Agilent Technologies 6890 Series Service Manual page 90

Gas chromatograph

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Cool On-Column Inlet

Programmable Cool On-Column (PCOC) inlets are designed to allow the

injection syringe to deposit the liquid sample directly into the capillary

column. This is accomplished by the use of an insert which serves to align the

syringe with the capillary column and the syringe needle.

Theory of operation

At injection, liquid sample is introduced directly into the column.

For manual injections, a duckbill valve (isolation valve) uses inlet

pressure to create a pneumatic seal around the needle.

For automatic injections, the duckbill valve is replaced with a septum

and nut and the septum maintains the pressure seal.

For both manual and EPC inlets, the flow paths are the same; the flow is

divided into two streams. The carrier gas enters the inlet and flows into the

column and additionally provides for a constant septum purge flow regardless

of the column flow rate you use.

Agilent 6890 Gas Chromatograph Service Manual

Troubleshooting

6890a 6890 plus