Abstract: An automatic switching valve mounted between two fluctuating pressure sources automatically switches from one source to the other to supply gas or liquid from the source that is under the higher pressure. A T- housing conveys gas or liquid from either side and out of the central stem. Tapered, spring loaded plugs or valves in either side engage with tapered seats and are maintained in contact with the seats by springs which permit one or the other valve to open when the pressure on one valve exceeds the tension of the spring of the other valve. If the pressure is equal on both sides, both valves will open simultaneously if pressure is greater than cracking pressure.