5lb co2 gone in 1 keg and carbing 2 more

[Nemanach]

I just started kegging and had a fresh 5lb co2 tank.

I bought a commercial 1/6 barrel keg a month ago and put it in the kegerator.

I brewed a 5g batch and put in a 5g corney. Purged the headspace 6 times, charged to 30 psi for 12 hours. Bled off the pressure and found it not carbonated enough. I turned it back up to 30 psi for 12 more hours. Bled off the pressure and left at 11 psi. This was two weeks ago.

I brewed a 10g batch with my two brothers, each getting 3g after losses. I put the 3g in my 5g keg, purged the head space 6 times. 30 psi for 24 hours, dropped to 11 psi and bled the 30 psi off. This was a week ago.

I brewed a 5g batch and put it in a 5g keg. Purged the headspace 6 times. Put 11 psi in it again and left it out of the kegerator because I didn't have room.

Today I finished the commercial keg. When pouring one off the 5g batch I noticed it was a bit flat and pouring really slow. Gauge still reads 11psi but I think I'm running low on gas because of how slow it is pouring and the lack of carbonation.

I am thinking the 6 times purging the 3g in a 5g keg killed the tank. If that was it then I paid for the education and will move on, if it was something else then I need to figure out what. Do you think that could take down a 5 lb tank that fast or should I be checking for leaks?

 

[Quaker]

If the gauge still reads 11psi, then you shouldn't be pouring slow yet.

Check that you beer out post isn't clogged with something.

Are you using the same line as with the commercial keg or happen to use a longer one for you corny?

Check that the lid is sealed well and no leaks. Considering you had low carbonation on your first stab might indicate you have a leaking seal at a post or kid.

Just a couple of suggestions to look into. Hope it helps

 

[Nemanach]

I'm using the same length line for both.

The beer I keged and carbed a couple weeks ago seemed over carbonated at 12 psi so I turned it down to 11 psi last week. Maybe it is just under carbonated now. Still figuring this all out.

 

[IslandLizard]

Weigh your tank and subtract the tare weight stamped into the neck. That's how many # of CO2 there's left. No it should not be empty after dispensing 1 keg and carbonating 2 others. Even after also purging a half full keg 5x. Unless you have a leak somewhere...

For partially filled kegs, it's best (less oxidation) and way more economical to perform a 100% liquid pre-purge before filling. Fill the keg all the way with Starsan or water and empty out with CO2. You will have then a keg 100% filled with CO2. Then fill the keg through the liquid out post with the PRV open. No air (O2) will get in.

When you do the math, even purging a partially filled keg with 4 gallons of beer, leaving only 1 gallon of headspace, takes more CO2 than a 100% liquid pre-purge as described above, and with a much lower percentage of air (O2) remaining in the headspace.

 

[BrewInspector]

If it reads 11psi then you are not likely out of gas. I think the clog or partial obstruction is likely in that keg. If it was leaking you would probably not be able to maintain a constant psi as the cylinder would be empty by now.

 

[IslandLizard]

Here's a good link to convert an amount of liquid CO2 to gas and vv.

1# of liquid CO2 will produce 8.7 cu ft. of CO2 gas at 14.7 psi (=1 atm, regular atmospheric pressure). 1 cu ft. = 7.5 gallons. A corny keg has a volume of 5.5 gallons.

So 1# of liquid CO2 delivers 8.7 * 7.5 = 65 gallons of CO2 gas. Enough to dispense 65/5.5/(14.7+12)*14.7 = 6.5 kegs at 12 psi on your regulator.

Theoretically a 5# cylinder can thus dispense 5 * 6.5 = 32.5 corny kegs. That's without using gas for anything else like carbonating, purging kegs and headspaces, flushing fermentors, having leaks, etc.

Real life example:
Carbonating a 5 gallon keg of beer to 3 volumes takes 3x its volume in beer, thus 3x5 = 15 gallons of CO2. It takes 5.5*(14.7+12)/14.7 = 10 gallons to dispense. Add another 5.5+4.5 = 10 gallons for purging, bleeding, and stuff for a total of 15+10+10 = 35 gallons of CO2, or 35/65 = about 0.5# of liquid CO2.

A 5# tank can thus purge, carbonate and serve around 9-10 corny kegs of beer that way.

 

[Nemanach]

Thanks for the tips everyone. I'll start doing liquid purged before filling to save on gas. Weighing the tank is a good idea, I'll see where that is at and so if I can figure out if something is plugging up the keg. I dry hopped in a bag but it certainly could have came open.

 

[IslandLizard]

Thanks for the tips everyone. I'll start doing liquid purged before filling to save on gas. Weighing the tank is a good idea, I'll see where that is at and so if I can figure out if something is plugging up the keg. I dry hopped in a bag but it certainly could have came open.

Let us know how much CO2 is left. Just curious.
Also make a note of the weight of the tank with regulator and typical hoses attached, so you can easily reweigh at later time, without removing the regulator.

Hop fibers can get stuck in the liquid out post, around the poppet. In bad cases they can plug the diptube too.

A 100% liquid pre-purge is the best way to limit O2 exposure in the receiving vessel (keg). It does cost an extra 9-10 gallons of CO2 at 8-10 psi to do that, regardless of fill level. Although technically not needed, perhaps a few extra headspace purges after filling, for all security.

A fully closed transfer system is ideal, but not always feasible on homebrew scale. There are plenty of threads and articles on how to accomplish limited or low O2 and even complete O2-free transfers.

