Figure 11 16 debris ladden door seal.
Vacuum furnace door seal grease.
If the pumping system is operating correctly then one of these failure modes is likely the cause.
Wipe the door o ring and flange with a clean lint free rag before closing the door.
Here the vapor pressure of the grease should be noted increases greatly with the temperature and should be well below the desired operating pressure.
The types of lubricants for vacuum service fall into three general categories.
A damaged door seal vacuum furnace leaks and or hot zone contamination.
Click here to access the step by step instructions for the o ring or lip seal installation on a rotating vacuum furnace door.
2 if the door has a true autoclave design whereas the locking ring rotates around the stationary door then either vacuum grease and or graphite dust may be utilized.
Clean the chamber door or bottom head flange and lightly grease the o ring with a thin coating of high quality vacuum grease.
Molybdenum disulfide tungsten diselenide and c metal on metal combinations.
Inspect and wipe clean this seal each time the door is opened after a furnace cycle.
The role of lubricants in vacuum furnace seals.
As such it tends to be the cause of pump down issues about 80 of the time.
Despite what one may think excess vacuum grease does not aid in sealing and should be removed as it is a getter for shop debris which will interfere with the o ring s ability to seal.
Reapply a thin coating of vacuum grease as necessary.
How to seal a leaking o ring with grease.
Graphite powder should be used on the lip seal.
Do not grease the lip seal.
The door seal on a vacuum furnace sees some of the highest wear and tear through normal operation.
The vacuum grease smooth out small irregularities on the sealing surfaces and the surface of the o ring and thereby improves particularly at low degrees of deformation the sealing effect.
On o ring seals look for cracks lack of elasticity flat spots dirt and metallic fines.
The first q a community for vacuum furnace end users and operators.
1 if the door that houses the lip seal rotates the lip seal should be lubricated with dry graphite powder.
Check the o ring vacuum seal on the furnace door for grit and dirt that might cause vacuum leaks.