First time corny user

A forum to discuss the various ways of getting beer into your glass.
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Juffer
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First time corny user

Post by Juffer » Mon Mar 02, 2020 9:55 pm

Hi all, I'm going to be using a corny for the first time and i understand the temperature and psi chart and how to gas it. What i am unsure about is once i have carbed and i want to store it for a few weeks for a party for example do i leave it with some pressure in the keg or purge it all out?

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PeeBee
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Re: First time corny user

Post by PeeBee » Tue Mar 03, 2020 1:16 am

If you vent the pressure, a few hours later the pressure is back. Less a bit. The pressure in the headspace keeps the carbonation in the beer, so you don't want to vent it. Harder to understand is the gas keeping the carbonation in has to be the same (CO2). You can't carbonate the beer by maintaining nPSI of CO2 then once carbonated replace the nPSI of CO2 with nPSI of, say, nitrogen 'cos that wont work (rules of "partial pressure").
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Jocky
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Re: First time corny user

Post by Jocky » Tue Mar 03, 2020 8:15 am

Once it’s carbonated then you can just remove the gas and store it. It’s sealed so the gas is going nowhere. In fact I’d recommend taking it off the gas when not carbonating or serving as a slow leak can empty your CO2 bottle.

Before you serve you’ll need to get the keg back down to your carbonation temperature or when you pour it you’ll end up with nothing but foam.
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Re: First time corny user

Post by IPA » Tue Mar 03, 2020 8:40 am

Why not use it as you would any other keg ? There is absolutely no need to spend money on gas to force carbonate. Prime it with a maximum of 2.5 g per litre of household white sugar seal the lid with a burst of gas and leave two weeks to carbonate. Invest a couple of quid in a short gas tube and a float take off and your beer will pour crystal clear. Later on you might wish to buy a spunding valve in order to control the internal pressure
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Kev888
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Re: First time corny user

Post by Kev888 » Wed Mar 04, 2020 2:10 pm

To echo some of what has already been said: to store the beer then yes, just disconnect the gas but leave the keg pressurised.

If you vent it then the carbonation will reduce a bit, but also the lid may fail to stay sealed (and in that case lose most of the carbonation over time). Corny kegs are designed for internal pressure to push the lid tight against the neck rim, the spring clamp on the lid is really just intended to hold it in place beforehand. Which is partly why even if priming, an initial boost of CO2 pressure is still advisable - to make and keep the lid's seal until the pressure builds naturally.

Alternatively, leaving it connected to the gas supply after the beer has reached equilibrium wouldn't gain much. But it might cause problems if there were a leak, and also if there were any drops in temperature - since more CO2 would be fed in, leading to greater carbonation than intended. If the keg is merely sealed, the amount of CO2 in the keg can't change even if temperature (and so pressure) varies.

Assuming the yeast have finished anyway. Sometimes they can continue working away 'very' slowly on residual sugars, making a bit more CO2 after kegging. Or heavily dry-hopping the keg can cause a similar effect via hop enzymes and hop creep. In those cases the beer might exceed the original equilibrium level and be more carbonated than expected when it comes to serving, so if in doubt periodic checking of stored keg pressure with a gauge or spunding valve on a gas disconnect can be useful.
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Re: First time corny user

Post by Juffer » Wed Mar 04, 2020 6:20 pm

Thank you everybody for your replies. So if i gave it 12psi of co2 i could leave it for x amount of time until i drink it? Its a lager im brewing for 5 weeks time.

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Re: First time corny user

Post by Kev888 » Wed Mar 04, 2020 6:37 pm

12psi should be more than sufficient to maintain the seal. Though sometimes a rather higher blast, say 20psi or so, can help the lid to seat better - especially with older or more battered kegs - so that would be my own preference. It should be sufficient for carbonated beer, or beer that has been primed and will soon create its own pressure and carbonation.

But if the beer is to be stored uncarbonated, or is to be chilled after sealing up, then it could be worth periodically checking the pressure hasn't dropped too far - due to the CO2 being absorbed by flat or cold beer. Depending on the condition of the keg (some are better than others), dipping below several PSI might be at risk of allowing the lid seal to break.
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Re: First time corny user

Post by Jocky » Wed Mar 04, 2020 7:45 pm

Like Kev has said, get the beer carbonated first, then you can unhook it from gas for storage.

Personally I can’t leave my gas connected the whole time (yet) so I initially give the beer 35 psi (at 5c), top up again a day later, then just top it up if it drops below the final serving pressure until it stops dropping below the serving pressure.
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