Abstract: A valve system is provided for operatively coupling a high pressure source to a processing chamber that selectively cycles between high pressure and vacuum. The valve system includes a branch passageway that selectively communicates a source of intermediate pressure to a main passageway that couples the high pressure source to the processing chamber. The source of intermediate pressure may comprise a vent, a pump, or a source of pressurized fluid, etc. An inventive valve for sealing between the intermediate pressure and the vacuum pressure is also provided. The inlet of the valve is operatively coupled to the high pressure source (via one or more valves) and the outlet of the valve is operatively coupled to the processing chamber (via one or more valves). The valve stem is in continuous fluid contact with the inlet and is configured for high pressure sealing, and the outlet is configured for low pressure sealing and preferably comprises a resilient sealing member.

Abstract: A high pressure fitting configured to be weldingly coupled to high pressure tubing is provided. The high pressure fitting and/or the tubing welded thereto may be chamfered to provided a smoother welded joint. The interior surface finish of the fitting is smoothed via an abrasive fluid flowed through the fitting's fluid passageway. In fittings comprising a corner, the inner edge of the corner may be rounded by forcibly flowing an abrasive fluid through the fitting. Electropolishing further smoothes the interior surfaces. The inventive fitting allows flow system tolerancing to be tightly controlled by determining a desired distance between two high pressure fittings to be coupled, and adjusting the desired distance by a welded length variable.