Nitrogen leak after replacing carrier gas filter

We had a H2O leak of 17% and our carrier gas filter was saturated with moisture. At this time, N2 and O2 levels were both well below 5%.

We had a N2 leak after replacing the saturated filter with a new Gas Clean Filter (H2O and O2 levels were <5%). We followed the instructions, entered the split flow to 400 mL/min to purge the filter. The N2 level significantly dropped to <5%, however, after we return to splitless mode the N2 levels creep back up to ~40% and remains there. We have purged multiple times and the same situation occurs. The only change we made was replacing the new filter- nothing else was touched.

Has anyone experienced this before and can you offer any solutions, please?

Thank you for your help Slight smile

  • Splitless mode -- you mean while the inlet is in purge off - waiting for injection?  Or when your system is in standby with the gas saver flow 20 ml/min?

    What is your inlet pressure?  Column flow setpoint and column configuration?  How long since the inlet liner and O ring and the septum were replaced?  (and the septum not overtightened)

    N2 levels crept up, but what about O2?   The Gas Clean filters are packaged in nitrogen and it can take significant time for it to be completely gone - like some days if the flows are low.  When I purge a new filter I let 400 ml/min rip for at least 20 to 30 minutes or so.

    There's another process that will help, too. 

    Disconnect the copper line at the back of the GC - after the trap, turn the gas supply flow on, put your gloved thumb over the exit to pressurize the plumbing and the gas clean trap, turn the gas off, thumb off to release the pressure, thumb on, gas on to pressurize, then repeat a number of times.  Those pressurize/depressurize cycles help release the nitrogen from the unswept pores in the filter material.  It’s not hard when the tank is near but annoying if it’s too far away. It's best for you to have a ball valve right before and after the trap to make that a bit easier.   

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