Pressure fermentation and TILT

[RickyBeers]

So beyond my nightmare of wild fluctuations in pressure of my spunding valve and krausen blowouts through that same valve all over the floor... I also have Tilt issues. Hard drops in the first 24 hours for my gravity, but then a stall, as shown below. So I gave it a good shake and repositioned in a slightly hotter area of the basement. Using Omega Lutra yeast so when I got down to 69f I realized I was a point away from being at the lowest temp for this yeast. Might move it to the garage to get it up to mid 80s depending on how the next day goes... Anyway, below is data, and graph (comical). The sharp drop is after I let it settle from shaking the corny keg and repositioning. Did that the night before and took reading in morning. Any thoughts on if this could be real reading?

Timepoint	SG	Temp (°F)
7/1/2021 6:41:45	1.006	71.0
7/1/2021 5:18:05	1.006	71.0
7/1/2021 4:49:39	1.007	71.0
6/30/2021 20:59:25	1.027	70.0
6/30/2021 18:47:36	1.027	70.0
6/30/2021 17:25:22	1.027	70.0
6/30/2021 16:21:49	1.028	69.0
6/30/2021 14:44:22	1.026	70.0
6/30/2021 6:11:43	1.028	70.0
6/29/2021 22:36:35	1.029	70.0
6/29/2021 20:55:38	1.029	70.0
6/29/2021 19:32:12	1.026	70.0
6/29/2021 19:11:17	1.027	70.0
6/29/2021 18:01:28	1.030	70.0
6/29/2021 17:11:16	1.030	70.0
6/29/2021 9:09:10	1.030	71.0
6/29/2021 8:23:52	1.030	71.0
6/29/2021 7:51:10	1.029	71.0
6/28/2021 23:08:29	1.032	72.0
6/28/2021 22:05:06	1.032	72.0
6/28/2021 20:13:51	1.032	73.0
6/28/2021 18:55:25	1.033	73.0
6/28/2021 17:25:40	1.034	74.0
6/28/2021 16:26:30	1.033	74.0
6/28/2021 15:01:05	1.033	74.0
6/28/2021 12:00:45	1.033	76.0
6/28/2021 10:33:22	1.034	77.0
6/28/2021 7:44:53	1.035	78.0
6/28/2021 6:41:19	1.034	79.0
6/27/2021 23:16:48	1.040	84.0
6/27/2021 19:17:37	1.048	87.0
6/27/2021 17:58:40	1.048	89.0
6/27/2021 17:28:15	1.048	90.0
6/27/2021 17:11:18	1.049	91.0
6/27/2021 15:44:02	1.048	93.0
6/27/2021 15:23:34	1.048	93.0
6/27/2021 14:52:21	1.050	79.0

 

[micraftbeer]

At what date/time did you get krausen blowout through your spunding? At times of high krausen is when you'll have stuff stick to Tilt and start to throw off readings.

Also, what pressure is your spunding reading at for your data points at 6/30 and 7/1? If you're at bottom of recommended temperature range and a very high pressure, you might be asking too much of your yeast.

 

[RickyBeers]

Good questions.
Krause blowout came around 10pm the first night so within 8 hours of pitching yeast. I spent 3-4 hours adjusting spunding valve because pressure was all over the place, sometimes ramping up to 25 psi but I always caught that quickly. I had read that max should be 15psi so I started with the goal of keeping it at 10 psi the entire time. It would sometimes drop to 5 psi, back up over 15, etc. finally got it to stabilize a bit. So to sort of answer your question, I’ve attempted to keep 10 psi but it did move around a lot.

The next morning around 9am it began to blowout again,less craziness with pressure fluctuation but still some. Once the second blowout happened everything appeared to settle down and that’s when gravity readings stopped moving much. Most of the middle of graph.
I’ve been able to hear co2 escaping the spunding valve the entire time, that hasn’t changed.

when I shook the tank and moved it, it’s now up to 72 degrees and pressure is at 12psi. Still don’t understand the point of the spunding valve if pressure doesn’t hold, but that’s not the main part of my post so I’ll drop that…

My app had said my recipe could yield a 5.7% beer, it’s saying 5.78% with tilt now, but that’s only about 4 days and I’ve yet to have a brew that is OVER the abv that the recipe says, not to mention the gravity started well under, and now it says the gravity is well under what it had projected. Could be a calibration issue I suppose, but my initial spring water reading was 1.000

 

[micraftbeer]

Here are my thoughts:

1. I haven't brewed with this yeast (or any Kveik), but I have heard they are fast fermenters. So your overall timeframe to finish fermentation in ~3.5 days sounds legit. Yeast under pressure ferment somewhat slower, but if you're keeping it around 10 psi, it might not be too long.

