what is fire hydrant in industries and how it works?
This is an abstract answer that i actually think is pretty good. I was told that Roger Penrose said this: 1. Eventually everything in the universe will be inside a lot of black holes 2. Black holes evaporate by hawking radiation 3. When all the black holes evaporate the universe will be filled with randomly distributed radiation NO matter! 4. There are NO observers. 5. These conditions are the same as the big bang singularity. So, while the universe never actually collapses, there is some sort of cycle. Obviously this is an abstract theory, though i think it is the most complete one so far.
but no barbed fittings, I'll look some more and get back to you. Meanwhile some of those fittings may help in your designs.