Sugar priming in a one-use keg, pressure issues

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Malloy

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Hi all,

I'm about to experiment with a Petainer one-use keg, and to keep costs down (and also because I find it more facinating) I want to prime the keg with sugar and let the beer do it's business.

My question is this, the kegs can take 4 bars of pressure so I want to be able to determine the WORST CASE SCENARIO pressure-wise. It depends on the FG of course, and the amount of priming sugar, both of which I can check and control. What I need (I think) is a table or a formula that lets me determine the upper level of pressure.

Anyone messed around with this, or have any suggestions (other than testing out the beer-bomb at the Christmas dinner...) to how this could be worked out?
 
Sorry if I'm not explaining my problem well enough.

In short I want to avoid getting the keg over 4 bar pressure, so I need to know how much sugar to use, but at the same time taking into account the FG. Let's say the FG is 1.014, I'm fairly sure the fermentation is finished, but I want to take into account that it is not.

So in this example, how much sugar would I be able to add to a 1.014 beer and still be under 4 bar even if it continued to ferment all the way to 1.000.

It's hypothetical, but the 4 bar max is real, and I can't risk going over :)
 
Let it ferment until you have a stable SG reading for several days. That's the only way to know that it's really finished, and you shouldn't be packaging until it's completely fermented, anyway.

I'd also be very surprised if it doesn't have some sort of pressure relief valve.
 
Generally when bottle conditiioning it's looked at as volumes of CO2 in solution and not pressure like we'd do in force carbonation. Your standard volume of CO2 for most beers is 2.5. You'd use an ounce of sugar per gallon if you're using 12 oz bottles. For a mass amount like a keg you use about 1/2 to 3/4 of that amount because of the headspace to beer volume ratio.

If you look at a force carbonation chart you need 29 PSI at 70 F to get 2.5 volumes. I'd say that would be the same pressure that would be in the headspace with priming. 4 bar is 58 psi so you would be fine.

Like Bishop said make sure it's done fermenting. You shouldn't have to take into account that its not
 
Generally when bottle conditiioning it's looked at as volumes of CO2 in solution and not pressure like we'd do in force carbonation. Your standard volume of CO2 for most beers is 2.5. You'd use an ounce of sugar per gallon if you're using 12 oz bottles. For a mass amount like a keg you use about 1/2 to 3/4 of that amount because of the headspace to beer volume ratio.

If you look at a force carbonation chart you need 29 PSI at 70 F to get 2.5 volumes. I'd say that would be the same pressure that would be in the headspace with priming. 4 bar is 58 psi so you would be fine.

Like Bishop said make sure it's done fermenting. You shouldn't have to take into account that its not

Wouldn't this make it over carbonated once chilled?
 
Wouldn't this make it over carbonated once chilled?

It's 2.5 volumes whether it's carbed at 36 degrees and 10psi or 70 degrees and 30 psi. Once you chill it and release the pressure off the keg it comes out at the same carbonation level. Bottles are at that pressure until they're chilled. If you open one warm you'll get a lot of foam. CO2 dissolves into liquid much better at lower temperature
 
Thank you all for your replies!

It's a 30-liter keg, but no pressure relief valve.

I am fully aware that 4 bar is alot of pressure and I don't want to get near that point.

I'll try using half of what I usually use, see where it ends up. :)
 
It's 2.5 volumes whether it's carbed at 36 degrees and 10psi or 70 degrees and 30 psi. Once you chill it and release the pressure off the keg it comes out at the same carbonation level. Bottles are at that pressure until they're chilled. If you open one warm you'll get a lot of foam. CO2 dissolves into liquid much better at lower temperature

Thanks. Makes sense.
 
After the beer is carbonated in the Petainer, how do you plan to use it. Drawing beer off will increase the head space, the head space will fill with CO2, reducing the carbonation level of the beer.
Do you plan on using your CO2 system to dispense after carbonation as the one way system is intended.
 
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