Pressure Fermentation at last

I have been on a long journey toward a completely closed cold side in my brewery.  This is the last element.  A while back, I made the switch to fermenting in a 10 gallon corny, with the intention of doing pressure fermentation with an adjustable PRV (aka spunding  valve) I got from MoreBeer, but never quite got there.  (Just improvised a airlock in the interim.) Now I’m finally implementing  this,  and said in another thread I’d report.

Let me start by thanking ynotbrusum for the simple question that lit the fire under me to finally implement this,  and BrewBama for pointing me in the direction/ down the rabbit hole of the information I still needed to do so.

The PRV itself is a little janky, but I understand that it is intended to be a safety device and not a precision regulator, so that’s acceptable.  It will just take some ongoing fiddling to get it to hold somewhere  in the ballpark.  And it can’t be set terribly low, as the rising stem will be so far out on the threads that it’s unstable.  But it is perfectly adequate for the job, as far as I can tell so far.

Yesterday I brewed, pitched dry S-04 at 72°F, pressurized the fermenter,  set the PRV to 6 psig, and set the fermentation chamber temperature control to 60°F.

Overnight temperature dropped, and pressure dropped to just below 3 psig during the lag.  This can’t be accounted for just by cooling; obviously it was mainly gas going into solution, as in tests cooling an empty fermenter had minimal effect on pressure.  And it occurs to me that the gas going into solution will include oxygen, as the fermenter was just pressurized,  not purged.  Seems an  easy way to oxygenate wort.

At 24 hours from pitching, fermentation temperature is at the desired 64°F, and pressure had risen to 8 psig, so I’m fiddling with the PRV some more to try to get it to hold somewhere in the range of 5-6 psig.  Think I’m figuring it out.

At 48 hours I’ll take my first sample,  which will be a greatly simplified procedure now, as I won’t need to get a gas supply to the fermentation chamber.  I’ll report then how fermentation progress compares to past experience.

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FWIW, at ANHC Chris White said that their experiments had determined 1 bar was perfect

Thanks, Denny.  The thing that had me stumped all this time was not having a clue what pressure to use.  I’ve now read a bunch suggesting that anywhere up to 1 bar seems to have minimal effect on fermentation and flavor,  so I am not worried for that reason about precise control.  I just want to avoid significant carbonation to make transfer to keg easier.  But at ale temperatures or with a diacetyl rest, there’s not going to be more than around 0.5 v/v anywhere in that pressure range IIRC.

Chris had a great chart of pressures vs. yeast strain vs. temp, with results for each.  I’ll see if maybe I can get ahold of it.

It should be here somewhere, but I couldn’t find it so please feel free to look for yourself.  I’ve also written to the organizers to see what’s up.  And BTW, there’s a LOT of other great info in these presentations!

That’s the hardest part of homebrewing: the wait to see…

Here’s to a great beer!  Cheers! [emoji482]

I will soon be joining you.  I just pulled the trigger on a pair of these… seemed like a fermentation chamber that had most of what I was looking for… here’s to hoping they don’t suck!

Cool!

Have you had any trouble with clogged diptubes or poppets in the keg? Trying to get ahead of potential hiccups.

None.  If you’re worried about the gas side (obviously the critical element here,) I’d think 7.5 gallons should be plenty of headspace for a nominal 5 gallon batch, especially under pressure.  In my 10 gallon corny even unpressurized, just with my improvised airlock, there’s still only a few inches of kräusen with most yeasts. In fact I wish there was  a 7.5 gallon corny.  (I always start with between 6 and 6.5 gallons in the fermenter.)  Pressure, as I understand  it,  should further suppress the foam.  I’ll know better after this batch.  I see you have a floating dip tube in the Kegmenter.  I can’t predict how that will function floating in the kräusen,  but I have to assume they’ve addressed that.

BTW what PRV are you planning to use?  If it’s other than the off the shelf model from MoreBeer or Williams,  etc. I’d be interested in what you’ve put together.

I use valves from Brewhardware.com currently on my corny legs for spunding.  They’re great as long as you don’t hook em up to the liquid out post… not that I’d know… 
The fermenters do have a floating diptube, not sure how well they will work, so I ordered a couple more tried and true Clear Beer versions.  They will go in corny kegs if the others work fine. 
A friend at my club showed me these kegmenters after we met up for a couple pints to discuss brewing and I lamented that there were no 8 gallon kegs out there.  What drew my attention to these fermenters is that they were as close to a 7.5 or 8 gallon corny keg as I have seen (in functionality) while being cheaper than even an SS Brewbucket.  I just really couldn’t find a big downside… maybe width as I’m not sure they will fit in my small chest freezers, but I’ve been meaning to fix that situation anyway.

I have sometimes, not often.  When that happens I remove the poppers from both the keg and QD.


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Proving I shouldn’t post when I’m sick, here’s the link I forgot…https://www.anhc.com.au/presentations

Lots of good stuff, but Chris asked that his presentation not be published, so there’s no pressure fermentation info.  I’ll try to contact him and see if we can at least get his chart.

Thanks for the effort.

UPDATE
48 hours from pitching.  Took a sample expecting to see >50% ADF and pH dropped to around or just below 4.0.  In fact only at 31.7% ADF and pH only down to 4.46.  Temperature also still at 64°F whereas it would normally rise a degree or two higher at peak activity (which was apparently indicated by 7 psig and audible hissing this AM.) Initially it seems things are significantly slowed down under pressure.  Sample tastes good though.  Will sample again tomorrow morning.

Thanks for the update.  My fermenters won’t be here in time for a Best Bitter I’m brewing tomorrow, so back to the old glass carboy for me.
Interested in how long it takes you to reach FG and whether that differs from your expected FG.  Also, any tasting notes.

UPDATE
66 hours, 45.3% AA, pH 4.31.  Will sample again later today, still awaiting >50% AA, at which point SOP is to allow free temperature rise to 70°F controlled ambient.  Very slow, this batch.  But no signs of other abnormalities.  I can be patient as long as the result is good.

Interesting stuff, for sure.  I now have the 13.6 gallon kegmenter for my 10 gallon batches and an interesting pressure valve that Williams sells from Australia called the “BlowTie” which hooks up with simple push fit collets (like my RO system - tubing 8mm, IIRC).  I am sending this remotely, so I don’t have the links handy, but with a valve and some short tubing a couple fittings and a gauge, I prepped a system to try out pressure fermenting.  Lastly, BYO has a recent replication recipe for an Altbier that a brewery in Vermont ferments under pressure, with English ale yeast no less!  So, I might have to give that a try!  Gotta cut off the dip tube on the kegmenter about a half inch, which is my most fearful step…

The benefit of fermenting under pressure that I always hear about (and maybe read about in Yeast?) is that it suppresses esters, allowing you to ferment at a warmer temperature and finish more quickly than you would otherwise.

Is that what you’re after or are there other benefits?

My interest is in having a simple, completely closed system,  and the added benefit of a ready supply of CO2 for drawing samples.  I don’t really want to change the fermentation character,  though that will be something to explore in the future.  And yes, Chris and Jamil’s book says increased head pressure decreases esters and fusels.  But some xBmts may suggest this effect is negligible.

(I wanted to follow my SOP regarding temperature program, and everything else, this batch because, well one variable at a time, right?  Science.  Next batch I may run at a steady, higher temperature.  I’m also interested in the viability and/or adaptation of repitched yeast from pressure  fermentation.  Much to learn.)