Carbonation-Why Vent?

[d_striker]

I have asked many brewers that vent while carbonating, why they vent. I have not gotten a single answer that makes sense.

As brewers, we all know that CO2 solubility in solution is dependent on temperature and pressure. So running CO2 through the stone while venting makes absolutely no sense to me.

Running CO2 through a stone on a capped vessel, building pressure to a certain point, and then venting makes absolutely no sense to me.

For you brewers that vent, why are you venting?

[briangaylor]

Let me throw my hat in the 'dont constantly vent while carbing' category

[d_striker]

Let me throw my hat in the 'dont constantly vent while carbing' category

Do you vent at any point?

[3guysandabeerd]

from what I understand is that it help move the co2 throw the beer faster im guessing some say they can carb beer in a few hours. in the end your wasting your co2 and money here a link that help me out a ton and its the method I use the only thing I cant do is spud me beers at this time http://discussions.probrewer.com/sho...l-to-2-volumes
hope this helps

[grovesj]

As I understand the only reason to vent while carbonating is to scrub out undesirable characteristics (sulfery/diacital) and reduce 02 levels that might have got picked up in transfer. Unfortunately you will also scrub out hop aroma. I don't do it but if I needed to get rid of some funky notes to save a beer I have that in my back pocket and would give it a shot. Better than dumping a batch or worse serving a beer that isn't up to my standards.

[NHBrewer23]

Why constantly vent? Don't.

A few breweries I have worked for would constantly vent their tanks while pumping in CO2. The claim was that the beer would carbonate faster. All this did was strip away some great aroma. With that said, I do slowly vent for the initial 15-30 minutes to help scrub any O2 pick-up during my transfer. Without having an O2 meter, it is hard to quantify if this practice has any benefit. It makes me feel a little better.

I have worked with some brewers who were never taught about the wetting pressure of their carbonation stone and the effects of hydrostatic pressure. It was not uncommon for the brewers to believe the faster the CO2 went into the tank, the faster they would carbonate. They would crank up the regulator to 30+ psi and start ripping through the beer. Obviously not all this CO2 was being dissolved so the tank would need to be vented to prevent the PRV from going off.

Anytime you purchase a new carbonation stone, you will want to see how much pressure it takes for the CO2 to break thru the stone. This is easily accomplished by placing the stone in a bucket of water and slowly raising the CO2 pressure using a regulator. Once bubbles are emerging from the stone, note the pressure on the regulator. This is your wetting pressure (7-12 psi). As for hydrostatic pressure, for every 28 inches of beer above the carbonation stone, there is 1 psi of pressure pushing down on the stone. Therefore, if your wetting pressure is 7 psi and you have 28 inches of beer above the stone, you will need to supply 8 psi of pressure just to get CO2 into the beer.

Once you know your wetting pressure and how much hydrostatic pressure you have in the tank, you will need to measure the temperature of the beer. Using a carbonation chart, look up the temperature of your beer and correspond that with PSI required to obtain your desired carbonation level. You will want to set your CO2 regulator to PSI required plus your wetting pressure plus the hydrostatic pressure. For instance, if your beer was at 34 degrees and you wanted 2.57 volumes of CO2, your required PSI is 11. If your wetting pressure is 7 psi and you have 1 psi of hydrostatic pressure, you will want your CO2 regulator set to 19 psi. Once the pressure gauge on your bright tank reaches 11 psi, your beer should be carbonated to 2.57. You will want to measure to confirm.

Carbonating is not quite an exact science as instrument calibration as well as carbonation stone cleanliness can impact results but no matter what, there really shouldn't be a need to constantly vent.

[SeattleBrewer]

Constantly venting is about keeping bubbles moving through the beer during carbonation. I've used the non-vent method many times and consistently would undershoot the Co2 volumes by 0.2 Ben following the above method to the last detail. Moved to venting method with no difference in aroma or flavor and with more consistent results in less than an hour. The main thing to remember when venting is to just let out enough gas to keep gas moving through the stone. Any more than that and you are wasting gas and time. I always pressurize the tank to just below PRV blowoff (around 13-15 psi) then set the regulator to whatever hydrostatic and wetting pressure tells me it needs to be, then let it go while slowly venting. Typically I can hit 2.5 volumes in 45 minutes with 35 degree beer.


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[SeattleBrewer]

I should elaborate a bit: the non-vent method assumes 100% absorption of CO2 by the beer. In reality, that is not the case. So you could do the non-vent version and verify with a precision instrument like a borrowed Zahm SS-60, and adjust your targets based on your readings. For example if 35 degree beer at 11 psi head pressure SHOULD be at 2.5 volumes, but you read 2.3 volumes after carbing, then shoot for the 2.7 head pressure next time and you should fall closer to 2.5. With trial and error and good record keeping you could do the no-vent carb and hit your targets fairly consistently. For what I've experienced as a production brewer of six years in high-volume breweries, carbing for most of a day or more is not practical or possible. Sometimes you have to get a beer carbed and racked in 2 hours to fulfill orders.


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[beerdweeb]

?

I should elaborate a bit: the non-vent method assumes 100% absorption of CO2 by the beer. In reality, that is not the case. So you could do the non-vent version and verify with a precision instrument like a borrowed Zahm SS-60, and adjust your targets based on your readings. For example if 35 degree beer at 11 psi head pressure SHOULD be at 2.5 volumes, but you read 2.3 volumes after carbing, then shoot for the 2.7 head pressure next time and you should fall closer to 2.5. With trial and error and good record keeping you could do the no-vent carb and hit your targets fairly consistently. For what I've experienced as a production brewer of six years in high-volume breweries, carbing for most of a day or more is not practical or possible. Sometimes you have to get a beer carbed and racked in 2 hours to fulfill orders.


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What's your method for carbing a "high-volume" amount of beer in 2 hours consistently?

[BrewinLou]

Carb while you filter with a pin point carbonator. You can build a DIY version pretty cheaply.

[Meheen]

Carbonation methods

Check out this seminar from last years CBC on the subject. https://www.youtube.com/watch?v=DRXwLchVFG4 May help answer some questions.

Dave

https://www.meheen.com

[Matt Dog]

Thanks Dave!

[d_striker]

Check out this seminar from last years CBC on the subject. https://www.youtube.com/watch?v=DRXwLchVFG4 May help answer some questions.

Dave
www.meheen.com

Wow, thanks for sharing that. It's great info for those of us who couldn't make it to CBC.