The shell weldment in an Agilent 5890 GC is a boxlike part that attaches to the top of the GC with screws. The inlet body projects down from the shell weldment and extends into the injector heater block. The liner (typically glass) is placed in the inlet body. The gas line port that projects from the side of the shell weldment, near the top, is the split vent. The weldment, which looks like a cap, screws down on top of the shell weldment. The septum is placed in the weldment and is held in place with the septum nut. The gas lines that connect to the weldment are for the carrier gas and septum purge gas. (The carrier gas line has the smaller ID.)
