Tank pressure

Godzookie

If a diaphragm or bladder tank is rated at 150 psi, can it have 150 psi of air AND 150 psi of water?  Or do you add the two pressures together?  For instance, if my water pressure going into the tank is 150 psi, can I also put 150 psi on the air side and still be within the pressure guidelines?  Thanks!

lchmb

relief valve

your relief valve is rated to release at 150psi for domestic hot water...dont want it that high...