In an injection molding apparatus comprised of an injection molding machine that injects an injection fluid material into a heated manifold, a nozzle having a fluid flow channel having a longitudinal axis and an upstream end that receives the injection fluid material from the heated manifold and delivers the injection fluid to a downstream end that sealably delivers the injection fluid to a gate of a cavity of a mold body, the downstream end of the nozzle comprising an inner tubular member having an outer circumferential surface and an outer tubular member having an inner tubular surface, the outer tubular member forming a seal (57, 86, 54, 58) surrounding the gate, the inner and outer tubular members being adapted to form a sealed circumferential gap between the outer circumferential surface of the inner tubular member and the inner circumferential surface of the outer tubular member, the circumferential gap circumferentially surrounding the fluid flow channel, a valve pin being disposed within the fluid flow channel, the inner tubular member has one or more apertures extending radially through the inner tubular member between the fluid flow channel and the circumferential gap to enable flow of injection fluid that is injected in an upstream to downstream path of flow through the fluid flow channel to flow radially from the fluid flow channel into the circumferential gap, the circumferential gap and the fluid flow channel being adapted to communicate with each other downstream to form a common stream of flow of injection fluid material that is routed to the gate, characterized in that: the valve pin having a maximum downstream diameter section that has an outer circumferential surface that is complementary to and mates with a complementary interior mating surface of the inner tubular member such that fluid material flow is stopped or substantially reduced when the surfaces are axially aligned forcing flow of fluid material to flow through the one or more apertures and the gap, the apparatus comprising a controller having a program that contains instructions that control axial positioning of the outer surface of the valve pin relative to an inner surface of the inner tubular member to form a flow restriction through the nozzle channel for one or more predetermined amounts of time during the course of an injection cycle sufficient to cause flow of fluid material to be routed through an aperture at an elevated rate of flow through the purge apertures and the gap. the valve pin having a maximum downstream diameter section that has an outer circumferential surface that is complementary to and mates with a complementary interior mating surface of the inner tubular member such that fluid material flow is stopped or substantially reduced when the surfaces are axially aligned forcing flow of fluid material to flow through the one or more apertures and the gap, the apparatus comprising a controller having a program that contains instructions that control axial positioning of the outer surface of the valve pin relative to an inner surface of the inner tubular member to form a flow restriction through the nozzle channel for one or more predetermined amounts of time during the course of an injection cycle sufficient to cause flow of fluid material to be routed through an aperture at an elevated rate of flow through the purge apertures and the gap.