using the "find all words" for wine and pillow gave a bunch of hits. I didn't read them all, but this tidbit seemed helpful:
Yes, the bladders from boxed wine make fine pillows as well as reliable water carriers. And they keep that pleasant, faint overtone of the oak barrels in which the wine was aged. Look for the kind with rubber valves. They look like thick disks. The plastic stopcock-type valve assemblies found on some brands do not come off easily and stop sealing after a few uses. Platypus containers work well, too, and that's what I am using these days."
From Vick Hines in this thread:
There were several other threads too, maybe one of them is what you're looking for. It sounds like the valve type might help answer some of your questions though, good luck!