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Thermo Fisher Scientific

Foreline Pump Vacuum Issue


The Fore vacuum of my MS is showing a high value.




  • Check all parts or components you could have manipulated before. 
  • Check noise level of the pump, check oil level and if oil is not leaking from the pump.
  • Check vacuum tubing and hose clamp. 
  • Check if the vent valve knob is tightened. 
  • Tighten the transfer line nut, check / replace columns ferrules. 
  • Clean the glass top cover O-ring. 
  • Check/clean front door o-ring if it was opened. 
  • Check the helium pressure/flow applied in the column.
  • Check the argon applied pressure.
  • Check the CI gas is turned off if CI module is present.
  • Check if the issue is coming from MS or GC: Shutdown down the MS, remove the column from the transfer line and put a plug instead. Argon or air spray gas can be used around the vacuum manifold to look for characteristic ions (40-100).


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