Purging Dry Keg w/Fermentation Gas

[Berube05734]

Hi,

So, I'm having issues with residual Starsan (approx. 16oz) in my purged keg now that I'm using a floating dip tube. I never had this issue when I transferred the beer via the the liquid-in dip tube - I was able to purge virtually all but a tablespoon or so of the Starsan from the keg.

I want to continue using the floating dip tube, but I don't want to be consuming Starsan in every glass of beer.

My question is - will pushing the fermentation gas into an empty (sanitized and emptied) keg be as effective? I understand that O2 and CO2 mix, but if fermentation typically takes days, wouldn't days of fermentation gas pushed over into the keg eventually move all O2 out?

Side note - First time using Imperial Juice (A38) in a NEIPA and I was completely blown away. I've never brewed anything so...well, juicy / peachy tasting before. This yeast produced a beer that I've only dreamed about a beer tasting like.

Thanks,

Pam

 

[RogerGrahl]

Hi,

So, I'm having issues with residual Starsan (approx. 16oz) in my purged keg now that I'm using a floating dip tube. I never had this issue when I transferred the beer via the the liquid-in dip tube - I was able to purge virtually all but a tablespoon or so of the Starsan from the keg.

I want to continue using the floating dip tube, but I don't want to be consuming Starsan in every glass of beer.

My question is - will pushing the fermentation gas into an empty (sanitized and emptied) keg be as effective? I understand that O2 and CO2 mix, but if fermentation typically takes days, wouldn't days of fermentation gas pushed over into the keg eventually move all O2 out?

Side note - First time using Imperial Juice (A38) in a NEIPA and I was completely blown away. I've never brewed anything so...well, juicy / peachy tasting before. This yeast produced a beer that I've only dreamed about a beer tasting like.

Thanks,

Pam

Hi,

So, I'm having issues with residual Starsan (approx. 16oz) in my purged keg now that I'm using a floating dip tube. I never had this issue when I transferred the beer via the the liquid-in dip tube - I was able to purge virtually all but a tablespoon or so of the Starsan from the keg.

I want to continue using the floating dip tube, but I don't want to be consuming Starsan in every glass of beer.

My question is - will pushing the fermentation gas into an empty (sanitized and emptied) keg be as effective? I understand that O2 and CO2 mix, but if fermentation typically takes days, wouldn't days of fermentation gas pushed over into the keg eventually move all O2 out?

Side note - First time using Imperial Juice (A38) in a NEIPA and I was completely blown away. I've never brewed anything so...well, juicy / peachy tasting before. This yeast produced a beer that I've only dreamed about a beer tasting like.

Thanks,

Pam

I purge my kegs this way with no staling issues. But my beer doesn’t last long so this is totally unscientific. Somebody posted an analysis of residual oxygen using fermenter gas to purge the keg. Their math showed good results. I added a Spike All-In-One PRV to my fermenter, in addition to a regular 15 PSI PRV, before using fermenter gas. I don’t want an explosion. Thanks for the yeast tip. Brew on.

 

[Berube05734]

Thanks and yes, I read the oxygen analysis thread and, honestly, I was overwhelmed by the technical data / lingo and I wasn't sure if the analysis was isolated to purging liquid or an empty keg.

I did purchase a spunding valve. I do like the looks of the one you have...compared to yours, mine from More Beer looks pretty cheap.

All my kegs are 5 gallons, so I'll keg just 4.0 - 4.5 gallons in the fermenting keg. I'd like to do a hybridized version and combine the two...use the blow-off tube for the first couple of days and when the activity starts to calm down, remove the blow-off tube and attach the spunding valve.

The only issue that I can think of is if the gas-in post gets jammed up with thick krausen. I'd have two QDs - first one for the blow off tube and a new/clean one attached to the spunding valve. The only component not changed out would be the gas-in post. Do you have issues with a plugged post?

