Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Repressurizing Kegs?

  1. Jul 25, 2010 #1
    I'd figure a thread in a forum with my fellow engineers would be a good place for a drinking question :P

    So my buddy's b-day is coming by soon, and we wanna surprise him by giving him a keg of our home brewed cider, he loves that stuff

    However, I've been trying to find out how we can repressurize the keg, so we can actually get the cider out, but I haven't been able to find anything.

    Would anyone know anything about this or have any links on how to fill up the kegs with our own brew?

    Thanks in advance for any answers :D
     
  2. jcsd
  3. Jul 25, 2010 #2

    Danger

    User Avatar
    Gold Member

    I must admit that having tended bar for over 20 years, I have never seen cider dispensed from a keg. That is, however, beside the point.
    A keg works on the siphon principle, the same as an aerosol can. The "exhaust port" (for lack of a better term) is located at the bottom. I suppose that the proper engineering term would be a "sump". An overpressure provided by a CO2 canister, powered compressor, hand pump, etc. forces the liquid up through the pipe to the faucet on the outside.
    That is, of course, assuming that your interest is in a modern keg as is used in drinking establishments. The old style such as held rum on sailing ships or ale in a tavern were strictly a gravity-fed system with the tap at the bottom.
     
  4. Jul 25, 2010 #3
    Yeah we are planning on using your normal run of the mill Keg.

    We have a tap, the keg, and the cider. We're just confused as to how it all goes together.
     
  5. Jul 25, 2010 #4
    A stainless steel 15.5 gals keg? Like Miller Brewing Co.?
    or
    a soda/cornelius keg, most commonly 5 gals?

    How much cider do you guys have?

    I own and have used cornelius kegs, and they're not difficult.

    Have not used a 15.5 gal keg for storing homebrew, but did find this at wikihow.
    Code (Text):
    [PLAIN]http://www.wikihow.com/Tap-a-Keg
    [/PLAIN] [Broken]

    Found this on YouTube on filling a steel keg.
    Code (Text):
    http://www.youtube.com/watch?v=KfRAFIYZd4M
     
    Last edited by a moderator: May 4, 2017
  6. Jul 25, 2010 #5

    Danger

    User Avatar
    Gold Member

    Harelo, it appears that Insanity has a pretty good handle on this (better than mine, at least), so I'm going to bow out of the conversation. No matter how you resolve the keg issue, I hope that you and your friends have a great time.
    It will be my pleasure to encounter you in another thread sometime in the future. Now, go drink some beer and kick some ***. :biggrin:
     
  7. Jul 26, 2010 #6

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    Go to the local brewing shop and buy/rent a brewing CO2 canister and associated fittings. This will provide sufficient pressure to protect and dispense the cider without carbonating it or damaging the pressure vessel.
     
  8. Jul 26, 2010 #7

    Danger

    User Avatar
    Gold Member

    And yet again I learn something from you. I always thought that CO2 would carbonate any liquid that it came into contact with. My sole experiment along that line came in the form of trying to revive a glass of flat Coke by introducing a straw between the liquid and the barrel of my Crossman gas-powered pellet pistol and then manually cracking the valve. I have no idea of whether or not it re-carbonated the Coke, because I couldn't find most of it. The net result was an empty glass, a messy table, something sticky dripping from my eyeballs, and one very pissed-off mother.
     
  9. Jul 26, 2010 #8

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    Good times!

    I have no idea how much pressure is actually needed to carbonate water, but it's somewhere between 'Brew Mart' and 'Soda Stream' CO2 canisters!
     
  10. Jul 26, 2010 #9

    Danger

    User Avatar
    Gold Member

    I'll have to look those up, since the names are unfamiliar to me. We have 3 readily available types of cartridges in Canada. There are wee ones for pellet guns, somewhat larger ones for paintball game markers, and life-raft inflators. The latter could cause an elephant to explode.
     
  11. Jul 26, 2010 #10

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    I'm sure they expand to soft drinks too, but your area of expertise is more oriented towards weapons and survival!
     
  12. Jul 26, 2010 #11

    Danger

    User Avatar
    Gold Member

    True that.
    You did remind me, however, that some pop and beer dispenser systems still use CO2 canisters. (I even mentioned it in my first post here, and then forgot about it. :rolleyes:) It pretty much slipped my mind for two reasons. One is that they aren't high-pressure units. Only about 250 psi or so. (Okay, I wouldn't want to wrap my lips around the valve, but it's still insignificant compared to the 1,200 psi or so that a Crossman cartridge packs.) The other reason is that the last couple of bars that I worked in didn't use them. We had something called a "carbonator". I honestly don't know how the damned thing works. It is virtually indistinguishable from a small air compressor. Somehow, it extracts CO2 from the ambient air, compresses it, and injects it into the drink system. In fact, if someone will explain to me how it performs that separation I will be most thankful. It operates too fast for the process to involve chemical adsorption or absorption, and the whole thing would fit in the proverbial breadbox. I haven't dwelled upon the matter to any great extent, but it has always puzzled me.
     
