The advantage of using a duplex fuel selector valve with a fuel injected engine such as the 912iS, is to return the unburnt fuel to the same tank from where it came from. Andair's FS20 valveis not just a selector valve, it also has an OFF position. In the off position no more fuel will reach the engine and also the return fuel line is blocked. Without a bypass for the return line the fuel pressure will bild up very quickly and cn create a dngerous condition unless a check valve is built to bypass the return sshutt-off valve. Please note you will need to use a check valve with 14 PSI back pressure in order to preven fuel to be returned only through the bypass in case the return lines are shut off and the fuel pumps are still running and build up pressure.