Thx,

Pam

 

[scrap iron]

Yes, you can use an empty sanitized keg. I have done this several times, but I use Iodine sanitizer to reduce oxygen starting out. One note is to make sure you have a good seal on the lid before you start. I did this once and afterwards found out my lid didn't seal.
As far as the sanitizer left in the keg, I do this. I cut the gas in tube short to be even with the inside keg surface. After pushing all the sanitizer out with co2 I leave a little pressure left in the keg. Then I spray the lid with star-san or soapy water to check for leaks. If it's ok then invert the keg and put a QD on the gas post over the sink and all the sanitizer sprays out. When done I have a sealed sanitized keg that I hook up the FV to the out of the keg and to the in to a jug with water.

 

[Berube05734]

I cut the gas in tube short to be even with the inside keg surface. After pushing all the sanitizer out with co2 I leave a little pressure left in the keg. Then I spray the lid with star-san or soapy water to check for leaks. If it's ok then invert the keg and put a QD on the gas post over the sink and all the sanitizer sprays out.

That's ingenious! I've been wracking my brain trying to figure out how to get that sanitizer out. Thanks!

 

[jerrylotto]

I generally put a quart of sanitizer in the kegs (three in a row) and push gas into the liquid out port so there is no blowback. There is a bubbler on the last keg in line gas in port. After fermentation, I disconnect the fermenter from the first keg and remove the last keg bubbler, then connect a sanitizer filled picnic tap to liquid out on the first keg. I hook up a C02 tank to gas in on that keg and blow all of the sanitizer through the picnic tap. Lastly, I introduce a priming sugar solution by filling a long gas tube with it and blowing it into the serving keg with C02 before filling with wort. That way, I can pull as many bottles as I want from the keg and let everything naturally carbonate. The next fermentation I do, I add a newly cleaned and sanitized keg (with a quart of sanitizer) to the end of the line and the second one becomes my next serving keg.

 

[AlexKay]

Another thing to consider is that if you're not getting all your StarSan out, there's a fair amount of oxygen dissolved in it. 16 oz. of solution dispersed into 5 gallons of beer will give you ~0.2 ppm of DO -- not the end of the world, but not the gloriously low levels people are usually shooting for when they use their fermentation gas to purge.

 

[BongoYodeler]

I can give my own anecdotal only evidence, nothing scientific. I typically clean and sanitize an empty keg and then purge it with only fermentation CO2 with tubing connecting my fermenter directly to my liquid out port on the keg, and a second line going from the gas in port to a jug of StarSan/water. I can't say whether or not this method completely removes all the O2 from the keg or not, but to date I have not noticed any perceivable oxidation doing it this way. And I typically take at least a couple months to finish a keg.

 

[Berube05734]

I can give my own anecdotal only evidence, nothing scientific. I typically clean and sanitize an empty keg and then purge it with only fermentation CO2 with tubing connecting my fermenter directly to my liquid out port on the keg, and a second line going from the gas in port to a jug of StarSan/water. I can't say whether or not this method completely removes all the O2 from the keg or not, but to date I have not noticed any perceivable oxidation doing it this way. And I typically take at least a couple months to finish a keg.

That's what I'd initially thought I'd do. I really like the floating dip tube, but it becomes problematic when trying to purge the last bit of starsan at the bottom of the keg.

Question - I am planning on hybridizing the keg fermentation process by using a blow off tube in the beginning and when krausen starts to subside, I'll remove the blow off tube and pop on the spunding valve. By not fermenting under pressure from the very beginning, I'm assuming that it will still be necessary to control temperature as if I was brewing in a carboy...?

As this will be my first time fermenting under pressure in a keg, I'm concerned about pressure / krausen going up into the spunding valve and I find myself in a mess in the middle of fermenting. So, I figure I'll get my feet wet with first using the blow off tube and and then switching to the spunding valve.

 

[jerrylotto]

Question - By not fermenting under pressure from the very beginning, I'm assuming that it will still be necessary to control temperature as if I was brewing in a carboy...?

Absolutely, and the optimal temp range for fermentation is independent of pressure. Just make sure youi have enough dissolved oxygen for a healthy growth (lag) phase.