Pressure dilemma !

[roosmur]

I have moved from bottling to kegging my beer, and have a corny keg and a Co2 cylinder with regulator. I have used calculators online to determine the correct pressure setting for carbonation, depending on beer style, and, after determining the temperature the carbonation will happen at, I set this pressure and leave my keg connected for a few days. ie I am happy with step one, which is carbonating my beer. Dispensing it from the keg is a different story...

I shut off my gas supply, vent my corny keg (lots of gas escapes with a big hiss) but then when I tap out beer I get an almighty gush and a big glass of foam. For some reason, even if the headspace pressure is elininated by venting, I get flow out of my keg which is way too fast.

Given the Co2 from carbonation should be in the beer itself, this shouldn't happen. Do I need longer lines from my keg to my tap (or thicker ones)? But then I would have to change these for each carbonation style if I wanted the same dispensing pressure.

Is it the nozzle on my tap that diffuses the beer perhaps, and makes it too foamy?

Any ideas most welcome.

 

[rajun50]

What temperature is your beer and what pressure are you set at? How long are your lines? Are you opening the tap all the way when you pour, or just partially?

It is very strange that your beer is pouring fast even after venting all the pressure in the keg. If I vent all the pressure from one of my kegs I get nothing at all coming out of the tap (which is the expected outcome, obviously). For your beer to pour fast after venting all pressure, CO2 would have to be coming out of solution at a pretty high rate to re-pressurize the headspace. That would be a pretty odd thing to happen, especially if your beer is cold.

 

[roosmur]

Yeah, especially since the keg tap is on the top of the keg. I have not tried this at cold temperatures though, mind you. It has always been fairly warm. Perhaps I should drop the temperature and remove the diffuser nozzle altogether, and try again.

 

[Yooper]

Yeah, especially since the keg tap is on the top of the keg. I have not tried this at cold temperatures though, mind you. It has always been fairly warm. Perhaps I should drop the temperature and remove the diffuser nozzle altogether, and try again.

Warm beer foams. That's just what happens when pouring warm beer. Colder beer "holds" onto the c02 better.

Longer lines would probably help a lot by providing more resistance. You really can't go too long, so you could pour at any pressure if you have enough restriction. As an example, I had a soda set up in my basement at about 40 psi. With 30' of line, it poured pretty well.

 

[roosmur]

My keg fits into my fridge, but not my C02 bottle and regulator, and I don't want to damage my fridge magnetic lining in order to allow the gas line to go in. ie I need to carbonate my beer first, outside the fridge, then transfer it to the fridge once carbonated to chill to serving temperature.

When I look at the calculators, they ask for the carbonation level needed (ie 2.0 volumes CO2) and for the temperature of carbonation, in order to determine the psi setting on the gas bottle regulator.

If I carbonate to 2.0 volumes CO2 at 70-75 degrees (ie my keg is in the cellar) then disconnect my gas bottle after a few days (once I am sure we have the right pressure in there) and put my keg in the fridge and chill down to 40 degrees, then vent my keg at serving time, will the actual carbonation of my beer still be 2.0 volumes? Or do I need to carbonate it plugging in the expected serving temprature, even if this is not the temperature I carbonate at?

Would love someone to point me in the right direction!

 

[rajun50]

I imagine it will take longer to carbonate at warmer temperatures if you just go by the chart and slow-carb. I haven't personally tried this warm, so I could be wrong, but I know CO2 is less soluble at warmer temps. When I carb in my kegerator, it takes around a week to get close to the correct amount of carbonation, albeit not spot-on. Two weeks (ish) is the general time recommended for slow-carb at cold temps. I guess what I'm trying to say is that a few days will not be enough to fully carbonate your beer if you are doing it by the "set and forget" method, especially at warm temperatures.

That being said, whatever level of carbonation you are at will hold no matter what the temperature changes to (in a closed vessel, of course). So, if you carbonate your beer to the proper level warm, then chill it, it will still be at the proper level of carbonation. You also shouldn't have to vent your keg at serving time for a beer that is carbonated at 2 volumes. Your cold carbonating pressure and serving pressure will be the same once the beer is chilled.

I hope my explanation is clear enough, but for clarity's sake I'll explain some more. (hypothetical carb psi numbers right now, as I don't have my carb chart handy) A beer carbed warm to 2 volumes at 30psi will be at the same carbonation level as a 40 degree beer carbed at 8psi. Those two are not interchangeable, though. What I mean is that you can't carb a warm beer to 2 volumes at 8psi, disconnect, and then chill it and expect it to be carbonated the same as a 40 degree beer carbonated cold at 8psi. A warm beer will never get close to 2 volumes at 8psi, as warm beer requires more pressure to carbonate, due to lower solubility of CO2 at the higher temperature.

One more thing to note: If you disconnect your gas and serve with the beer's carbonation only, you will slowly be losing carbonation the whole time. This will lead to slow pours and a beer that is eventually carbed at less than 2 volumes. You really need to have your gas connected while serving if you want to keep everything exactly right.

I hope all that is helpful and understandable. If you have any other questions feel free to ask. I also hope all my info (aside from the hypothetical ballpark numbers) is correct, so someone please correct me if I'm wrong. I've had a beer or 7 today.

 

[roosmur]

Thanks very much. Clear. My issue in testing has been I have warm carbed to the right volume (as you say, hi psi needed) then tried to dispense warm and had beer fly out of the keg too fast. Now understand why.

Will carb to 2 vols warm, chill to right temp, then dispense. When the evening or party is over I can reconnect to gas and recarb keg if i don't finish it all I guess...



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