Adjustable gas distribution system

摘要

The present invention provides a gas distribution apparatus comprising a plurality of outlets and at least one replaceable insert placed in at least one of the outlets. The insert is provided with a passageway adapted to alter the size of the at least one of the outlets and/or the direction of gases exiting the at least one of the outlets. The insert is provided with passageway that may be substantial straight and cylindrical. The passageway may have a first portion with a smaller diameter and a second portion with a larger diameter to selectively alter the size of the outlet passage in the gas distribution apparatus. Alternatively, the insert is provided with a main passageway and plurality of secondary passageways branched and angled from the main passageway. The angle between the main and branch passageways is in the range from about 10 to about 90 degrees. In one embodiment, the angle between the main and branch passageways is about 90 degrees.