Blowing agent delivery system

A system for processing polymeric foam material comprising:

• an extruder including a barrel and a screw designed to rotate within the barrel to convey polymeric material in a downstream direction within a polymer processing space between the barrel and the screw, the extruder having a port in the barrel positioned to introduce a blowing agent into polymeric material in the polymer processing space to allow formation therein of a solution of polymer and blowing agent;
• and
• a shut-off valve having an inlet fluidly connected to a blowing agent source and an outlet fluidly connected to the port, the shut-off valve designed to selectively permit or prevent the flow of blowing agent therethrough,
• wherein a fluid pathway distance from the shut-off valve to the port in the barrel is no more than 3 inches.

A method of forming polymeric foam material comprising:

• conveying polymeric material in a downstream direction in an extruder within a polymer processing space between a screw and a barrel;
• introducing a blowing agent into the polymeric material in the polymer processing space through a blowing agent port;
• and
• preventing the flow of blowing agent to the blowing agent port at a distance of less than 3 inches from the blowing agent port.