first batch.

Thanks for your time.

You can carbonate at room temperature, but dispensing at room temp into a growler will be an issue. Since you will need to carbonate at around 30 psi at room temp, you would need about 30 ft of 3/16 ID tubing to dispense without horrendous amounts of foam. Also, carbonation is not very stable at room temp, so you are likely to end up with flat beer in the growler, even if you do have long dispense lines.

Brew on

 

[Iseneye]

But most of us don't have a vacuum pump, so we need to resort to the next best thing.

Sorry to pick out one point from your excellent post. If you have the capability of CO2 transfer (such as keg fermenting) you can fill the receiving keg with water and then remove with C02. This leaves nearly 100% CO2 in the receiving vessel.

 

[IslandLizard]

Sorry to pick out one point from your excellent post. If you have the capability of CO2 transfer (such as keg fermenting) you can fill the receiving keg with water and then remove with C02. This leaves nearly 100% CO2 in the receiving vessel.

No need to say sorry, you've provided an excellent way to replace all air with CO2, but you do use 5.5 gallons of CO2 gas in the process. Instead of water you really should fill the keg with Starsan, to sanitize it in the same step. And make sure to blow all of it out!

The bigger issue is how to fill that keg with beer, without adding air to it that you've so carefully eliminated. You can't remove the lid. So ideally it should be filled through the liquid side (via the QD) with the PRV open. If there is no manual PRV, stick an open QD on the gas post to vent.

Use either an auto siphon or put an ever so slight pressure on the containing vessel (usually fermentor) to get the siphon started, without blowing up the vessel. In some cases it's best to flush the racking cane and tubing with CO2, before moving the beer.

 

[peterj]

Here's a good post that will help you understand about keg carbonating: https://www.homebrewtalk.com/showthread.php?t=73328. It's a sticky on this forum.

The chart in the second post will help you find the right PSI. If your keg was cold then your coworker would be right about 12 psi, but since it's at room temp it should be somewhere around 30 psi probably. Here's a calculator that basically tells you the same thing as that chart: http://www.brewersfriend.com/keg-carbonation-calculator/.

It will likely take longer than a week to carb up if you set it and forget it at 30 psi at room temp. Though I've never carbed anything at room temp before so I'm not positive.

And as someone else said, you probably will have a rough time trying to fill a growler with carbonated room temp beer. Even if you turn the pressure way down I still don't think it will work well.

Also, when I purge the headspace I hook up the gas at 30 psi to fill it, then disconnect the gas every time I purge it so you know when it's fully purged.

 

[doug293cz]

...

Also, when I purge the headspace I hook up the gas at 30 psi to fill it, then disconnect the gas every time I purge it so you know when it's fully purged.

If you have a valve between the regulator and the keg, you can just close that valve with purging. Otherwise pull the gas QD off the keg before purging.

Brew on

 

[peterj]

If you have a valve between the regulator and the keg, you can just close that valve with purging. Otherwise pull the gas QD off the keg before purging.

Brew on

Yeah I usually pull the QD instead of closing the valve. I think I started doing it that way so I wouldn't waste the small amount of CO2 in the gas tubing (not that it would make much difference). Works either way though!

 

[Iseneye]

No need to say sorry, you've provided an excellent way to replace all air with CO2, but you do use 5.5 gallons of CO2 gas in the process. Instead of water you really should fill the keg with Starsan, to sanitize it in the same step. And make sure to blow all of it out!

The bigger issue is how to fill that keg with beer, without adding air to it that you've so carefully eliminated. You can't remove the lid. So ideally it should be filled through the liquid side (via the QD) with the PRV open. If there is no manual PRV, stick an open QD on the gas post to vent.

I meant Starsan but said water. I know that I am using a chunk of C02 pushing the starsan water out. I fill my keg from liquid out to liquid out with quick disconnects so there should be little 02 transfer. Would you suggest that I don't need to purge the receiving keg using the water transfer method? It would save me some time - not too worried about the C02 cost.

 

[IslandLizard]

Not sure I understand. Are you saying you're moving beer from one keg to another (liquid out to liquid out)? Why do that?

Most people will just rack from fermentor into the keg through the lid opening. The racking hose goes to the bottom of the keg to prevent splashing. Then close up and purge. The amount of air exposure is small, but for some beer (e.g., highly hopped IPAs, beer that needs to age a long time) the less air the better. Then a prepurged keg is the best method. For many beers you may never notice the difference, as long as the air exposure isn't excessive, like bubbling air through the hoses and the beer in the keg.

 

[pshankstar]

Definitely seems to be a common question among us noobs :cross:. When you say "release valve until vented" does that mean release it until nothing is coming out when you pull up on the valve? I lifted up on it for a while earlier and it went for a while then got audibly quieter but it still sounded like just a little something was coming out.

I'm wondering the same thing & continue to look on this forum. I will go through the long sticky on kegging to see if I can find the answer there. I think we would want to vent it all out this way the CO2 forces the lighter O2 out of the keg but I could be wrong. I will be doing my first force carbonating late next week. So I'm slowing looking through the forums to get confirmation on my assumption to vent till there is no more noise. Thanks everyone for such a great community!!! [emoji106]

 

[peterj]

I'm wondering the same thing & continue to look on this forum. I will go through the long sticky on kegging to see if I can find the answer there. I think we would want to vent it all out this way the CO2 forces the lighter O2 out of the keg but I could be wrong. I will be doing my first force carbonating late next week. So I'm slowing looking through the forums to get confirmation on my assumption to vent till there is no more noise. Thanks everyone for such a great community!!! [emoji106]

Correct, as long as the gas QD is disconnected or the valve is shut you should vent until nothing more comes out.

