Originally Posted by avfc1982
Hi it's possible but all that you will achieve is to balance or equalise the pressure between the two tanks. Confusingly you will increase the pressure of the lowest pressure tank by 50% of the difference between the higher pressure tanks starting pressure and the lower pressured tanks pressure. I'm sure that's as clear as mud
But that only applies for tanks of equal volume. For unequal tanks the pressure drop is in proportion to the ratio between the internal volumes of the two cylinders. So the pressure in the big one goes down by much less than the pressure in the little one goes up.