Priming in a 4liter keg question

[rayzor]

Hi

I just kegged some of my beer in a 4liter mini keg, and I added 4 heaping teaspoons of sugar. Is that about right, or is it too much?

I read somewhere that you should use 1/3 of the priming sugar used when bottling. Is that correct?

A little afraid that my keg will go nuclear on me :-/

Also...

Can I fill the keg all the way up to remove the oxygen, or do I need headspace(and then purge with co2)?

 

[jerbrew]

If you could hook up a pressure gauge on that keg you could monitor the pressure building in the headspace. You could then just treat it like carbing with a CO2 tank by releasing pressure if it gets too high. I have no idea about the amounts you used without consulting a priming chart and knowing how much carbonation you're going for and the headspace of that keg.

 

[WrQth]

1 tsp is about 4grams so 16grams total in 4ltr would give a about 1.9 volumes of CO2. Assuming your FG was stable, max temp after fermentation was 68F, and you used plain table sugar. That would be a little on the undercarbed side but would work for English style or Porter/Stout.

 

[rayzor]

If you could hook up a pressure gauge on that keg you could monitor the pressure building in the headspace. You could then just treat it like carbing with a CO2 tank by releasing pressure if it gets too high. I have no idea about the amounts you used without consulting a priming chart and knowing how much carbonation you're going for and the headspace of that keg.

Thanks! Yes, I have have a pressure gauge. I'll try that. Just got the keg and need more experience.

Read about a guy whose keg "exploded". Freaked me out

So, what are the chances that a 4liter steel keg, with 4 heaping tsp of sugar and no headspace could be damaged?

 

[rayzor]

1 tsp is about 4grams so 16grams total in 4ltr would give a about 1.9 volumes of CO2. Assuming your FG was stable, max temp after fermentation was 68F, and you used plain table sugar. That would be a little on the undercarbed side but would work for English style or Porter/Stout.

Thanks! Guess I'll add some extra co2 if it gets undercarbed.

 

[jerbrew]

So, what are the chances that a 4liter steel keg, with 4 heaping tsp of sugar and no headspace could be damaged?

If the keg is structurally sound then zero. those things are built to withstand several times greater than their intended working pressure. I think the rating is somewhere around 120 PSI

 

[rayzor]

If the keg is structurally sound then zero. those things are built to withstand several times greater than their intended working pressure. I think the rating is somewhere around 120 PSI

So, it's possible to prime the keg with no headspace to get carbonation, like you normally would? Put in another way, if the keg is solid enough, the headspace is not needed?

 

[jerbrew]

So, it's possible to prime the keg with no headspace to get carbonation, like you normally would? Put in another way, if the keg is solid enough, the headspace is not needed?

what i'm saying is that with the amount of sugar you put in your keg should be fine. Just as long as you're not using some janky junk yard keg that hasn't been pressure tested in 60 years.

the amount of CO2 produced by that amount of sugar is constant (as mentioned above I think they said 1.9 volumes). The yeast will gobble up the sugar produce CO2 and then stop. The headspace will determine what pressure that amount of CO2 will produce in your keg. And since your beer will be absorbing the CO2 it will be reduced as it dissolves into the liquid. Think about it this way. The reason the headspace of a bottle when you fill it is important is becasue of the amount of pressure that's produced in that headpsace from the amount of CO2 created by the yeast. If you were to leave half an empty bottle then the pressure is greatly reduced, not enough and you risk over pressurizing the headspace. But, you have the same amount (mass moles take your pick) of CO2. Jump back to some GenChem and you might remember P1V1=P2V2 that's all that is happening here. change your volume and you change your pressure all other things constant.

That being said, If you're priming in your keg and you get to a pressure that gives you a nice carbonation and you tap that keg. Then unless you have it hooked up to a CO2 source (tank and regulator) your beer will start going flat. Pretty much like drinking half a bottle and recaping it (not a perfect analogy but close enough)

I hope any of this helps and doesn't just sound like it should be in the drunkin ramblings threads.

 

[rayzor]

what i'm saying is that with the amount of sugar you put in your keg should be fine. Just as long as you're not using some janky junk yard keg that hasn't been pressure tested in 60 years.

the amount of CO2 produced by that amount of sugar is constant (as mentioned above I think they said 1.9 volumes). The yeast will gobble up the sugar produce CO2 and then stop. The headspace will determine what pressure that amount of CO2 will produce in your keg. And since your beer will be absorbing the CO2 it will be reduced as it dissolves into the liquid. Think about it this way. The reason the headspace of a bottle when you fill it is important is becasue of the amount of pressure that's produced in that headpsace from the amount of CO2 created by the yeast. If you were to leave half an empty bottle then the pressure is greatly reduced, not enough and you risk over pressurizing the headspace. But, you have the same amount (mass moles take your pick) of CO2. Jump back to some GenChem and you might remember P1V1=P2V2 that's all that is happening here. change your volume and you change your pressure all other things constant.

That being said, If you're priming in your keg and you get to a pressure that gives you a nice carbonation and you tap that keg. Then unless you have it hooked up to a CO2 source (tank and regulator) your beer will start going flat. Pretty much like drinking half a bottle and recaping it (not a perfect analogy but close enough)

I hope any of this helps and doesn't just sound like it should be in the drunkin ramblings threads.

Helped a lot. Thanks