Author Topic: Fermenting under pressure.  (Read 6523 times)

Offline tschmidlin

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Re: Fermenting under pressure.
« Reply #15 on: May 23, 2012, 01:30:55 AM »
Related to this, can someone remind me what the thing is called that you put on a corny gas out valve to regulate the pressure inside? Setting it to 15 PSI and then it vents when it goes over, until it goes back down to 15?
You mean a pressure relief valve?
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Offline phillamb168

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Re: Fermenting under pressure.
« Reply #16 on: May 23, 2012, 01:45:58 AM »
Related to this, can someone remind me what the thing is called that you put on a corny gas out valve to regulate the pressure inside? Setting it to 15 PSI and then it vents when it goes over, until it goes back down to 15?
You mean a pressure relief valve?

Yeah, but the one I'm thinking of has a regulator built-in so you can adjust the pressure at which it vents automatically.
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Offline tschmidlin

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Re: Fermenting under pressure.
« Reply #17 on: May 23, 2012, 01:51:09 AM »
Related to this, can someone remind me what the thing is called that you put on a corny gas out valve to regulate the pressure inside? Setting it to 15 PSI and then it vents when it goes over, until it goes back down to 15?
You mean a pressure relief valve?

Yeah, but the one I'm thinking of has a regulator built-in so you can adjust the pressure at which it vents automatically.
That is called an adjustable pressure relief valve ;)

morebeer has them, some with gauges.  You don't adjust with the gauge, that just tells you what you've adjusted it to.  So I'd pressurize to 20 psi, then adjust the prv down until the gauge reads 15 psi.

http://morebeer.com/view_product/16772//Ball_Lock_QD_Adjustable_Pressure_Valve_W_Gauge
http://morebeer.com/view_product/16771//Adjustable_Pressure_Relief_Valve
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Offline stlaleman

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Re: Fermenting under pressure.
« Reply #18 on: May 23, 2012, 02:29:35 AM »
The Brewhemoth sells one  http://brewhemoth.com/spunding-valve   it works quite well.

Offline tomsawyer

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Re: Fermenting under pressure.
« Reply #19 on: May 23, 2012, 05:33:50 AM »
Its called a spunding valve.  The adjustable pressure relief device is spring-loaded, and you can screw down to increase the pressure it takes to release.

I have a relief valve from McMaster Carr, its plastic but does a good job and goes to 30psi.  I also have the one they used on the Brewhemoth spunding valve attachment, it comes from Grainger.  Its brass, has markings that approximate the pressure setting, runs all the way to 100psi, and was a little cheaper.
Lennie
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Offline jmcamerlengo

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Re: Fermenting under pressure.
« Reply #20 on: May 23, 2012, 06:44:14 AM »
good info in here! Can always learn new stuff. I may try this in a small batch of a Scottish Ale. I think that would be a great test beer for this. You want it very clean, yet generally have to ferment around 60 degrees to achieve that, and it takes a bit longer than usual to get to terminal gravity at those temps. So this would be a good test batch.
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Offline MDixon

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Re: Fermenting under pressure.
« Reply #21 on: May 24, 2012, 05:05:47 AM »
Long ago I did some experiments with fermenting under pressure. I haven't updated my site in forever and most of my links are broken. First off high pressure may be dangerous depending upon how the container is rated. I seem to recall 45 psi was the pressure Doric yeast reached before it stopped fermenting and then once the pressure was released fermentation started again. I was not trying to see if esters were reduced or any of that jazz.

I found the linky
http://carboyclub.com/recipes/experimental1.htm
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Offline tomsawyer

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Re: Fermenting under pressure.
« Reply #22 on: May 24, 2012, 07:23:11 AM »
I agree about pressure being potentially dangerous, thats why I like a fermentor that has a pressure relief valve in addition to the adjustable spunding valve.

I think Chris White has indicated that yeast health is negatively affected above 15psi, interesting that they can still go up to 45psi.  I hope you lowered the pressure slowly, I'd hate to see yeasties get the bends.  Plus the beer foams up to beat the band if you just release the pressure all at once.
Lennie
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Offline jimrod

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Re: Fermenting under pressure.
« Reply #23 on: May 24, 2012, 11:47:13 PM »
So what is the verdict? Is it worth it to ferment under pressure? Lagers or Ale? What is the optimum pressure for what yeast?
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Offline phillamb168

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Re: Fermenting under pressure.
« Reply #24 on: May 25, 2012, 01:20:22 AM »
So what is the verdict? Is it worth it to ferment under pressure? Lagers or Ale? What is the optimum pressure for what yeast?

Personally it sounds to me like I'll buy buying a spunding valve set to 15 PSI and doing everything that way from now on.

Keeps the krausen down, meaning less cleanup, and I can do it in cornies, which means oxygen-free transfer AND free rhienheitsgebot-safe carbonation!
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Offline tomsawyer

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Re: Fermenting under pressure.
« Reply #25 on: May 25, 2012, 06:30:54 AM »
The technique has been applied more for lagers than ales but it works for both.  Supposedly 7psi is typical of the pressures in a large fermentor anyway, and 15psi is the limit above which yeast health starts to suffer.  Not sure that means the yeast start producing bad stuff though.

The lowered krausen is really a non-issue, you still have to have some head space above your wort to avoid blowoff and blowoff into your spunding valve does cause clogs.  I haven't really seen a significantly faster fermentation rate, it may get done a little faster but the yeast still have to drop clear and that time isn't accelerated by pressure.  The free carbonation is a slight benefit over what you get with conventional ferms, I haven't been dialing the pressure up to 30psi to take full advantage.  With an ale its tricky to time this, with a lager    The O2-free environment/transfers are probably a bigger benefit than anything else.  Thats what attracted me.  I've been troubleshooting my malt-forward beers that don't seem to have quite the flavor they could, and I hypothesized that oxidation was a culprit (after getting my water chemistry in order).  I still haven't concluded anything for sure (have to keep hoppy brews in the rotation) but I've made a few pretty tasty malty beers now so I've been sticking with it.  All in all, I am not seeing a huge difference but its no more difficult so I am doing it on the conical just to allow me to live with slightly higher ferm temps.

All in all its an interesting technique to play with but it doesn't seem to be head and shoulders above conventional methods.
Lennie
Hannibal, MO