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SiriusDG

Pressure Test

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On a separate thread, some of us have been discussing trying to do a Cask Ale. The trick is, you ferment, carbonate, and serve all from the same vessel; but you do not add priming sugar, so carbonation, while there, will be lower. So, we have to have a secondary, that is pressure capable to some degree, and can be tapped.

If I had something I thought could be adapted to work, the only think I am unsure of is the pressure part. So, if I wanted to create roughly half the pressure of a normal homebrew as a stress test for this container, I was thinking just put some water in, toss in some AlkaSeltzer, and screw on the lid, and stand back. Now when you stop laughing, here is the question...how much? How much water/AlkaSeltzer would it take to pressurize, lets say a one gallon vessel, to about half a normal beers pressure?

Any suggestions gratefully accepted here...if it works, I will gladly post all results.

David

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Mythbusters did a myth about using alka seltzer to escape from prison and they did pressure tests in small vessels to see if it was even plausible. Im trying to find the clip, it may help in some weird way.

Ok here are the clips. I havent watched them to make sure it was in there but I would guess that it is.

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Not sure if it helps, but I apply 12 PSI to any kegs in my kegerator wether it's store bought or home brew.

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Looks like one tablet got almost 2 psi. It also said that if you add two tablets you get more than four psi, so it gets kinda difficult, way beyond my comprehension.

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So, looking at all of this, sounds like 3 tablets should at least hit 6 psi, which is half of the stated carb level, which is my target. So, if the vessel survives 4 tablets, it should be good to go.

This makes my brain hurt a little...seems that a tablets ability to generate Xpsi is also related to the volume of the container...that is the part I am missing. I am looking at a 2.5 gallon container, and I plan on filling it almost completely with water, so the compressibly airspace should be quite small.

Experiment this weekend, stand by.

David

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Yeah, I know...and my resolve took a hit yesterday when I found out thatt after transfer to the cask, it has to age at least a month, since I was out to balance a pipeline with a fast ale...so this may or may not actually happen now. Technicallly, if I primary for two weeks and then cask for a month, that is still only 6 weeks, which if you follow 2-2-2, is the same. But I was hoping this would be more like a 2-2-Drink. :(

I may still do the pressure test tomorrow, and then decide later about casking. Stay tuned...

David

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Pressure Test complete. After a few safety trials with smaller amounts, the wally world 2.5 gallon slimline was filled to the 2.5 gall line with water, leaving about 1/2 inch headspace, and then 7 alka-seltzer were dropped in. Assuming correctness of research data, this should have created at least 14 psi, well above normal beer pressure levels. No damage occurred, and no apparent leakage either. The bottle swelled up a bit, and was firm to the touch, like a PET. It maintained pressure and shape for over two days, and the alka-seltzer water inside had fine bubbles on the inside of the plastic the entire time, although when finally tapped, the alkaseltzer mix itself was not really carbonated; not sure if I should have expected it to be or not?

Anyway, the beer is in primary, will keep everyone posted as this progresses.

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Assuming correctness of research data, this should have created at least 14 psi, well above normal beer pressure levels.


I'm not sure I totally agree with this statement... We carbonate beer at room temperature (say, 70 F), right? So an average beer (containing 2.5 volumes of CO2) will require 28.8 psi to fully carbonate. But I think I remember you saying that you were shooting for about half that level of carbonation for this guy, right?

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Yes, you are right...but I also was told by someone here that they pressurized their kegs to 12 psi, which is where my working number was coming from. However, even if I take your number, I can still get halfway there.

Bottom line...the beer is going in there. If it explodes, I will be very sad. Otherwise, if it leaks, I will get what I get, and unless it is totally flat, me and my friends will drink it and enjoy it and report back to the borg on how the experiment worked.

David

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Bottom line...the beer is going in there. If it explodes, I will be very sad.


Nice.

I also was told by someone here that they pressurized their kegs to 12 psi, which is where my working number was coming from.


Yep, that's how I carbonate kegs as well, but that's the proper temp for carbing at cold temps (38-40 F). The pressure required to carb at room temp (about 70 F) is much higher...

I will get what I get, and unless it is totally flat, me and my friends will drink it and enjoy it and report back to the borg on how the experiment worked.


Right on. At the end of the day, a proper cask should have much lower carbonation anyways, so hopefully you wind up in the right range. :)

:chug:

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Hey, perfect timing. I just checked on this bad boy...about 48 hours into the cask. Cask is bulging and very firm. I will probably put the entire thing into a large plastic bin, just in case...at two days, I am nervous.

