I have access to two stainless vessels out of a milk factory that are almost identical to the shape of a morebeer vessel. right now i am brewing five gallon batches and i would love to make one of these into a fermenter. my question being: is "dead space" above the fermenting beer horrible if i can pressurize it? The vessels are at least twice the size of my batches. should i make a smaller one, brew twice, pressurize the vessel, leave it alone, any input would be valued.
-D Hurt

Excess headspace is not an issue. If anything it is required if you brew wheat beers or use certain yeasts which throw a huge krausen.

You don't want to be pressurising the headspace either, use an airlock or similar to allow volatiles and built up gases to escape.

Good luck with the build/fabrication!

Yeah too much pressure on the yeast will be detrimental to them during growth. I'm assuming these conicals have atleast a 10-12 gallon capicity?

good to know...yeah they are at least 12 gallon. didnt know if i should make one little one and keep one as is.

Leave them as is and grow your system into them if needed.

Head space of at least 30% and preferrably more is essential in a fermentor and it should be able to hold pressure (so that beer conditioning in it will become carbonated).

Lots of headspace is a good thing during active ferment. When it becomes less desirable is if you will be keeping it there for a long period of time. Without CO2 being produced (positive pressure), O2 may have more of a chance of diffusing in.

You guys read any of the stuff on pressure fermenting in sealed kegs? There is another theory on this- how much pressure do you think exists in a 200-500 gallon fermentor just from the weight of the wort?