Like others posted in this thread (I think)...the brite tank is always CO2 pressure positive, even during cleaning. We only open her up once every month or so for a full caustic/acid/ster cleaning...otherwise, it's rinse/acid/PAA between fills...all under CO2 pressure. We just opened her up last week (120BBL brite) after a lapse of 2 months...besides some sludge pockets around the thermowell and carb stone...she was squeaky clean.
For transfers, connect headspace, turn your pump on with a low VFD setting about 30 mins transfer for 120BBLs.
As far as purging...we do this only when we open her up for the full cleaning...from the bottom-most port with the CIP arm vented...set your regulator to about 2psi and come back the next morning...she should be done by then. Close off the CIP arm, crank it up to 15psi and get ready to transfer.
I always wonder, is there a better way to do this? I've heard some guys push beer from unitank to bbt while venting off CO2 from the bbt...i just thought maybe that was a waste of CO2 because then you have a dirty empty unitank full of co2 that you now have to clean...does that make sense? and you probably don't want to skip the caustic step on fermenters because of all of the krausen, yeast, and fermentation debris (hops, break, etc...). Does anybody out there not caustic cycle their fermenters after each use...please advise.
Alex Postelnek, Lead Brewer
Funky Buddha Brewery
Ft. Lauderdale, FL 33334
(561) 945 - 4584