Okay, so 12 PSI at COLD temps...so does that mean I would do better with this in the fridge? However, it is currently only 9 days post pitch...so, while it is already in the sealed cask, it is also still fermenting; so my brewers thinking is, I can't put it in the fridge yet, maybe 3 more days, then cool it off for a few weeks?

David

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Okay, so 12 PSI at COLD temps...so does that mean I would do better with this in the fridge?


Quite frankly, I don't know. How much priming sugar did you use for 2.5 gal?

Here's the thing: Carbonation primarily depends on pressure and temperature. At 70 F, if your vessel has a constant pressure of 14.3 PSI, you'll wind up with 1.6 volumes of CO2. If no additional pressure is applied, and you put that keg in the fridge (40 F), the pressure will drop to about 3 psi, but you'll retain the same level of carbonation (1.6 volumes). The million dollar questions are:

1) What is the pressure in that sucka right now?
2) Is there any more food in there? Or, will the yeast produce any additional CO2, which will cause the pressure to increase?

I don't know if you can really answer either of those questions (well, you might be able to find out if there is any yeast food left, but you'll introduce another question: how much did the pressure drop by drawing a sample from the container?).

I'm sure that info doesn't help you decide what to do... but there it is.

it is also still fermenting; so my brewers thinking is, I can't put it in the fridge yet


I think you're absolutely right about that.

If I were you, I'd try to figure out a guestimate of what the max pressure in that thing might be. What was the gravity when you racked it in there, and what is your expected FG?

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Yup.

Well, no priming sugar, that was the whole deal with racking to secondary early and just taking what the secondary gives.

Is there sugar left? I would guess yes, as this is only day 8 of fermentation. How much will pressure still go up? No clue, and taking a sample really won't tell me that anyway.

How much pressure is there now? I would guess close to a normal PET...it was really soft when racked, and is pretty danged firm right now.

Million dollar questions:

1) When this thing gets (close) to terminal pressure, will it A. Vent gently to equalize, or B. Explode violently.

2) How fast can I put it in the fridge and still have good beer a month from now. (I think this is the same as one of yours, just worded differently) ;)

David

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I'm a little late to the party, but I can't help myself.

Hand Pumps, Beer Engines, Real Ale, etc. are trendy in my city. MANY bars have them, and all the local breweries supply them. I learned about them last summer, and asked about the process while on a microbrewery tour.

They actually filter the beer, then some gets force carbed in kegs and bottles and some gets put into a closed vessel and reintroduced with yeast & wort (like bottle carbing, but batch carbing). Basically, it's "live beer" like we're already making.

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Well, I really have to argue against what you say. Not that that is not what they told you, or what they do...but they are cheating. The whole real point is:

1. NO FORCED CARB, AT ALL
2. Served out of the vessel it was fermented in

I don't think bottling, kegging, or racking to a new vessell and re-introducing yeast and sugar, aka priming, pass the smell test for number 2.

For the rest of the history on this, be sure to check this thread as well...

http://community.mrbeer.com/index.php?option=com_kunena&Itemid=58&func=view&catid=20&id=47337

And as for an update, the keg is now in the fridge, the beer is coming along nicely, although a bit more hoppy than I would have preferred, but still a bit of aging to go.

David

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Nobody asked, but my $0.02 is this:

The process you're describing Dave, is more traditional, but I can understand why a brewery would follow the procedure that Eddie described. If you're a purist, you might say "That's not REAL real ale." But is sure isn't draft beer either, so...

Like with so many aspects of brewing, there are a multitude of ways to get to the same end (tasty beer. or in this case, tasty cask-beer), and if 2 different methods achieve a similar result, I don't think it's fair to say one method or the other is "cheating."

That said, there's a brewer here in Tucson that does some cask conditioned ales, but when it comes time to serve them, he'll just plunk them down in his walk in next to all the serving tanks and push them through a creamer faucet with nitrogen. It is WAY non-traditional, and I frankly prefer my cask ale served more traditionally (gravity or hand pump, at warmer temps), but I can't really argue with the fact that it works for him.

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Yeah, that may have sounded more harsh than I intended. And for those who have not been here from the beginning, when this whole conversation got started a month or so back, I asked "What is the real difference between 'Cask Ale' and what we already do?" and the answer certainly depends on who you ask and whose opinion you value.

At this point, I am just havin fun takin a swing at it, and happy that my "cask" did not explode all over the brew room before I could move it safely into the fridge. :ohmy:

David

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