Chromatography Forum

Hello:

We tried to back flush the the transfer line from the GC to P&T by pushing methanol. This did not work and methanol came out. We turned on the flow to GC and the rest of the methanol came out. We are not able to keep the flow to gc any more! We do get enough flow to the head of the column, but the gas is constantly coming out of split valve; so the system shut itself off after about a minute. We have turned off and on the system a few time without any success. Any suggestions is greatly appreciated.

When you back flushed the transfer line did you disconnect it before or after the 6 port valve?
Shouldn't there be flow out the split vent? You are running a split injection.
Does the GC shut down because it can't hold pressure?

Thank you very much Steve for the reply. We were getting over 1000 ml of flow from the split line but the system was reading zero! We are running split and system was shutting down due not being able to get any reading from the split flow. We had to change the EPC to fix this problem.

When doing a methanol flush of the transfer line, disconnect at the 6 port valve inside the purge and trap and remove the top of the injection port then push methanol through from the purge and trap side to the inlet side.

If you are pushing back from the inlet side and push the methanol past the 6 port valve in the autosampler it can go back into the EPC and cause problems there. The EPC isn't designed to handle solvent inside it, at least not handle it well.

You are correct James. Thank you.