  13. Jul 26, 2010 #12
    When I started force carbonating beer in soda kegs, I read that about 5-7psi over a few days is sufficient. Hook up the co2, set regulator to 5-7psi, turn on the co2 and give it a few days to "soak" in. It is possible to do it faster, like I did my first time and misread the regulator, and pressurized it to ~100psi. The max rating for a soda keg is ~120-130psi I believe. Anyways, the beer was carbonated damn quickly, and I had to open the quick release valve to bleed off the excess pressure, and when I connected the dispenser hose, it blew the faucet right off and sprayed beer everywhere until I managed to disconnect it.

    Really only need ~2-3psi is needed to push the beer/cider, and a little more to carbonate it. If want to carbonate faster, maybe go 10-12psi at the most. Don't go over 15psi as its unnecessary and creates too much foam in the cup, even 10psi can be foamy. Definitely do not do 100psi. Low psi is better. You can always increase it too your liking, but kinda hard to do the opposite.

    I did have the opportunity to hear from Jeff Carlson from Primetime Brewers last week. He is 4 times cider maker of the year, and he personally carbonates his cider just so there are a few bubbles, so maybe just 4-5psi for a day or two then bleed off the excess, then when serving, use 2-3psi to dispense it.

    When pressurizing, when you first seal the keg, I'd suggest you go 1-2psi until its pressured. Then open the valve if it has one, bleed it off, the pressure again, and repeat a few times. Ensures that the oxygen is removed and only co2 is in the keg. Oxygen skunks beer fairly quickly and probably cider too. Alcohol gets converted to vinegar by acetobacteria in the presence of oxygen.
     
  14. Jul 26, 2010 #13

    Danger

    User Avatar
    Gold Member

    You have a gift, Insanity. This thread is about a subject that I honestly had very little interest in. I responded to it only because I thought that my 20+ years of bartending experience might be of benefit. (Not the first time that I've been wrong.) There is something about the way that you post, however, that intrigued me and instilled a desire to learn more. If you aren't a teacher in your real life, you should be.
     
  15. Jul 27, 2010 #14
    I am not a teacher professionally, though I did do some subbing this year, barely tolerated it. If I were teaching to those who wanted to learn, I'd probably enjoy it. But in the public schools here, not.

    what more would you like to know? I've been brewing for ~6 years, many different styles of beer, and even some of my own. I mostly don't buy beer anymore, except in brewpubs, as I simply make my own. Often its a lot cheaper and I make better stuff. I figure I could brew 5 gallons of a pale ale for ~$10. Nowadays its $7-8 for a six pack of any craft beer.

    Do not mention Budweiser or Miller as an option for me.
     
  16. Aug 4, 2010 #15
    nice, my barley wine is finishing around 10.91% ABV.
    :smile:
     
  17. Aug 4, 2010 #16

    turbo

    User Avatar
    Gold Member

    I should start brewing again. Back in the late 70s, I made all my own beer and bottled it in the tough old "swirl" Pepsi bottles that could stand the pressure from my aggressive carbonation process (all natural, BTW). With the cost of the malts, sugar, yeast, caps, etc, my home-crafted beer came in at about eleven cents a pint. It was as strong or stronger than wine. The old fellow that taught me how to home-brew used to say "Drink one of these before supper and you won't remember what you had for supper. Drink two before supper and you won't remember if you had supper."

    The trick was to let the beer go almost flat in the crock when brewing, then put sugar-water syrup into each bottle before filling and capping, so that the yeast had a new source of sugar for alcohol production and carbonation. Needed the heavy Pepsi bottles to take that pressure. Chill and handle gently before opening, or you'd get a surprise.
     
  18. Aug 4, 2010 #17
    Wow how do you brew your own beer? I've always wanted to!!
     
  19. Aug 4, 2010 #18

    turbo

    User Avatar
    Gold Member

    It's really easy, but a bit more than I want to type right now. There are lots of places that sell brewing supplies, but they are often high-priced scams. You can do a lot with an old stoneware crock with a cover (on a raised pedestal to facilitate siphoning). Blue Ribbon malts in large cans are a good way to start supplying flavor to the brew.
     
  20. Aug 4, 2010 #19
    Indeed, been told I brew very good beer. Most important thing is keeping equipment clean and sanitized, or risk getting foreign bacteria or yeast growing in the beer.

    I would not suggest a Mr. Beer or Beer Machine kit. I have several glass carboys, 5 or 6.5 gallons. They look like the water cooler jugs, except glass.

    It's not too difficult to make good beer.
     
  21. Aug 4, 2010 #20
    I am fortunate that the local brewpub and brewing supplies is quite reasonable with prices.
    Hops are $1.60 to $3.50 per oz depending on the type and pellets or whole leaf. Grains are usually $1.25 per lb or less if getting larger bags. The 55lb bags comes to ~$0.75/lb. Local water is very high in hardness and alkalinity, so I don't typically use it, and purchase water from Meijer's purified water station (Culligan's I think), refills are $0.29 per gallon. I then treat the water with some minerals additions if I desire so.

    I figured I can brew 5 gallons of a pale ale for ~$10-$12.

    I agree on the scams with Mr. Beer and Beer Machine. Read the instructions on a Beer Machine and it said nothing about sanitizing the fermenter or boiling the malt extract. Basically it was add water with the malt extract, fill to volume, add yeast and wait.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook