Vacuum technology
Multi-stage Roots (Dry)
Dry lobe stages in series. Clean process vacuum.
Schematic section, not to scale
How it works
Multi-stage roots (lobe) pumps put several pairs of lobed rotors in series inside one casing, compressing the gas stage by stage without oil or water in the pumping chamber. They are a mainstay of semiconductor, flat-panel and other clean process duty.
Pairs of figure-eight or tri-lobe rotors turn in opposite directions without touching, each stage taking gas from the one before and passing it on at higher pressure, from atmosphere down to the low millibar range or below.
Performance range
Atmosphere to roughly 0.1-1 Pa ultimate; pumping speeds from about 100 to several thousand m³/h
Typical industry range. Exact capability is model specific, see each model’s curve.
In the catalogue · 39 models from 3 manufacturers
- Pumping speed
- 6.6 – 6,600 m³/h · 39 models
- Ultimate pressure
- 0.003 – 0.05 mbar · 39 models
- Weight
- 19 – 870 kg · 39 models
- Noise level
- 55 – 72 dB(A) · 7 models
Spread of each model’s own rated figure, as published by its manufacturer.
Advantages & tradeoffs
- No oil in the gas path
- Tolerant of process by-products with temperature control
- Low maintenance
- Higher purchase price
- Sensitive to particles that can lodge between stages
- Heat management matters on harsh processes
Best applications
Maintenance
Periodic inspection, purge gas and temperature control checks, overhaul at long intervals.
Energy characteristics
Specific-energy comparisons (kW per unit of flow at your operating point) appear here as sourced performance curves are added. Until then, compare models directly on the Performance Map.
Open the Performance Map