CO2 purging with dry ice

[shua5150]

So, I am getting ready to rack into my secondary fermenter when it dawned on me, could you purge the air from a carboy with dry ice.

I used the ideal gas law PV=nRT (hello high school chemistry) to calculate that I would need 1.23032 oz or 34.87901 g of dry ice to fill my five gallon carboy with co2. ( I live at sea level and my house stays at a pretty constant 64, you can check my math)

I am more curious about people's thoughts like "you're wasting time/money" or "absolutely!"

I do the keg, and don't plan to any time soon so this is just an idea I am entertaining to limit oxidation.

What's your thoughts?

 

[jeffpn]

Interesting idea. I'd think aside from the potential risk of cracking the carboy from the rapid temperature change, it's a fine idea. I read from a lot of people who purge their vessels with CO2 before filling them. Maybe I'll try it one day.

 

[shua5150]

I did consider the damage. My carboys are both plastic so I may be OK. Glass would be a different story maybe. 1 oz isn't all that much I would figure you could have the carboy sitting in a warm water bath seeing as both plastic and glass are more conductive and not great insulators (correct me if I am wrong) the water would help dissipate the temp changes while the dry ice sublimated.

 

[Starter Hops]

Speedy Eisbock?

 

[Ozarks Mountain Brewery]

kind of expencive

 

[shua5150]

$2.99/lb so price isn't terrible

 

[J A]

$2.99/lb so price isn't terrible

You have to buy a whole package of it - certainly not less than a pound - every time you want to purge a vessel. You'd end up using maybe an ounce or so to purge and the rest would go to waste.
If you wanted to be industrious, you could make a simple CO2 generator with a 2 liter bottle, tubing, big plastic bag and baking soda and vinegar.
Lot of trouble to go to either way to solve a problem that may not exist. if you're transferring to secondary while fermentation is still slightly active, there's CO2 in suspension and it pushes oxygen out of the vessel as it's filled.
Keeping oxidation to a minimum is important, but at the level that you're likely to encounter it using reasonable care, you'd probably never notice it in most beers. If you're making something that requires aging, it might make sense to go to some extra lengths.

 

[GFHomebrew]

Yea I don't purge my keg before filling but I don't see why once full you can't purge out the oxygen then by burping filling burping ect. The beer will push the oxygen out the keg as its filling then you just need to purge that tiny head space at the top.?

 

[Mark D Pirate]

Oxygen will dissolve in the beer in seconds Ben , if you turn kegs around quickly you'll never notice the difference .

OP could get around the oxidisation during transfer by simply skipping the transfer to secondary , single vessel only for me now except bottling day and then the dissolved CO2 forms a blanket for me

 

[J A]

except bottling day and then the dissolved CO2 forms a blanket for me

So no purging of the bottling bucket? If dissolved CO2 is sufficient for all the time a beer is sitting around in the bottling bucket, why isn't it enough to produce a blanket above the rising level of liquid in the keg as it 's released. Purge or no purge, I don't think there'd be any oxygen left in the headspace after filling. Easy to check is hold a lit match over the open lid and lower it past the lip and into the headspace. It'll probably be extinguished.

Purging bottles and buckets is a little bit of a chore, but easy enough with kegs...just put the lid on. pressure up, release purge valve, repeat.

 

[jeffpn]

I believe that the key is to siphon quietly. In my opinion, anything more just gives you something to talk about. Anyone want to hear me talk about doing a secondary for all of my batches?

 

[Mark D Pirate]

A small amount of oxygen will make its way into my bottling bucket , I get a small secondary fermentation in the bottle which will scavenge the miniscule levels of oxygen anyway .

Beer only sits in bottling bucket for an hour maximum , the small rise in temp will vent a little CO2 anyway as additional protection .

 

[shua5150]

I do see and understand the idea that it seems excessive for the cost and miniscule amount needed.

I plan to put a batch in secondary for 14 days, hence the idea of removing the co2.

 

[Nosybear]

You don't need a whole lot of CO2 to prevent oxidation - dry ice seems an interesting idea but a bit of overkill. I bought a tank and regulator - still more pricey since I don't keg - but it's pretty much killed off oxidation in my beers. I purge the carboy if I rack, the bottling bucket and have no problems.