The A7 is an inflation valve, you use it to pump up your tubes.
The A6 is a pressure relief valve, when the air pressure in your tubes get to a certain pressure, the A6 valve will open slightly to let out an amount of air, enough to bring the pressure back down to the limit that's preset in the A6, see
here.
Here's the important bit: You can't inflate your tubes through a pressure relief valve!