Gas delivery metering tube

摘要

A gas delivery metering tube is provided. The gas delivery metering tube includes a two axially aligned nested tubes wherein the inner and outer tubes receive a gas through one end of the assembly and the inner tube conveys gas to the opposite end of the outer tube. The outer tube contains one or more arrays of orifices. Conveying gas to the end of the outer tube opposite that connected to the gas inlet provides for more even backing pressure over the entire length of the gas delivery metering tube than can be achieved by allowing gas to enter only through a single inlet.