Abstract: A flow regulating apparatus for a fluid, in particular a pneumatic choke valve, includes a housing having an inlet port and an outlet port fluidly connected by a choke channel. A throttling piston is disposed in the choke channel for movement in longitudinal direction between an initial position and an end position. The throttling piston includes a tapered section to define with the choke channel an overflow passage whose cross section is dependent on a position of the throttling piston, wherein the tapered section is configured such that a movement of the throttling piston from the initial position to the end position results in a progressive increase of the cross section of the overflow passage.

Abstract: A pneumatic valve, includes a housing having first and second ports for entry and exit of an operating gas, a main connection line for linking the ports, and a cross bore intersecting the main connection line. A throttle includes a control element which is received in the cross bore and has a control opening with an effective area which progressively decreases from a first end position to a second end position, as the control element moves in a direction toward the second end position, whereby a counterforce is provided to oppose this movement of the control element. Disposed in the main connection line in series with the throttle is a flow orifice, wherein a gas pressure differential upstream and downstream of the flow orifice, as viewed in movement direction of the control element, is utilized to control the effective area of the control opening.