2. With a lot of krausen, it can stick to the top of the Tilt, dry, and then mess up the angle it sits at, making the gravity readings less accurate for absolute value. So your actual gravity might be lower or higher than 1.006 its showing now. With you having two yeast blowouts in your spunding, you definitely check the box for "a lot of krausen". So I would be shocked if your current reading value is very accurate right now.

3. The chemical reaction of yeast converting sugar to alcohol makes CO2 as a byproduct. So if your spunding is off-gassing, your yeast are still working, adding CO2 into your headspace. So regardless of your Tilt reading, if you're still getting gas out of your spunding, just let things keep going.

4. The point of the spunding is to control the MAXIMUM pressure in your headspace. At start of fermentation, your headspace isn't all jammed up with CO2 molecules, so the pressure is low, and your spunding doesn't off-gas anything. As fermentation continues and more CO2 is made and goes into the headspace, it starts to get crowded and pressure starts to rise. Once the pressure gets to the level of your spunding, it starts operating like a bouncer at a night club- the amount of CO2 into the headspace matches the amount of CO2 released. If you want your headspace nightclub to hold more guests, you crank up the pressure setting. However, you will reach the mechanical limits of your fermentor at some point and you have to relieve some amount of pressure so it doesn't burst/split/balloon. Plus, there are limited studies out there on homebrew pressure fermentation, but they do seem to indicate 10-15 psi spunding is better than 28 psi. So you do want it to be constantly bleeding off CO2, in order to not over-pressurize things.

 

[RickyBeers]

First of all, I’m very grateful for your responses. I love brewing but the ambiguity is sometimes maddening, yet also what makes it so alluring.
1. Good point, it’s an intense yeast, time frame does make sense.
2. I agree. I think I’ll need to take a FG reading the old school way to ever truly know. I trust my initial gravity but that’s about it. Bummer first experience with Tilt but I don’t blame the sensor.
3. good to know, that’s comforting. I’ll keep listening and waiting.
4.I think I understand better now. I thought that if I set the spunding valve to 10 psi on another tank that it would be set to go no higher than that regardless of the tank I put it on after. That’s why I got spooked when it wasn’t holding at 10psi, or at least close. I also thought the point of pressure fermented was to have less head space, then I got the blow out, so I figured my spunding was faulty because of all of that.
Anyway, thank you again, cheers

 

[micraftbeer]

Cool. Some more thoughts based on this.

2. Think of the Tilt as a "fermentation progress gauge" instead of a "real time hydrometer". It works great to let you know when fermentation starts, whether it's progressing fast or slow (usually), and when it's finished fermenting. The FG VALUE it reports when you reach final gravity needs to be independently measured when you transfer to keg, but it definitely goes flatline once the gravity stops changing.

4. I see your question. Generally, yes, 10 psi should be 10 psi anywhere, I guess depending on the spunding design. You have to overcome a spring force to open a pathway to bleed off pressure. That spring is the same everywhere. Differences could come in I imagine that maybe there's a factor with flow rate in there, depending on the design. And maybe a vigorous fermentation that's pushing out a lot of gas, you might get a different regulation pressure than something else that's not pushing out a lot of gas. And, regardless of design, once you get krausen in there, it's going to cause friction in there, and that will make its performance worse (higher pressure to open, lower pressure to close back down again). Your assumption of less krausen and less likely for blowout while fermenting under pressure I agree is sound, and has been my <limited> experience. Maybe with kviek yeast, you need to start off with some CO2 in the headspace from the start to try to avoid that first blowout.

 

[z-bob]

What pressure are the seals in the TILT rated for? I would be afraid to use it in a pressurized system; beer might leak inside and ruin the electronics. Although 10 psi doesn't sound like all that much so maybe it's okay.

 

[micraftbeer]

I've fermented a few beers (6) with Tilt at 15 psi, and haven't had issues. I've had these Tilts for several years and never changed the seals, so they weren't fresh or new or anything. So there's that.

I looked at Tilt website to see what they said, and their FAQ simply said "yes they can be used in ferment under pressure, read this blog post by us." And the blog post mentioned fermenting at 15 psi. Not overwhelming evidence to be sure, but hopefully they wouldn't write and post something on their website for a practice that would damage their product.

https://tilthydrometer.com/blogs/news/controlling-fermentation-rate-with-pressure