Pressure in keg falling off at start

[doug293cz]

If I say I have a bottled pint of beer at 2.2 Volumes you'll know the mass of CO2 (other than arguments over pint vs pint)in solution, but you won't know the actual volume of the CO2 in solution without also knowing the internal pressure and temperature.

If I have a value, and I have to multiply that value by volume in order to know the mass of material that the value represents, then the value has units of density.

Brew on

 

[bracconiere]

It can't have much calories because it doesn't contain much energy.

if i were a tree i'd disagree...

 

[jddevinn]

if i were a tree i'd disagree...

If you were to cut up and then burn a tree you'd disagree

 

[johndan]

I’m sort of in awe at the direction this post has taken.

 

[Vale71]

This assertion really makes no sense. Use any brewing software or online carbonation tool. We need less CO2 when the beer is cold to carbonate to the desired level vs needing more CO2 when the beer is warm (warmer than the cold beer) to get the same level of carbonation.

Your assertion is wrong. You need the same amount of CO2 to carbonate to a given carbonation level regardless of beer temperature. 3 vols equals 5.88 g/l of CO2 at any temperature. The only thing that changes is the headspace pressure required to push CO2 into solution and to keep it there indefinitely. This all has nothing to do with how fast equilibrium is reached.

 

[Vale71]

i'm curious, does co2 have calories?

Only if you're a rare bacteria living near a vent on the ocean floor...

 

[Vale71]

Turning off a CO2 cylinder obviously doesn't "prevent leaks".

No, but it certainly reduces the extent of loss they may cause. The amount of CO2 that's inside a regulator is quite small compared to a full cylinder. Even if the leak were upstream of the check valve worst case would be your beer goes flat as the keg slowly depressurizes, but if you leave the shut-off valve open you may well end up needed a cylinder refill sooner rather than later.

 

[TLaffey]

This assertion really makes no sense. Use any brewing software or online carbonation tool. We need less CO2 when the beer is cold to carbonate to the desired level vs needing more CO2 when the beer is warm (warmer than the cold beer) to get the same level of carbonation.

More PRESSURE at higher temps, yes. Beer absorbs CO2 faster at the higher temp, but doesn't absorb as much of it. Beer will absorb more gas at lower temps. At a constant pressure, you will have more absorbed (more carbonation) at the lower temp.

 

[Vale71]

Beer absorbs CO2 faster at the higher temp, but doesn't absorb as much of it.

If you look at any carbonation chart you'll see that you can reach any carbonation level, no matter how high, at any temperature provided you set the correct equilibrium pressure. This means that beer can absorb as much CO2 at a higher temperature as it can absorb at a lower temperature. Saying that beer "doesn't absorb much of it" is simply wrong.

For the case we were discussing, i.e. pressurizing a keg at a given pressure and then shutting off the gas supply, you would observe a much faster drop in pressure at a higher temperature than at a lower temperature leading you to mistakenly thinking that there must be a leak somewhere and disassembling everything in a futile attempt to fix something that "ain't broken".

 

[johndan]

This is a fairly accurate summary of my general approach to everything!

… disassembling everything in a futile attempt to fix something that "ain't broken".

 

[TLaffey]

If you look at any carbonation chart you'll see that you can reach any carbonation level, no matter how high, at any temperature provided you set the correct equilibrium pressure. This means that beer can absorb as much CO2 at a higher temperature as it can absorb at a lower temperature. Saying that beer "doesn't absorb much of it" is simply wrong.

For the case we were discussing, i.e. pressurizing a keg at a given pressure and then shutting off the gas supply, you would observe a much faster drop in pressure at a higher temperature than at a lower temperature leading you to mistakenly thinking that there must be a leak somewhere and disassembling everything in a futile attempt to fix something that "ain't broken".

Yes, I agree. My wording was clumsy.