Corny keg not carbonating at 25psi?

[Jayhem]

I've been researching this and only thing I can think of is that I either have a problem with my regulator or CO2 tank.

I have a 5 gallon corny keg on the gas right now at 25psi at 35*F. It's been on the gas for a week. I check for gas leaks using dish soap in a spray bottle as always, no leaks. When I pull the gas relief valve on the keg I get a strong flush of CO2, definitely sounds like 25psi to me.

But still after 7-10 days at 25 psi the beer is undercarbonated and has a head on it for only 30 seconds after a pour and then only a few bubbles can be seen in the glass if I shake the glass lightly.

I don't get it. My tank is probably nearly empty as this is the 4th batch I've force carbonated and served on one 5 lb cylinder but the gauge still reads 900 psi on the tank.

 

[phyllobeddo]

With only four batches under your belt and the tank almost empty, I would think you had a slow leak. I've carbonated about 20 2.5 gallon batches over the past year and a few months and I still have CO2 in my 5 lb tank. Granted, it's almost out, but still, I'm sure you get the point.

 

[Jayhem]

With only four batches under your belt and the tank almost empty, I would think you had a slow leak. I've carbonated about 20 2.5 gallon batches over the past year and a few months and I still have CO2 in my 5 lb tank. Granted, it's almost out, but still, I'm sure you get the point.

I have no idea if my tank is almost empty, I've just heard that you don't usually get more than 4-5 five-gallon batches force carbed and served on one tank. The gauge on the tank stays the same until it's empty so unless I weighed the tank before filling and after I would have no way to track how much CO2 is left. I've checked all connections with soap water before assembling each keg. I'm fairly confident I have never had a leak but if I did have a slow leak but there is still plenty of CO2 pressure on my keg it should still be carbonating...that's what makes no sense.

 

[doug293cz]

I've been researching this and only thing I can think of is that I either have a problem with my regulator or CO2 tank.

I have a 5 gallon corny keg on the gas right now at 25psi at 35*F. It's been on the gas for a week. I check for gas leaks using dish soap in a spray bottle as always, no leaks. When I pull the gas relief valve on the keg I get a strong flush of CO2, definitely sounds like 25psi to me.

But still after 7-10 days at 25 psi the beer is undercarbonated and has a head on it for only 30 seconds after a pour and then only a few bubbles can be seen in the glass if I shake the glass lightly.

I don't get it. My tank is probably nearly empty as this is the 4th batch I've force carbonated and served on one 5 lb cylinder but the gauge still reads 900 psi on the tank.

How are you serving the beer, picnic tap or regular tap? How long is your beer line? Is the beer line and tap cold? Are you getting foamy pours, that are then flat when the foam subsides? Beer lines that are too short or too warm are common problems with keg systems.

Did you purge and refill the headspace multiple times after sealing the keg? If not your effective CO2 pressure (more correctly the CO2 partial pressure) may be less than you think, and you will not carb as fast or as well as intended.

At a constant temperature, the high pressure gauge will not change until all of the liquid CO2 in the tank is gone. Then the pressure will drop rapidly as you use up the remaining CO2 gas in the tank, A room temp CO2 tank with any amount of liquid CO2 in it (from 5 lbs down to 0.01 lbs) will read 800 to 900 psi, depending on temp. A CO2 tank in the fridge containing any liquid will read between 500 and 600 psi, depending on fridge temp.

Brew on

 

[Jayhem]

See my responses in RED

How are you serving the beer, picnic tap or regular tap? How long is your beer line? Is the beer line and tap cold? Are you getting foamy pours, that are then flat when the foam subsides? Beer lines that are too short or too warm are common problems with keg systems. Perlick faucet on kegerator, My liquid line was balanced correctly for serving at 10psi. It's about 5-6' of 1/4" ID with the faucet 24" above the keg ball locks, I get about 2" of foam when I pour but it subsides within 30 seconds and then the beer is pretty flat, the beer line and the perlick faucet stay cold in the refrigerated tower I serve from on my kegerator.

