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Septum purge negative flow

Question asked by stevenwlloyd on Feb 14, 2019
Latest reply on Mar 1, 2019 by stevenwlloyd

I am operating a 7890/5975 with a Tekmar Atomx XYZ interfaced to the front inlet. The septum purge actual flow reads -11 ml/m when the setpoint is off and about -1 psi when the setpoint is 3.0 ml/m. The inlet has a Merlin Microseal but the same thing happens with an Agilent 5183-4757 septum. I have replaced the inlet liner and O-ring. The weldment and inlet interior are clean. The carrier is helium. The condition persists at the column flow of 1.0 ml/m and at a pressure surge of 50 psi. The Atomx standby flow is 10 ml/m. I can turn off the septum purge in order to run samples. This is an intermitant problem. Has anyone seen this before and know how to fix it?