Originally Posted by HopBlooded
I've been pretty disappointed with the clarity of my last few batches and have decided to cold crash the IPA I brewed to see if that helps. It's a 10 gallon batch in a 14 gallon Blichmann Fermenator. I didn't want to suck any sanitizer (or bad guys) through the airlock, so I capped everything off, essentially making an airtight vessel, before sticking it in the refrigerator. My worry is the vacuum that is created when the temp drops and damaging something, but I have to believe that the fermenter is solid enough to handle it. Or is it? What's the best practice here?
You certainly won't damage the fermentor. You'll get noticeable pressure differentials as your headspace contracts, but it won't hurt in any way your blichmann-tough conical. I don't own one, but I've kicked the tires on a few and I suspect you could stage live-ammunition recreations of famous civil war battles in one of those things without scuffing metal.
One thing worth considering, though, is how you're going to open the valve. You'll suck in a lot of air as soon as you do, which will (to some extent) defeat the whole purpose of sealing off in the first place. Bobby_M had a thread around here somewhere trying to figure out this problem. IIRC, the HBT team came up with some pretty elaborate solutions.