US Patent 7600995 Hot runner having reduced valve-stem drool

Disclosed is a valve-gated hot-runner system, having: (i) a back-up sealing arrangement, including: (i) a plurality of radial gaps associated with a valve stem of a valve actuator, and (ii) a cooling system being positioned relative to the plurality of radial gaps, the cooling system being configured to freeze a drool being made to enter, under pressure, into the plurality of radial gaps, so that the drool that becomes frozen substantially reduces flow of the drool along the valve stem and toward the valve actuator.