Also, the CO2 doesn't force the "lighter" O2 out. Gasses don't settle out like that. Especially when you're forcing CO2 in at pressure, you can assume they pretty much mix evenly. That's why you vent and repressurize a number of times to get the mixture to be mostly CO2.

 

[doug293cz]

Correct, as long as the gas QD is disconnected or the valve is shut you should vent until nothing more comes out.

Also, the CO2 doesn't force the "lighter" O2 out. Gasses don't settle out like that. Especially when you're forcing CO2 in at pressure, you can assume they pretty much mix evenly. That's why you vent and repressurize a number of times to get the mixture to be mostly CO2.

Exactly right!

You can easily calculate the percent of original headspace O2 remaining based on the number of purges and the regulator pressure used for purging:

Percent of original O2 remaining = 100% * (14.7 / (14.7 + Gauge_Pressure))^n
where n = the number of purge cycles​

The above assumes you vent the headspace completely at each purge cycle.

Edit: Corrected formula (not enough coffee yet.) Also, if you are at significant altitude, replace 14.7 by your local atmospheric pressure (in psi.)

Brew on

 

[AnOldUR]

You can easily calculate the percent of original headspace O2 remaining based on the number of purges . . .

Have you graphed this? Must be an exponential curve with diminishing return. What is the optimum number of purges? Where "close" is good enough and you're just wasting CO2.

 

[robbyice]

on the temperature on psi chart.. where does time come into play?

a few hours at the appropriate psi for the temp wont correctly carb a beer... where is the time?

 

[peterj]

Exactly right!

You can easily calculate the percent of original headspace O2 remaining based on the number of purges and the regulator pressure used for purging:

Percent of original O2 remaining = 100% * (14.7 / Gauge_Pressure)^n
where n = the number of purge cycles​

The above assumes you vent the headspace completely at each purge cycle.

Brew on

Nice! I did these estimates roughly but never came up with an actual formula. Though I would correct it to this:

Percent of original air remaining = 100 * (14.7 / (Gauge_Pressure + 14.7))^n

because you have to account for the 1 atmosphere that will be in the keg to begin with (and whenever you fully vent the pressure).

When I did it I just figured that adding 30 psi of CO2 would add ~2 atm (I rounded 14.7 psi to 15) worth of gas to the 1 atm of air that was already in there and thus would reduce the total concentration of air by 1/3. So if you purge 4 times you have (1/3) * (1/3) * (1/3) * (1/3) = (1/81) = 1.23% of air in there. If you purge again you have ~0.4%. I would say that's about where the diminishing returns come in. I think 4 or 5 times is plenty.

 

[peterj]

on the temperature on psi chart.. where does time come into play?

a few hours at the appropriate psi for the temp wont correctly carb a beer... where is the time?

The time is going to be about 2 - 3 weeks unless you are shaking it in or something. The chart will tell you what the ending equilibrium volumes of CO2 will be. It doesn't really take time into account other than that it assumes you give it enough time to come to equilibrium.

 

[AnOldUR]

Given a temperature and pressure, the biggest factor in time is surface area. Regardless of the amount of head space, the surface area in a keg is the same, so that won't change it.

Suppose you could lay your keg on its side.

 

[doug293cz]

Have you graphed this? Must be an exponential curve with diminishing return. What is the optimum number of purges? Where "close" is good enough and you're just wasting CO2.

Here you go:





Brew on

 

[AnOldUR]

Here you go:

Nice! For no particular reason, I've always done 4 or 5 purges @ 30PSI. By pure luck, that looks like where the curve starts to flatten out. Thanks.

 

[doug293cz]

Nice! I did these estimates roughly but never came up with an actual formula. Though I would correct it to this:

Percent of original air remaining = 100 * (14.7 / (Gauge_Pressure + 14.7))^n

because you have to account for the 1 atmosphere that will be in the keg to begin with (and whenever you fully vent the pressure).

When I did it I just figured that adding 30 psi of CO2 would add ~2 atm (I rounded 14.7 psi to 15) worth of gas to the 1 atm of air that was already in there and thus would reduce the total concentration of air by 1/3. So if you purge 4 times you have (1/3) * (1/3) * (1/3) * (1/3) = (1/81) = 1.23% of air in there. If you purge again you have ~0.4%. I would say that's about where the diminishing returns come in. I think 4 or 5 times is plenty.

Yeah, I got sloppy, but have corrected it. The formula applies equally to percentage of original O2 or original air, since it is based on ratios. If I remove 1/2 of the original air, I also remove 1/2 of the original O2.

Brew on

 

[peterj]

Yeah, I got sloppy, but have corrected it. The formula applies equally to percentage of original O2 or original air, since it is based on ratios. If I remove 1/2 of the original air, I also remove 1/2 of the original O2.

Brew on

Oh right, that's true!

Also, nice graph!

 

[pshankstar]

Awesome guys and thank you for all of the valuable information!!! This forum has been such a great wealth of information and everyone is so willing to help each other out!! I hope I will be in that position in the near future!! [emoji106]