Im trying to make an apparatus that would allow you to breathe in from one tube and exhale through another is their a valve that does this. I originally thought that a one way valve might work however I cannot find one that works with suction.
Position two backflow preventers in oposite directions on your supply and exhaust line. connect them to a Tee fitting. the third end of the tee is where you will breathe
If I get your idea right, you would have two separate one way valves, one in each tube, facing in opposite directions. When you inhale the valve that opens provides air from that tube and the other one remains shut because the suction is pulling it closed. When you exhale, the inhale valve is pushed closed by the air pressure from your lungs and the exhale tube valve opens from the pressure provided by your lungs. Consider spring loaded valves if there are problems with the pause inbetween enough positive and negative air pressure in the tubes.