 

[doug293cz]

Do you have one or two gauges on your regulator? If two, the high pressure gauge doesn't tell you anything until you are almost out of CO2 (physics of compressed gas over liquid.) If the CO2 tank is in your kegerator/keezer, then the high pressure gauge will read in the red zone, even with a full tank. But if it drops close to zero, then you may be out of gas. However, as stated by someone else, if you still have 11 psi on the low pressure gauge, you are not totally out of CO2.

If you pressurize at 11 psi at a temperature above your serving temp, you will not get the carbonation level you are looking for. At room temp, 11 psi will only give you about 1.4 volumes of carb.

Finally, as long as you are holding the pressure set by your regulator, your beer will carb to the value determined by the pressure adn temperature. The chart here shows the equilibrium carb level as a function of temp and pressure. It can take up to two to three weeks for the carbonation to reach equilibrium. If you have a slow leak, you will still carbonate (since that only depends on having the correct pressure) but you will run out of CO2 much faster.

Brew on

 

[Quaker]

I dry hopped in a bag but it certainly could have came open.

My money's on hop matter clogging you up somewhere between the dip tube, post, or disconnect.

 

[madscientist451]

Thanks, Island Lizard, for the explanation of how to determine Co2 consumption.
I have plenty of kegs, and sometimes if my beer pipeline is full, I'll prime a keg with sugar, put just enough gas on to make it seal and purge the air out, and let it sit a couple of weeks.
I figured I was saving some Co2 by doing this, but never really figured out how much. By your calculations above it looks like I'm saving about .23 lb. of Co2 for each keg that is primed. So putting aside the difference between "keg conditioned" and force carbonated, I'm thinking the practice of adding priming sugar isn't really worth doing.

 

[oylerck]

Thanks for the tips everyone. I'll start doing liquid purged before filling to save on gas. Weighing the tank is a good idea, I'll see where that is at and so if I can figure out if something is plugging up the keg. I dry hopped in a bag but it certainly could have came open.

Release the pressure completely and switch your valve connectors so that the co2 hose is connected to the liquid out connector. You must switch the connectors or you risk ruining the o-ring or worse. Blow some co2 into the liquid out and see if you can clear the hop matter.

Releasing the pressure is important because you do not want liquid up your gas line.

This should help clear it, but if it happens again you may have to put a screen on the dip tube by taking the liquid ball valve and poppet assembly apart.

 

[Nemanach]

Release the pressure completely and switch your valve connectors so that the co2 hose is connected to the liquid out connector. You must switch the connectors or you risk ruining the o-ring or worse. Blow some co2 into the liquid out and see if you can clear the hop matter.

Releasing the pressure is important because you do not want liquid up your gas line.

This should help clear it, but if it happens again you may have to put a screen on the dip tube by taking the liquid ball valve and poppet assembly apart.

I have put the gas disconnect on the liquid our disconnect before and didn't have any immediate problems. What could happen if you have the gas on he liquid line aside from possibly filling the liquid line with beer if the keg has higher pressure.

Full sanitizer purge advocates such as IslandLizard, how do you dry hop in keg if you do a full liquid purge like you described?

 

[IslandLizard]

Full sanitizer purge advocates such as IslandLizard, how do you dry hop in keg if you do a full liquid purge like you described?

I expected that question for a long time, but you're the first to ask.

I used to dry hop in the primary fermentor (bucket), but I prefer keg hopping. So yes, there's a dilemma to keep O2 out.

100% liquid pre-purged keg is filled through the liquid out post. No air gets in that way. All good. I haven't practiced a closed transfer with a bucket, but it's possible.

Dry hopping in keg:
I fill and prep the dry hop bag, suspension wire, and "suspension lid" if I have one spare. Otherwise it's dental floss or just the bag without suspension. I weigh the bag down by adding a handful of (sanitized) glass marbles.

For the following maneuver, work fast and smoothly to keep the gas "blanket" in the keg's headspace as much undisturbed as possible.
I stream CO2 through the gas-in post at a good rate, around 12 psi with the PRV open. Release and remove the lid, slowly lower the dry hop bag then mount the suspension lid. Or wrap the floss around the gas QD and mount the old lid. Purge 5-7x at 30 psi. I roll the keg for a few minutes, then purge again.

If anyone has a better method, I'm all ears.

 

[brewbama]

To dry hop in a keg you could use a hop bag or something

 

[oylerck]

I have put the gas disconnect on the liquid our disconnect before and didn't have any immediate problems. What could happen if you have the gas on he liquid line aside from possibly filling the liquid line with beer if the keg has higher pressure.



Full sanitizer purge advocates such as IslandLizard, how do you dry hop in keg if you do a full liquid purge like you described?

You can ruin the regulator with liquid. That's the main thing. If the pressure in the keg is more than the co2 pressure it can back up. Just an expensive mistake if it happens.

 

[MagicMatt]

FWIW, when I purge my kegs after filling I do it 15 times @ 20psi. I then set the regulator to 40psi and stick it in my keezer @ 34°F for 24 hours, then purge and keep it at 9psi for another few days until fully carbed.

I do this to every keg, and a 5lb CO2 tank lasts me at least 10 kegs. That's with serving these kegs as well.

So I don't think your little 6 purges are doing this to you.

 

[Nemanach]

When I put the tank on my scale by itself it said I had .7 lbs after subtracting the tare weight. I weighed it with me holding it and got 3.5 lbs left. The 3.5 lbs is probably more accurate. I messed with the keg post,, turned pressure up and down and everything seems fine now.