Pressurized fermentation.

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That's a good point!

I don't believe that most of our pressure gauges read very well at low pressures. I do believe that all the batches I've tried have started building pressure immediately after pitching an active starter.

Thanks for posting all the other info about your process Dent. Good stuff.
 
Regarding ester formation and brewing under pressure don't forget to read the papers in the links from posts 21 and 22. They're very clear about the relationship between ester formation and yeast growth under pressure. Thanks wobbly and beerisyummy for those great links!
 
Seems that pressure has no impact on fusel production so the increase in temp also means an increase in total fusels.
Sounds like headache material but I'd be interested in hearing if any of you guys had noticed this.
 
I haven't noticed any. Not saying it can't happen though - I only run the temperature up to 14 degrees for lager yeast, and 20 for ales. I have done a few 9% beers under pressure and they were very smooth/drinkable alcohol wise - it is pretty obvious when the big beers start getting unpleasantly boozy.
 
wobbly said:
For those experiencing issues with sourcing a functioning "spunding valve" these details of a "home made unit" may be of some assistance http://www.homebrewtalk.com/f51/spunding-valve-commericial-style-diy-333907/

Cheers

Wobbly
Nice link Wobbly. I can't believe I missed that one in my searches.

Tomorrow I'll try to get another test batch on in the keg fermenter. This time I'll take some photos of my garden tap spunding valve.
The next batch is going to be a kit beer, just to see if they still taste like crap. :ph34r:
 
El cheapo PRV at work

IMG_0428.JPG
 
Thinking of doing something similar, though in a corny keg. Does the pressure reduce the size of the krausen, and therefore the head space needed?
 
Rambo said:
Thinking of doing something similar, though in a corny keg. Does the pressure reduce the size of the krausen, and therefore the head space needed?
It appears so Rambo - I am up to my 3rd pressurised brew and the Krausen appears to be less. I am doing a 1.076 IPA at the moment and from what I can see its not trying to climb out of the fermenter - yet.

I haven't read all of this thread - but all I would say is that I wouldn't be relying on a spunding valve for all of the pressure relief. I would have thought it imperative to have a separate control and pressure relief valve.

RM
 
Why do you think you would require a seperate PRV to the spunding valve, surely theres not that much pressure to relieve?
 
From what I've read around the traps, the pressures can get pretty high. 60+psi.

It can't hurt to have a backup.
 
I avoid going over 40L in a 50L keg. Getting krausen in your PRV is pretty annoying - it also will dry up, get sticky, and completely upset the calibration - it can even seal itself shut which is bad for obvious reasons.
 
From the reading I have done - the amount of CO2 produced during a normal ferment is 10+ times the amount needed for carbonation.

Thats a high volume of gas to get rid of. I know I could easily exceed 3 Bar in my fermenter - that has a 3 bar PRV as a safety.

I work in an industry where putting eggs in one basket is considered a no no. Most pressured tanks have 3 safety devices - 2 PRV's and a bursting disk. I would consider putting all faith in a spunding valve - that could pretty easily get clogged with krausen (if the vessel wasn't big enough for instance) is risky


Thats all


RM
 
Gryphon Brewing said:
If at all worried about krausen the just add some anti foam , used in the right proportions it will not affect the brew negatively.
Nev
Nev - no downstream effect on head retention?

RM
 
roger mellie said:
From the reading I have done - the amount of CO2 produced during a normal ferment is 10+ times the amount needed for carbonation.

Thats a high volume of gas to get rid of. I know I could easily exceed 3 Bar in my fermenter - that has a 3 bar PRV as a safety.

I work in an industry where putting eggs in one basket is considered a no no. Most pressured tanks have 3 safety devices - 2 PRV's and a bursting disk. I would consider putting all faith in a spunding valve - that could pretty easily get clogged with krausen (if the vessel wasn't big enough for instance) is risky


Thats all


RM
Hey RM,
From the reading I've been doing, the yeast will cease to make CO2 beyond a certain point. From memory, the figure is around the 35psi mark.
My personal experience is that it's not that hard to get 35 psi (2.4bar) at room temp. Beyond that, I'd imagine you'd have to tweak the temperature and other variables.

Of course, none of this takes into account all the horrible things that commonly go wrong while making accidental bottle bombs. The usual infections from wild yeasts and bacteria could easily occur in a pressure rated fermenter, and I couldn't agree more with you about the back up PRV.
With an infection I'd imagine >4bar is very possible.
My fermenter has a corny lid fitted for easy access and the back up PVR. Add to that the valve on the keg coupler and you've got tripel redundancy.

While on the subject of spunding valve blockages, I thought I'd finally post a shot of my garden tap valve. Easily the cheapest and least likely to block valve.
20140309_134108.jpg
She's done three brews now with minor problems along the way, but the valve itself is pretty sound. The main adjustments I've tried are the spring and washer types.
The best combination I've found is the spring out of a regular trigger sprayer (windex, spray and wipe, whatever is going at the time) and the Fixatap Leaklock valves. http://www.fixatap.com.au/cat/tap-valves#prettyPhoto[pp_gal24]/0/

The rest of the assembly is still in development at the moment, but it's got the usual pressure gauge and disconnects. The main add on I use is an airlock that lets me see how much gas is being released.
I find the airlock allows you to make very small adjustments while the pressure is ramping up. It also lets you see the low pressure release that doesn't show up on your gauge.

I hope someone finds this option useful. It has to be the easiest valve to dismantle and clean.
Cheers.

Edit:
The white washer that sits between the tap head and the body is just a silicone jobby from Craftbrewer. Using one means you don't need a spanner to undo the rig.
 
dent said:
El cheapo PRV at work

IMG_0428.JPG
I won't ask about the soldering job. :ph34r:

Would you mind posting the parts list?

A good source of pressure gauges, in the right range, is pool filters. You can buy them new at many places, or just keep an eye out during council clean ups.
 
Here you go

1/2" to 1/4" bush (the part so artfully soldered to the keg)
1/4" Y adapter (one male end, two female ends)
1/4" to 1/8" bush (for the gauge)
gauge
1/4" male to 1/4" female ball valve
1/4" to 1/8" bush
China's finest cheapest pressure cooker jigger valve
 

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