US Patent 7850449 Heat treatment equipment

In an embodiment, heat treatment equipment comprises a process tube, an exhaust duct connected to the process tube, and, during operation, exhausting gases present within the process tube. The heat treatment equipment also comprises a hollow pressure control member interposed between the process tube and the exhaust duct, the pressure control member being operatively connected to the process tube and the exhaust duct respectively, and including one or a number of openings. Negative pressure is avoided in the process tube during heat treatment processes so that unwanted gas and impurities cannot enter the process tube from outside.