System for the non invasive control of the tightness condition of apparatus, in particular of the constancy of said condition of m homogenous series, each one of n apparatus, which in the absence of said pressure constancy would have not acceptable, not uniform characteristics and performances, especially of electronic mechanical, hydraulic and similar apparatus. The system includes (a) a first sub system including a pneumatic chamber, set at a sampling reference pressure, for the pressure control of each one of said n apparatus of each one of said m homogenous series; (b) a second sub system of treatment and feeding of pneumatic fluid to said chamber in order to support and stabilize said reference pressure; and (c) a third sub system of comparison and detection of undesired deviations over said reference pressure, of the detected pressure in the chamber occupied, on turn, by each one of the n apparatus of each of the m series.