Pressurized Fermentation Near Disaster

So I brewed a 10 gallon batch of APA on Sunday. All in all things went pretty well. This is my second batch of pressurized fermentation, and have been reading the thread on it which is awesome. Anyway

Day 1, Irish Red that I brewed was chugging along as expected but the pressure gauge still read 0

Day 2, Still read 0 in the morning which I though was really weird

This evening I went down it it was still at 0 so i started searching around and realized that I never put the sanke lever down and all the pressure was trapped inside the keg. I immediately put the lever down and the picnic tap turned into a foam fountain and had to pinch the line to make it stop.

Bottom line is that the gauge still read over 60 PSI after I let a lot of pressure out of it. At what point would this have become a bomb?

Also, it's going to be interesting to see if the beer turns out OK. Supposedly pressures over 14 PSI produce diacetyl and more green apple? If so this should turn out terrible. Also I may have killed all the yeast with the pressure drop. Anyway, could make for a very interesting experiment. If people are interested I'll update the thread with the results. I pull a sample that is very carbonated at the moment for a gravity reading.

You said this is a Sanke correct??? You better keep venting off that pressure... Supposedly the max recommended pressure on a Sankey is 60PSI...

I think you are going to definitely produce a ton of Diacetyl in this beer, but keep going full term with it... if you don't you'll never know... keep us updated for sure.

The outcome of this could be very interesting; I will be following this one.

aarondrich said:

Bottom line is that the gauge read over 60 PSI after I let a lot of pressure out of it.

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I'm just glad the valve didn't fail and launch the spear through your ceiling. High pressure is no joke!

At over 4 bar of top pressure and after such a rapid depressurization, consider it a learning experience. At this point, I would slowly lower the pressure over a few hours and see if the fermentation is still active. If not, pitch new yeast.

Edit: I added a warning to the pressurized fermentation thread.

I imagine that you are probably within 1.024-1.032 range... hopefully the rapid depressurization did not kill the yeast, but if it did try pitching in an active starter and cross your fingers...

i've often worried about this. as for forgetting to do stuff, i forgot to put the little ball back into the tap to prevent beer from flowing back into the fermenter. Not dangerous like your mistake, but important IMO to not contaminate your beer with beer that you've pumped out through the tap for samples/gravity readings. I guess ultimately this method involves more that can be overlooked.

Nice save, hope it turns out drinkable.

Yep, you have to release the pressure or you get a bomb! In my trials with this technique I let the pressure ramp up uncontrolled... once!!! After that, the only time I am not controlling pressure is when I want to carbonate. Always have the pressure venting from the get go! Glad you weren't hurt. I did talk about this in the thread, but I am sure accidents are gonna happen. In reality, the pressure would have been excepted into the beer and yeast would die before it exploded, but 60 psi is still really high for a Sanke. 60 psi was the head pressure, not the carbonated beer and head pressure. Still, you will probably have very untasty beer, but check it to see.

Wortmonger, do you have any idea as to what off flavors would be in the beer? Sounds like you did this once, what does untasty mean?

Why not use a calibrated pressure relief valve? My father in-law uses a 1.5 bar relief valve in his fermenter. However that fermenter is 150L.

That's affectively what I am using, I just didn't correctly hook it up

A typical Sanke will have a relief valve set at 60 psi. I'd expect the failure pressure would be 3-4 times that, but can't find an actual number. Since yeast can function up to 15 atmospheres, it could have exploded.

One of the guys I work with blew up a carboy once. It was in the stairwell of his apart building. The blast woke them out of a sound sleep and imbedded glass shards in the oak trim. I am guessing the fail pressure on a sanke would be considerably higher and that much more dangerous.

Well, one could always just toss a keg on a fire to discover its pressure limit.

aarondrich said:

Wortmonger, do you have any idea as to what off flavors would be in the beer? Sounds like you did this once, what does untasty mean?

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Yep, my maiden voyage I let it fire up to "over 30 psi" (gauge only went that high so I have no real numbers other than a greater than) and the beer had a slick mouth feel to it. Very buttery (such high diacetyl that it would never have been cleaned up. I thought it was my recipe for the longest time, but then realized after never screwing up another batch it had to be the higher initial pressure during the start of fermentation. I didn't remedy with additional yeast or any other possible fixes, so I can't comment on if it is really permanantly ruined. Live and learn, but don't give up. I have enjoyed many batches since then with 100% success. Oh and untasty is relative I guess. I mean, dogs like their asses and seem to love it but... I would think that was untasty, lol. Nah, it was just bad and undrinkable after the first glass.

david_42 said:

A typical Sanke will have a relief valve set at 60 psi. I'd expect the failure pressure would be 3-4 times that, but can't find an actual number. Since yeast can function up to 15 atmospheres, it could have exploded.

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Wow, I never would have expected the yeast to survive that high a pressurized environment. I learn something new everyday, and retract my earlier statements about it not being an issue. I'm so lucky I haven't taken my head off with a big boom! Thanks david.

I just checked the gravity of my beer that was jacked up to 60 PSI, and amazingly it fermented out to 1.010. So even after the sudden reduction in pressure to avoid blowing up the keg the yeast finished the job.

I'm the first to admit I don't have a very refined palate, but the beer doesn't taste bad? I was expecting a TON of diacetyl? If there wasn't any precursors could that be why?

We'll see how it turns out when it's carbed and on tap, but I am encouraged.

Could be, mine was an all pilsner first brew. So... maybe that was why for me. Glad to hear it finished nicely. I love P-fermenting!!!

You are the luckiest guy on Earth!! That could have ended disastrous. A gentle reminder to be careful while brewing.