Reusing CO2 from FV

[scott isham]

When I transfer beer from the Fermenter to the serving tank I use CO2 and don't use a pump. When the fermenter is empty I have a tank full of CO2 at 15psi. It seems like such as waste just to vent that much CO2 to the atmosphere. I was wondering if I could at least reuse some of the CO2 to top off the head pressure of another fermenter that's going to be transfered soon. I don't think anything can survive in CO2, so I don't think I would be introducing any bugs or anything. Maybe a few flakes of dried up krausen might get through, but I could use a filter of some sort to catch those. Is this a good idea or am I missing something?

[NYSBrewer]

If, by chance, there was any oxygen in your serving tank, that would end up in your fermenter after the rack was compleat. Pushing that onto another beer may be enough to oxidize it, that is my only concern, and why I dont reuse. I would'nt mind hearing some other opinions....

[WitsEnd]

If you're using CO2 to push from the FV to the serving vessel, how would oxygen from the serving vessel get into the FV?

You're right, there's a great deal of potential energy left in a full FV at 15 PSI.

I would think you could use this to at least partially push the next FV into a serving tank until the head pressure drops to the point that you're not getting the flow that you need.

Another option might be to use it for purging a recieving tank. Instead of venting to atomosphere, sent it through a serving vessel before venting, reducing the amount of oxygen in the tank.

[jwalts]

If your water doesn't have enough alkalinity (yeah right), you may be able to bubble the leftover CO2 through your next batch of brewing water to help dissolve calcium carbonate. I have no idea how much CO2 or time that would take, though.

Joe

[NYSBrewer]

When racking from an FV to a serving tank, there should be a hose from the top pf the serving tank, connected to the side-arm if the FV to equalize pressure. As the beer moves into the serving tank the gas that is in the tank gets displaced by the beer and ends up back in the FV. If your serving tank was not compleatly purged of all oxygen, it will end ub in the FV when it is empty. It may not be enough to oxidize a beer, or if you are certain that the serving tank is compleatly purged with co2, then there would be no oxygen.

[South County]

Final CO2 purge/fill on keg cleaning runs? Obviously the pressure will diminish as you fill the kegs but I would think you could offset some of the CO2 needed. By using the gas to purge smaller containers I would think you would have less O2 pickup.

[GlacierBrewing]

When I'm filtering, I pressurize both FV and BBV to about 13psi and equalize them. When I'm done with the filter, my BBV is now full of filtered beer and pressurized for carbonating. I then distribute the CO2 in the FV to any other tank that may need it (BBVs for carbonating, BBVs for racking, FVs for next filter, etc). Follow quality brewhouse/cellar sanitation practices AND make certain your gas transfer hose is sanied! I've been doing this for quite a while now with no problems (knock on stainless!).
Dave

[kramling]

Are you guys purging the serving vessel/BBT of Oxygen prior to transfer from FV? What is the likelihood of oxidation in a finished product from not doing this?

[NYSBrewer]

Yes, purge, purge, purge!!!

[GlacierBrewing]

Yes, always purge the tank. Why give your new beer any more unnecessary contact with the atmospheric gas mix? I worked at a micro where the cellar guy was of the opinion that all he needed was a "blanket" of CO2 on the bottom of the tank and as the beer was CAREFULLY and CALMLY introduced into said tank, the column of liquid, topped by CO2 would push out all the ambient air. For what it's worth......

Prost!
Dave

[WitsEnd]

When racking from an FV to a serving tank, there should be a hose from the top pf the serving tank, connected to the side-arm if the FV to equalize pressure.

The OP stated that he moved the beer with pressure and no pump. I don't think this would be possible with an equalizing hose.

[Kushal]

co2 is neat

You can push the co2 through an inline filter if you are worried about contamination. And if you are worried about air in the tank, let it sit over night and then move the co2 from the bottom, as it is heavier than air.

[NYSBrewer]

Right, Witsend, my bad.....

[jwalts]

Hey Kushal, I'm pretty sure diffusion trumps gravity in terms of gas mixing. The CO2 blanket works to your advantage (though not completely) when purging a tank from the bottom, but I think the CO2 and air would be pretty evenly mixed after an overnight rest.

[gitchegumee]

Purging is about the only thing you can do with fermentation gas. It cannot be used to carbonate as it must be scrubbed clean first or it will give headaches. And I'm with jwalts on diffusion trumping gravity. Leaving the two gases together overnight will just cause them to mix more--regardless of density. Fill your tank with water and push with CO2 for an effective purge.