A dry positive displacement pump built from two interleaved spiral scrolls: one is fixed and the other orbits, so crescent-shaped pockets of gas shrink as they travel from the outer edge to the exhaust at the centre. With no oil in the swept volume it reaches about 10⁻² mbar without contaminating the chamber, which makes it the standard backing pump for clean turbo systems in labs. Its weak point is the polymer tip seal, which wears and sheds dust.
Scroll's ultimate crept up to 0.3 mbar, I'd bet the tip seals are worn, we're nine months in.
Also heard as
- scroll
- dry scroll
Related terms
Tip seal
Polymer strip along the edge of a scroll pump's spiral that seals each gas pocket against the facing plate.
Dry pump
Vacuum pump with no oil or liquid in its pumping chamber, used where oil vapour would contaminate the process.
Backing pump
Pump that keeps the exhaust of a turbo, diffusion or Roots pump below its maximum allowed pressure.
Rotary vane pump
Oil-sealed positive displacement pump in which sliding vanes sweep gas around an off-centre rotor.