A strip of PTFE-based polymer seated in a groove along the edge of each scroll, rubbing against the opposite scroll plate to seal the moving gas pockets. Tip seals wear in service, typically lasting one to three years, and shed fine dust into the exhaust and sometimes back toward the inlet. Wear shows up as a rising ultimate pressure and slower pump-downs, and swapping them is a routine kit job.
Pulled the scroll head, tip seals were worn to nothing and there was black dust all down the inlet.
Also heard as
- tip seals
Related terms
Scroll pump
Dry pump that compresses gas between a fixed spiral and an orbiting spiral, with no oil in the gas path.
Dry pump
Vacuum pump with no oil or liquid in its pumping chamber, used where oil vapour would contaminate the process.
Ultimate pressure
The lowest pressure a pump can reach on a sealed, clean test dome, as stated on its data sheet.