Pressure Fermentation vs. Blow-off Cane in Unitank

[aclarson]

Hello, I just preordered 2 of the new 14 gallon Unitanks coming out from SS Brewtech next month. The fermenters can be pressurized up to 15 psi recommended (30 psi max). I've been reading about the virtues of pressure fermentation and I'd imagine it'll take some time to figure out if I like the process, however I was curious how other's who do pressure fermentation handle the blow off cane.

Obviously the blow off cane can't work in conjunction with a pressurized fermentation, I'm just wondering why I would ever want to use a blow off cane if my Unitank can handle the pressure. The Unitanks have a PRV and pressure gauge. Does anyone perceive a benefit of using a blowoff in any circumstances? Even if I'm not connecting CO2 directly, is there any reason I wouldn't want to allow the fermentation pressure to carbonate the beer rather than simply blowing off and being wasted? Do any undesirables escape from the blowoff?

Furthermore, if I leave the blowoff in place during pressure fermentation, that TC fitting will be wasted if I'm simply closing the valve at the end of the cane. Despite that cane being dead sexy cosmetically (see photo), I'm tempted to replace the blow-off cane with a TC sightglass so I can get a peek at the fermentation.

I realize this is a complicated topic, but any help anyone could provide would be greatly appreciated, thanks!

 

[mredge73]

You will need to install a spunding valve on your blowoff cane or at the top TC fitting where it is mounted. You can't just close it; you will climb past 100psi in no time.
The PRV is an emergency device, it isn't adjustable and you don't want to rely on it to control fermentation pressure.
Alternately you can build a combination spunding valve and pressure gauge on the other TC.
How exactly is this sight glass thing that you want to add supposed to work?

15psi will not fully carbonate beer at ale fermentation temperatures; you need a little over 30psi for that.
All transfers will have to be done under pressure as well. Best way to do this is to drop the temp to near freezing and the pressure will drop under 5psi allowing you to transfer using as little as 10psi.
Once you transfer to your serving keg or brite tank you will still need to force carbonate. You won't need as much C02 to force carbonate as you would if you didn't pressure ferment.

 

[Meadymatt]

Mredge73, if i just set the spunding valve to say 15psi, i shouldn't need the blow off valve until i decide to add ingredients later in the fermentation to get rid of pressure? Also, i've totally made mead bombs before out of glass bottles in my pantry, I would literally be blown away to see 100 PSI unitank detonate. lol ;P sounds like an extremely tragic accident.

 

[pocketmon]

Carbon dioxide, CO2, inhibit some kind of metabolism of yeast. The higher pressure, the more CO2 in solution. That is the reason you might want to ferment under "no" pressure.