Consideration of the force balance of the ring plasma presented by meteoroid impact in the rotating ionosphere of Saturn is extended to include the magnetic mirroring effect. It's found that there are modifications to the so-called siphon flow limit derived for charged particles with zero magnetic moment if the ionospheric plasma has a thermal temperature exceeding a few electron volts. The nature of the force balance is such that, instead of a sharp division between complete loss, and complete reabsorption a transition zone of partial loss appears. If part of the ions near the rings are produced by ionization of the neutral atmospheric in the vicinity of the ring system (also generated by meteoroid impact vaporization), another theoretical limit dividing the upward flow from the equatorially confined motion is located near the observed boundary between the B ring and the C ring. This new limit is very sharp, as required to explain the B-C ring boundary, which has not yet explained by gravitational theory.