I my experience with hookah, we just ran 25-30' of l.p. line coming off of the first stage. One would think if you ran 30' why not 50', and, you can. just be prepared to take the tank with you if you go deeper than 33' because the l.p. line chokes and is hard to draw if your tank is still in the first atmosphere.(when it's getting near empty, also it'll start to become positive and float) I would imagine, not that I've tried, that the same principle would parallel tool air hose, that stuff wasn't engineered to be used under more than one atmosphere of pressure, nor was it designed to be used in conjunction with air intended for breathing. Also in an umbilical, air hose is braided and reinforced and should be checked to 1 1/2 x's working pressure and annually inspected to 2 x's greatest working pressure. Also the fittings are to be checked (I dont remember the exact figures) for strength, some thing to the tune of 500#s if memory serves. Home @#pot doesn't sell anything close to those specs. But if you want to DIY go for it, however, I would skimp on other things besides breathing air. There are several companies on line (a big one is in Louisianna) and would be happy to sell you whatever you want to make a rig or hookah regardless of certification level.
