You took some soap with you to check your connections on the air side right? I don't see how there would be a difference from the water side to the air side, it should last just as long.
Well duh! I tried a dozen different ways to make the connections, and I know they were not leaking.
Air molecules can pass through almost any material. It just passes through some materials easier than others. With air in a diaphragm tank, there is water at the exact same pressure on the other side of the diaphram, which keeps the air from coming through the diaphragm.
With a pressure switch on the air side of the tank, there is only air at atmosphereic pressure on the other side of the pressure switch diaphragm, and air will pass right through from the high pressure to the low pressure side, which will let all the air leak out.
When you have water pressure going into a pressure switch, the water molecules are larger and cannot leak through the pressure switch diaphragm.