we want to analyse a gas mixture (CO2, CO, propane, ethane and methane in hydrogen) with the HP 6890 Series GC System (G1540A). The gases are coming to the column via a six-way valve and after the column, there is a TCD and a FID detector. In between the two detectors, there is the methanzier (back inlet).
After setting up the whole system there was a problem with the back inlet temperature appearing, because it was always a litte bit lower than the setpoint and fluctuating (~5 °C). 360 °C was choosen as temperature for the methanzer, but with that it could only reach around 352 °C. The problem is not that the temperature is too high, because if 380 or also 340 °C is choosen, the temerature is again around 8 °C lower. Just if there is a lower temperature than ~300 °C, the temperatuer was reached perfectly, but with such a low temperature, the methanziner will not work as it should.
Thanks for your help!