First time kegger question

Discussion in 'Home Bar' started by Liberatiscioli, Apr 13, 2017.

  1. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    First time kegging. Practiced a bit with water. Tested lines for leaks, took temp readings from beers in my fridge. Made calculations to balance my system.

    Going to go with the slow method for carbonating. Set it and forget and wait for a NEIPA.

    My question is how long should I wait to bleed any headspace oxygen out of the keg. Only want to try and do it once. Keeping the carb low about 2.2 vol CO2.

    Cheers and thanks in advance!
  2. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    You need to purge the headspace immediately after you keg. Pressurize, burp, pressurize, burp, etc, until all you have left is CO2. Technically, that's not possible, but you want to get it as low as you can. Every time you pressurize, the CO2 mixes with the air that's in the headspace, then the burp lets out that mixture so you're left with a blend of CO2 and air.

    Grossly oversimplified, if you add 2 vols of CO2 to the 1 vol of O2 laden 'air' that's in the headspace, you end up with a mixture that is 66% CO2, 33% air (excuse the rounding - this is just an illustration). After you burp, you have 1 vol of that mixture left. Add 2 vols of CO2 to that, the mixture becomes 88% CO2, 12% air. Do it again and you've got 96%/4%. The more times you burp, the more O2 is purged from the headspace, but the law of diminishing returns applies here. And you'll never actually get to zero using this technique. How much is enough? That's up to you. I'm usually content with 4 or 5 or 6 or 7 or...
    NeroFiddled likes this.
  3. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    Ok so fill the keg. Instead of turning to 8 on the regulator turn to 2 and burp? Rest 5 min burp, repeat x 5?
    Then turn the regulator to 8 and rest for a week or so?
  4. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    I guess I'm unsure of the proper pressure to be applied and intervals of burping.
  5. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    You can apply as much pressure as you like. The higher the pressure, the more dilution in each iteration, so the fewer repeats to achieve the same result.

    I'm not a fluid dynamics guy, so I'm making a lot of generalizations here. My vocabulary in that subject is also lacking. The concept is sound, though, so bear with me. Somebody who knows more about this will, hopefully, jump in to clarify and correct me where I'm wrong.

    At 11 psi, and around 38 F (typical numbers for chilled beer) you can squeeze about 2.5 volumes of CO2 into a given volume, relative to ambient pressure. I use 11 psi simply because that's where my regulators are typically set. Pressurize, burp, pressurize, burp, ..., until you're done. That's it.
    Liberatiscioli likes this.
  6. PortLargo

    PortLargo Devotee (466) Oct 19, 2012 Florida

    You hit it all correctly.

    At sea level on earth, what most people call zero pressure is actually 14.7 psi (absolute pressure), or one atmosphere. If you fill a zero pressure headspace with 14.7 psi of carbon dioxide (one atmosphere of CO2) you will have a mix of one ata (atmosphere) of CO2 and one ata of air, or a 50/50 mix. If the keg is near full the gases will mix almost instantly . . . venting to zero (one ata) will leave the headspace 1/2 filled with air. The next cycle (refill) will give you a 3/4 - 1/4 mix (CO2/air) . . . after burping/refilling your third cycle will be 7/8 CO2 and 1/8 air. You see how this goes. If you burp at 2 x 14.7 (call it 30 psi) your ratios will be 1/3, 1/9, 1/27, etc.

    Before racking, typically the keg is partially filled with sanitizer and purged with CO2. This results in the keg being partially purged of air before you start racking the beer. If you attach a liquid QD to your cane and fill the keg through the liquid post with lid on and vented you'll benefit from having less oxygen in the keg to start with. Let's say you dump in some sanitizer and pressurize to 14.7, you'll end up with a 50% mix of CO2/air. This is what would be left in the keg after purging the sanitizer and venting the keg to zero. Oxygen is 21% of this figure. This would be the starting point in your headspace after racking into the keg. If you rack through an open lid expect a little more air to enter the mix.

    Practically, you can ignore everything I've said above. I purge my keg of sanitizer, rack in through liquid post, then burp 3 or 4 times with whatever pressure is on the tank (12'ish). This is pretty normal and works well.

    If you really want zero oxygen, fill the keg completely with water (sanitizer) and purge with CO2.
    Liberatiscioli and billandsuz like this.
  7. Seacoastbrewer

    Seacoastbrewer Aspirant (212) Jun 5, 2012 New Hampshire

    Not sure if this is splitting hairs, but assuming there is some Oxygen in the headspace of the keg, would applying co2 pressure on top of this 'force' O2 into solution? Or maybe just a negligible amount given it normally takes around a week to carbonate at serving pressure?

    I'm imagining a scenario where a homebrewer is burping his keg at 30PSI, forcing more O2 into solution.
  8. billandsuz

    billandsuz Disciple (308) Sep 1, 2004 New York

    No danger.

    The addition of CO2 will not force oxygen, or any gas, into solution. The pressure of the oxygen is independent i.e. adding CO2 gas is not going to increase the amount of oxygen molecules already there.
    But you can force the oxygen out of the headspace by evacuating the gas with help of the prv. Releasing pressurized CO2 will carry oxygen with it, and the regulator will replace the space with pure CO2.
  9. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    So first time doing this opening the lid and siphoning from the fermentor lots of oxygen exposure unfortunately. Low carb shoot probably 7-8psi at about 35 degrees x 5-7 days and adjust as needed.

