Relieving over carbonation.

[BigWilley]

What is the best or quickest way to relieve overcarbonation in a serving tank. I remember reading something about letting the head pressure off and then connecting a CO2 supply to the bottom of the tank and giving it a couple of quick blasts of gas to knock some of the carb out of solution. My memory is fuzzy on this process and I never knew anyone who did it so any suggestions would be helpful.
Thanks in advance
Big Willey

[rudge75]

The process you're describing is exactly what I do in this situation, just be sure to sanitize everything and bleed some co2 through the hook-up to purge the o2 out of the line. If you're using grundies, be sure to stand as far away as possible!

Play safe...
Dave

[flyinpig]

You are on the right track. If you are using grundy tanks as I do. Just blow all head pressure out of vessal then shut the valve. The head pressure will come back up then check. If it is really over carbonated you can give the bottom of the grundy a few good wallops with a rubber mallet and that works great.. Be very carefull when doing the wallop method especialy if the tops are clamp on. Hope this helps

Cheers
The Pig

[Bill Madden]

over carbonation

In response to BW,

I have heard of using CO2 blasts to overcarbonated beer in SV's but always felt that using the same gas to remove CO2 seemed problematic. I have resolved the very problem you describe by using Nitrogen. The lower molecular weight of N2 creates a nucleation point and strips CO2 out of beer quite effectively. Same situation, take top pressure off the vessel (or very low, we take it down to 5 psig) and blow N2 thru the carbonating stone to 15 psig. Works every time but unfortunately will strip some hop aroma and other qualities from the finished product. This is a last ditch effort for needing a brew sooner than being able to just take top pressure off to let nature take its course.

Cheers,

Bill Madden
Capitol City Brewing Co.
Arlington, VA

[Matthew Letki]

Bear in mind that by knocking C02 out of solution aggresively, you create a lot of foam in the serving vessel. This is a problem for two reasons. First, the foam will break down and form particles in the beer, these tend to look like small tan/yellow/green flakes. These will precipitate and can end up in the customers glass. Not good. Second, beer only has the ability to produce "Head" a limited number of times. From my experience, I have found that all malt beers can "Head" three times. The first is during fermentation, the last is in the customers glass so you only have one more time to let the beer foam up. In practice, I have found that exceeding two "headings" will cause the beer to lack somewhat in head formation and stability, exeeding three "headings" may leadto very poor head retention.

Another route that may work for you instead of changing dissolved CO2 quickly is altering temperature. If you can reduce the temp of your beer in the tank and lines, you may calm the beer down substantially.

Also remember that you cannot serve from a serving vessel if the pressure on the beer in the line (pressure from head of beer in tank [0.56lbs/foot] + gas pressure) is less than equilibrium of the beer as the CO2 will break out in the lines causing "spurts" at the taps and wet bartenders.

Cheers,
Matt

[BigWilley]

Overcarb

Thanks for the advice. My problem on this particular beer is that I have a 30BBl serving tank that takes a while to empty and due to extremely long lines the pressure is usually about 13-15 psi usually on the higher side. Towards the end of the tank it is inevetably overcarbonated and pours terribly. Compounding the problem are the beer lines themselves which are in bad shape. Years of under cleaning them before I took over have led to lines which i assume are pretty rough on the inside judging from the crap I get out during cleaning. Sometimes the beer pours worse after a good cleaning because i disturb the film of buildup. I am currently pleading my case for new lines but management is tight and it will be a while. Beer pumps or a gas blender would help but I need to prioritize and I would rather get new lines first. I also rely on bunging the fermentors for natural carbonation which sometimes comes out a bit high and with no way to test it I have to guess. Thanks for the info though, i hadn't thought of that.

[Matthew Letki]

A way to do it on the cheap might be to buy cylinders of nitrogen and "blend" your self, in the tank. Get your beer in the tank and then alternate between CO2 and nitrogen to "push" the beer with. As you get lower down the tank, use more nitrogen. This would be a lot cheaper than buying in beer gas, but you may need to monkey with it to find a programme that works perfectly.

Cheers,
Matt

[dick murton]

Re "I have a 30BBl serving tank that takes a while to empty and due to extremely long lines the pressure is usually about 13-15 psi usually on the higher side. Towards the end of the tank it is inevetably overcarbonated and pours terribly."

Only increase the top pressure whilst serving. At the end of each session, reduce it back to the equilibrium pressure, or possibly even a little less" It will cost a little gas, but should help carbonation consistency. I agree with Matt re nitrogen, but merely reducing pressure between sessions is easier to control, and avoids N2 pickup (minimal I admit) and changes in head characteristic from start to end of tank.

[brewsurfer]

If management is tight, you should plead your case from a cost savings perspective.

If foam is 70% beer, how much do the bartenders waste pouring beer from that tank? How much money can you save by eliminating the foaming problem? Can this pay for a nitrogen blending system? How many customers will you lose from serving beer from old lines? They should be replaced every year in most cases, and a brewpub should generate enough capital to make that possible.

I think that if you aren't pushing from this tank with mixed gas, you are seeing significant carbonation from gas in the headspace of the tank. Can you keg off the last few barrels so it doesn't overcarbonate in the tank?

I remember seeing a device at a trade show that could essentially make two beers from one tank by pinpoint carbonation or nitrogenation of the finished beer. (C.E. carbonation is in essence a preservative, so I don't think this should be used on a 30 bbl tank that takes a long time to empty.)

On the bunging issue: are you doing force fermentations of your worts to check for end point? That would help you to determine when to bung.

Eric Sorensen
p.s. check out this link if you haven't already: http://www.draughtbeerguild.com/

[Valleybrew]

I have to agree with the Nitrogen dispense system approach. I work at a small pub and we have a very long beer dispense line setup. Distance from serving tanks to taps is over 75 feet. Serving tank pressure is 18 psi. We used to use CO2 but on the slower selling beers we would have foaming problems toward the end of the tank, a real nightmare on a Friday night! We have since negotiated a great deal with our CO2 supplier (Sierra Airgas). They installed a Nitrogen generator for free. The unit mounts on the wall and runs off 110volt service. The unit compresses room air and using membranes produces Nitrogen which is stored in a reservoir. The unit blends the produced Nitrogen N2 with CO2 from our bulk tanks producing a 75% N2 / 25% CO2 gas which we push the beers with. I also can use the blend to Nitrogenate and serve my Nitro Stout. The only obligation is a monthly flat charge we pay for all our CO2 and equipment use of approx $200. We use much less CO2 each month now that we have the blender, we waste a lot less beer from foam and the beer flavor is much more stable without the over carbonation problem. My bartenders are very very happy with me and growler filling is now a snap.

Steve Altimari
Valley Brewing Company