Did you purge and refill the headspace multiple times after sealing the keg? If not your effective CO2 pressure (more correctly the CO2 partial pressure) may be less than you think, and you will not carb as fast or as well as intended.
I purge after filling the keg with beer at 20 psi, 3 second bursts about 4-5 times. I've carbed 3 other kegs with the same method and had no problems on the first 3 kegs on this tank

At a constant temperature, the high pressure gauge will not change until all of the liquid CO2 in the tank is gone. Then the pressure will drop rapidly as you use up the remaining CO2 gas in the tank, A room temp CO2 tank with any amount of liquid CO2 in it (from 5 lbs down to 0.01 lbs) will read 800 to 900 psi, depending on temp. A CO2 tank in the fridge containing any liquid will read between 500 and 600 psi, depending on fridge temp. That makes sense, my tank is at 75F and reads 900 PSI and has since it was first filled.

Brew on

 

[doug293cz]

See my responses in RED

1/4" ID beer line should almost never be used in a home system. It takes almost 4 times as long a line to get the proper pressure drop vs. a 3/16" ID line. Your line is definitely not "balanced correctly" for serving at 10 psi. Check out the beer line calculator here. The author also explains the science behind proper beer line length and diameter if you care to read about that.

Brew on

 

[Jayhem]

1/4" ID beer line should almost never be used in a home system. It takes almost 4 times as long a line to get the proper pressure drop vs. a 3/16" ID line. Your line is definitely not "balanced correctly" for serving at 10 psi. Check out the beer line calculator here. The author also explains the science behind proper beer line length and diameter if you care to read about that.

Brew on

Oops. Sorry I just double checked. I have 1/4" gas line and 3/16" beer line at 6' long and 2' of lift to the faucet. According to that calculator that is about an 8.5 second/pint flow rate.

 

[Iseneye]

You're carbing at 35 degrees and 25PSI? That's going to give you 4 volumes C02 when it should be around the 2.5 mark.

 

[raouliii]

See my responses in RED ........ I get about 2" of foam when I pour but it subsides within 30 seconds and then the beer is pretty flat.........3/16" beer line at 6' long and 2' of lift to the faucet. According to that calculator that is about an 8.5 second/pint flow rate.

IMO, that 2" head is where most of the carbonation is going. The calculator indicates a, very fast, 5 sec/pint flow rate with your numbers. Longer beer line and lower carb/serving pressure is my recommendation. 10 feet and 12psi will double that sec/pint rate to a more appropriate value of about 10. Of course, if you REALLY want 25psi on that keg, it'll take about 21 feet of beer line to tame it.

 

[Jayhem]

UPDATE: So I disconnected my gas line from the keg, cleaned and reconnected and put it back on gas for 24 hours and now I have carbonated beer and I backed it down to 8psi for serving and it's pouring a nice pint with 1" of head that lingers and nice full carbonation! Not sure what the problem was but my beer was not getting gas for that first week. Maybe my poppet or ball lock was the problem and cleaning it seemed to remedy the problem!

Thanks for the replies, carry on!

 

[barnaclebob]

How full was the keg? The co2 absorption rate is dependent on the contact area between the CO2 and the beer. The first keg I filled by transferring it in through the dip tube I filled all the way to the pressure release valve and it was taking forever to finish carbonating after a little force carbing using the shaking method until I had poured about a pint out through sampling.

 

[doug293cz]

How full was the keg? The co2 absorption rate is dependent on the contact area between the CO2 and the beer. The first keg I filled by transferring it in through the dip tube I filled all the way to the pressure release valve and it was taking forever to finish carbonating after a little force carbing using the shaking method until I had poured about a pint out through sampling.

Yeah, if you fill above the straight wall level of the keg, you will slow the carb rate down. The rate at which CO2 enters the liquid is proportional to the difference between the current carb level and the equilibrium level (for the temp and CO2 pressure.) times the surface area. So, the carbonation rate drops as the carbonation level increases. The CO2 entry rate is measured in units of mass/(time · area), but the carbonation rate is in units of (mass · height)/(time · area), so the greater the height of the beer "column" in the keg the longer it takes to carb. If the keg is 1/2 full, it will carb twice as fast. Headspace volume doesn't matter.

Brew on