quick check - proposed pressurized fermentation process?

[aangel]

I'm looking to speed up my process by using pressurized fermentation. Can someone look at my proposed method and tell me if it'll work?

Here's what I'm envisioning:

-ferment in keg 1. keg 1 gas output jumped to keg 2 gas post. keg 2 is filled with starsan and its liquid post is connected to a bucket. this way i purge keg 2 and it's ready to use as my serving keg.
-once fermentation's half-way finished, (and keg 2 is empty of star-san), I connect keg 1's gas post to keg 2's liquid post, and connect keg 2's gas post to a spunding valve, set to 25psi (2.4 volumes of CO2 at 68F). The fermenting wort eventually pressurizes both kegs up to 24PSI and the beer becomes fully carbonated.
-I take samples using a picnic tap from the fermenting keg every few days to test gravity using a refractometer.
-Once the beer's reached terminal gravity, I disconnect and place both kegs into my kegerator.
-24 hours later, now that the beer is sufficiently cold, I open up keg 1's lid, sadly losing a bunch of CO2, drop the gelatin solution in, close the lid, use my CO2 tank to repressurize to (now) 10PSI at about 38F (2.4vol CO2).
-3 days later, the gelatin having done its thing, I connect the liquid out of keg 1 to the liquid out of keg 2, and connect the gas out of keg 2 to the spunding valve, and set the spunding valve to 8-ish psi. the beer (should) now flow from the fermenting keg into the serving keg, slowly, without losing carbonation, and be basically ready to drink immediately?

 

[Burquebrewer]

I've done a couple of batches so far fermenting under pressure. They both came out ok. The first was a quick and cheap test batch, which surprisingly tasted pretty good. The second was a leger I took a bit more time with. Here are a few pieces of advise I learned the hard way and wish I had before I started.

1) 25 PSI is too high. I'd stick with 14 PSI during the entire fermentation. Anything above 15 PSI is supposed to be bad for the yeasties.

2) I wouldn't open the fermenter to add anything after the first three days. If you want to use fining agents, use those that can be added during the boil (Whirlfloc or Irish Moss). The reason is that a rapid change of pressure can kill the yeast (basically giving them the bends) Also, like you said, you lose the CO2.

I keep the pressure set to 14PSI during fermentation, let the beer ferment out almost to completion in keg 1, transfer to keg 2 when there are 4 or 5 gravity points left to go by removing the spundling valve from the gas out on keg 1, resetting it to 11 PSI and attaching it to keg 2 gas out post to avoid a drastic change in pressure. The beer transfers slowly from keg 1 to keg 2 by a jumper from liquid to liquid, then I keep the spindling valve set at 12 PSI and keep it on Keg 2. 12PSi at 40 F should get you right around 2.5 volumes of CO2.

Another option is to let the wort fully ferment in keg 1, add a liter or so of unfermented wort to keg 2, purge any oxygen, then transfer the fermented wort to keg 2 as described above. This method of krausening for carbonation worked nicely for me when I made my lager, as the spindling valve keeps it at 12 PSI, so exact measurement of unfermented wort is not a big concern.

 

[aangel]

Ok there's something weird going on for me then. My partial pressures expertise isn't great.

Brewer's Friend has a keg carbonation calculator which suggests that, for 2.3 volumes of CO2 at 68F, I need 24.5PSI. At 40F, that becomes 10.1PSI to maintain the 2.3 volumes of CO2.

I interpreted this to mean that, if my fermentation finishes at 24.5PSI at 68F, if I throw that keg into my kegerator, by the time it settles to 40F, the pressure will be 10.1PSI.

Making use of gelatin at transfer time is fine - I'm only doing so when the yeast are done, and about to be discarded. I don't repitch onto the yeast cake.

 

[Burquebrewer]

I'm fairly new to this as well, just sharing what I've read here and picked up from my own experiences. Its worked good for me. Maybe someone with more experience can chime in?

 

[NZhomebrew]

Hi I have had no issues with fermenting at up to 28psi.

 

[crane]

I've been fermenting under pressure for a few years now. I would skip the gelatin. Yeast will drop out quickly after a cold crash. I start at 3-5 psi until peak fermentation is over then start ramping up pressure over the next couple of days. Usually ending up around 20-25 psi. I've seen no I'll effects by going above 15psi towards the end of fermentation.

Make sure to add ferm cap if you are going to be doing a 5ish gallon batch in a 5 gallon keg. You may still find that you have blow off into the second keg. Shouldn't be a problem if you aren't trying to reuse your sanitizer.

 

[Brendos]

Hi guys I started fermenting under pressure four months a go using a special lay designed keg. In theory you can go from pitching to drinking in 7 days. I usually squeeze it out another 3 as don't ferment at as high temperatures as suggested. Here's the Manual for it. https://williamswarn.com/wp-content/uploads/2017/03/BrewKeg10-User-Manual-Web-v5.pdf

Fermenting pressure builds up to 22psi within a day or two and is held here for the whole process - defiantly no problem with this.

 

[max9]

What fortuitous timing for this thread. I'm about to try my first fermentation under pressure and was wondering about blow-off to plan for headspace in my fermentation vessels. I avoid foam control products, but I would imagine the pressure would keep foaming down somewhat. I'm using WLP925 yeast which recommends fermenting at 62-68 F and about 15 psi. Anybody have any experience?

 

[Brendos]

My set-up recommends using a space of about 6cm/2.36 inch.

 

[max9]

Thank you!

 

[arrasmithf]

I'm using WLP925 yeast which recommends fermenting at 62-68 F and about 15 psi. Anybody have any experience?

I am looking to do this as well. I searched the White Labs website and found this yeast in their yeast vault. They need 250 orders in order for them to produce and ship yeast from the Vault. Did you also pre-order from the Vault, or get from somewhere else? If you ordered from the vault, how long did it take for you to get your yeast?

 

[max9]

I am looking to do this as well. I searched the White Labs website and found this yeast in their yeast vault. They need 250 orders in order for them to produce and ship yeast from the Vault. Did you also pre-order from the Vault, or get from somewhere else? If you ordered from the vault, how long did it take for you to get your yeast?

 

[max9]

Yup, I ordered it through White Labs yeast vault. It took quite a while to get it though... Something like four months. I was pretty happy with the yeast, so I would say it was worth it.