    Just wait till I see the bar on my regulator rise 1-2 points until purging 3-5 times?
  10. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    Do the purge/burp/repeat immediately after you rack to the keg. The idea is to get rid of the O2 as soon as is practical with your equipment. Then set it to serving pressure and drink something else for 7-10 days.

    BTW, the regulator's job is to maintain the pressure you set it to. It's not going to rise 1-2 points unless you tell it to. And it will rise immediately - there's no waiting involved. Assuming the reg and gauge are working properly, the gauge will be rock solid for the duration.
    billandsuz likes this.
  11. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    So as far as burping goes do it before I turn on the CO2.

    Do it while the CO2 is running as well to clear excess oxygen?
  12. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    You can't burp it without pressure. You need to turn on the CO2 first.
    I pressurize, turn off the valve (at the regulator, not at the CO2 tank, though, assuming you have check valves, that will work just as well. Otherwise, you'll be burping all the kegs.), burp, open the valve, pressurize, close the valve, burp, ...[you get the idea]. It's probably not necessary to open and close the valve each time, it's just a habit I've gotten into. And it audibly separates the pressurize/burp steps.
  13. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    So we are kegged no leaks. Having issues I want to keep the carb low 2.1ish. I'm having issue the pressure keeps rising to 10 and sticking.Need it to stick at 7.

    Any help here or is it something that may settle over the week? Or am I just stuck at 10.

    Used a screwdriver and can't turn down the pressure screw any further.

  14. billandsuz

    billandsuz Disciple (308) Sep 1, 2004 New York

    the lock nut is loose right?
    burp the keg with the gas applied. the needle will drop and then slowly rise. you will need to make very minor adjustments to the screw to get from 10 to 7. regulators do get squirrely at low pressure settings but you should get 7 psi with a properly functioning device.

    make sure your liquid temp is at 38. it wont have any effect on the regulator but if the temp is off and you want 2.1 vols, you wont get 2.1 vols.
  15. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    Close the valve and burp the keg. Set the regulator to 7 and open the valve. If it creeps back up to 10, then the beer is probably overcarbed (that also means you don't have a check valve, but that's not causing this problem). The gauge reads the pressure in the headspace, which will go back up to 10 as the CO2 escapes the beer to fill the lower pressure in the headspace. It's that pesky equilibrium thing. Leave the gas off and burp the keg a few times over the next few days. Go ahead and serve it using head pressure to push it if you like. After a few days, turn the gas back on and see if it settles closer to what you're looking for - that'll take a day or two (this is not a good time to be impatient). Leave the regulator at your desired pressure and it will straighten itself out in time.
    Liberatiscioli likes this.
  16. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    Will do. It's always something.... everyday brew learn something new and how to deal with it!
  17. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    Here`s and update I purged a couple more times closing the gas valve before bed last night.Held at about 9 psi. I turned the gas back on before I went to bed to see what would happen in the morning and it did hold at 9 psi overnight.

    I know its still early but if I increased the fridge temp to 41-42 that would put me at my target of 2.1 ish vol of CO2. Would this work or do you think I will be battling the equilibrium of pressures in my keg for a while?
  18. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    If it holds at 9 psi, then it's a pretty safe bet it's stabilized at that pressure at that temp. Be aware that, if you increase the temp, the pressure will rise (as the beer warms over a period of hours -- there's no such thing as instant feedback here). At that point, I would recommend setting the regulator to whatever the charts say it should be for 2.1 vols at 42F and let nature take its course over the next few days.
  19. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    Just came home from work still stable at 9. I guess the issue is I can't screw the regulator screw anymore to decrease the psi further.

    So I shut the gas valve. Burped the keg. I'll let it sit tonight/overnight see if any other pressure can get de gased later. Then turn the gas back on tommorow or so and see what happens.
  20. mikehartigan

    mikehartigan Aspirant (295) Apr 9, 2007 Illinois

    As long as it's connected to the keg and the valve is open, the gauge will show the pressure in the headspace no matter how much you turn down the regulator. Close the valve on the regulator and adjust it with the valve closed. It should vent the excess pressure in the regulator body, allowing you to lower the setting to, say 7 psi (just an example). Once you do that, leave it there. Open the valve and the gauge should rise back to 9 psi. Don't worry about that. If you want it at 7, burp the keg to lower the pressure. The gauge should drop to 7, but it will eventually rise again, to 9 or a little less. Burp it again. It will eventually rise to, maybe 8.5. Do it again, and it'll rise to 8. Do it again and ... (you get the idea). This all takes time - likely days. So patience is a requirement. If it helps, you lose nothing by drinking it during this time. Burp it every few hours until it stays at 7. Just don't touch the regulator.
  21. Liberatiscioli

    Liberatiscioli Devotee (416) Oct 3, 2013 Pennsylvania
    Beer Trader

    Cool can't wait to drink it!

    I appreciate the help! Will keep messing with it
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