Hum, don't know. I do know that if the cf bottle is a SCBA there is a two inch pipe in the valve that protuded into the bottle to prevent exactly that. so no, holding it upside down won't work, until the pipe is removed......Knife
Gary, I would not think so. a SCUBA tank isn't used up side down like a SCBA bottle, so a water intake prevention tube would have no reason to be there, as it would not do anything to prevent water intake in the air stream. The Bengi tank, is not a breathing air tank, so again, it would serve no purpose.Knife
Some scuba valves have dip tubes and some don't. The dip tube is there to prevent any particles in the tank from getting into the regulator when the diver is head down. Easy to remove/install.