Abstract: An actuator regulating valve apparatus comprising an actuator assembly operably installed within a valve body assembly, a bellows assembly operably installed adjacent to the actuator assembly, a biasing assembly operably installed on the valve body assembly substantially opposite the bellows assembly and configured to bias the apparatus closed, and a non-compressible liquid filling the apparatus about a bellows of the bellows assembly and the effective working surface of a piston of the actuator assembly and communicating therebetween through an orifice. Alternatively, an actuator rolling diaphragm is configured so as to partially cover the piston and to have a convolution loop supported by a U-shaped insert within a groove about the piston. Further alternatively, a balancing diaphragm sub-assembly of the biasing assembly acts on a pushrod of the actuator assembly to produce a force substantially equal and opposite to the pressure in an inlet side of the apparatus.