A flow characterizing device for a ball valve comprising a housing and defining a flow path extending through the housing and a rotatable ball valve member within the housing including a spherically shaped ball having a spherical outer surface and a through bore extending through the ball valve member with a center line of the bore substantially aligned with a longitudinal axis of a flow path when the ball valve is in a fully open position, wherein a corner formed by of the edge of the through-bore in the ball valve member with the outer spherical surface of the ball valve member forms a controlling edge of the outer spherical surface, which moves along a path extending transverse to the longitudinal axis of the flowpath as the ball valve member rotates, between a fully open and a full closed position of the ball valve member in the flowpath, the device being adapted for placement in the flowpath between the ball valve member and the valve housing adjacent to the rotatable spherically shaped ball valve member of a ball valve, but not including the ball valve member, the ball valve or the flowpath, the flow characterizing device modifying fluid flow through the flowpath the flow characterizing device comprising: - a body, defining a longitudinal centerline of the flow characterizing device that extends substantially coincident with the longitudinal axis of the flowpath when the flow characterizing device is installed in the flowpath, and a transverse axis of the flow characterizing device that extends substantially coincident with the path of the controlling edge when the flow characterizing device is installed in the flowpath, - the body also defining a datum surface of the flow characterizing device corresponding to the outer spherical surface of the ball valve member when the flow characterizing device is installed in the flowpath, and inner and outer surfaces (110, 112) of the flow characterizing device disposed in a spaced relationship to one another along the longitudinal centerline of the flow characterizing device; the inner surface of the flow characterizing device defining a land surface thereof conforming to a portion of the datum surface and contoured to bear against the outer spherical surface of the ball valve member, for forming a substantially fluid-tight seal between the land surface and the outer spherical surface of the ball valve member, when the flow characterizing device is installed in the flowpath; the inner surface of the flow characterizing device further defining a segmented flow characterizing channel therein, the flow characterizing channel being bounded at least partially by the land surface and the datum surface and including a plurality of discrete segments, extending along the transverse axis, and with each of the discrete segments opening through the datum surface of the flow characterizing device at least one of which being a through-hole extending through the body and providing fluid communication between the inner and outer surfaces (110, 112) of the flow characterizing device, CHARACTERIZED IN THAT: two or more of the discrete segments are connected in fluid communication with the through-hole along a channel axis extending transversely to the longitudinal axis of the flow path, with each of the at least two or more discrete segments including a substantially axially facing wall thereof extending transversely to the longitudinal centerline of the flow characterizing device, such that the flow area provided by each one of the at least two or more discrete segments, when the controlling edge of the ball valve member is aligned therewith, is a transversely facing flow area and provides a uniquely sized, discrete flow area at least partially bounded by the datum surface for controlling a flow of fluid through the flowpath, wherein the controlling edge and the segmented flow characterizing channel is selectively movable along the channel axis. - a body, defining a longitudinal centerline of the flow characterizing device that extends substantially coincident with the longitudinal axis of the flowpath when the flow characterizing device is installed in the flowpath, and a transverse axis of the flow characterizing device that extends substantially coincident with the path of the controlling edge when the flow characterizing device is installed in the flowpath, - the body also defining a datum surface of the flow characterizing device corresponding to the outer spherical surface of the ball valve member when the flow characterizing device is installed in the flowpath, and inner and outer surfaces (110, 112) of the flow characterizing device disposed in a spaced relationship to one another along the longitudinal centerline of the flow characterizing device; two or more of the discrete segments are connected in fluid communication with the through-hole along a channel axis extending transversely to the longitudinal axis of the flow path, with each of the at least two or more discrete segments including a substantially axially facing wall thereof extending transversely to the longitudinal centerline of the flow characterizing device, such that the flow area provided by each one of the at least two or more discrete segments, when the controlling edge of the ball valve member is aligned therewith, is a transversely facing flow area and provides a uniquely sized, discrete flow area at least partially bounded by the datum surface for controlling a flow of fluid through the flowpath, wherein the controlling edge and the segmented flow characterizing channel is selectively movable along the channel axis.