A dry screw vacuum pump operates on the principle of positive displacement using two intermeshing screw rotors that rotate in opposite directions to compress and move gas from the inlet to the outlet without any internal lubrication (oil-free).
The process starts when the rotors (screws) rotate in opposite directions (timed by synchronized gears).
As the screws turn, they create an expanding cavity at the inlet side, drawing gas into the pump.
The intermeshing rotors form sealed chambers that trap and isolate the gas between the screws and the pump housing.
As rotation continues, the trapped gas is axially pushed toward the discharge side while the volume between the rotors decreases, compressing the gas.
The compressed gas reaches the outlet port, where it is expelled into the exhaust system.
Since there is no oil or liquid inside the compression chamber, the discharged gas remains contamination-free.
Compression generates heat, so most dry screw pumps use:
Air cooling (fins or fans) for smaller pumps.
Water cooling jackets for high-capacity industrial pumps.
Two Helical Rotors (Screws) – Primary compressing elements (usually left-hand & right-hand threads).
Timing Gears – Ensure rotors rotate in sync without touching, preventing wear.
Inlet & Outlet Ports – For gas intake and discharge.
Cooling System – Air or water cooling to manage heat.
Motor & Drive System – Provides rotational power (often with variable speed control).
Seals & Bearings – Isolate the pumping chamber from the motor (no oil contamination).
Unlike oil-sealed rotary vane pumps, dry screw pumps:
Do not use sealing oil in the compression chamber.
Eliminate oil mist & contamination (critical for clean industries like semiconductors and pharmaceuticals).
Reduce maintenance (no oil changes or oil filters needed).
| Feature | Dry Screw Pump | Oil-Sealed Rotary Vane | Liquid Ring Pump | Scroll Pump |
|---|---|---|---|---|
| Oil-Free? | ✅ Yes | ❌ No (oil-lubricated) | ❌ No (water/oil) | ✅ Yes |
| Ultimate Vacuum | 0.1 mbar (0.01 kPa) | 0.001 mbar | 30 mbar | 0.01 mbar |
| Maintenance | Low (no oil changes) | High (oil & filters) | Medium (seal wear) | Medium |
| Handles Wet/Corrosive Gases? | ✅ Yes | ❌ No | ✅ Yes | ❌ Limited |
| Energy Efficiency | High | Medium | Low | Medium |
✔ Oil-free operation – No contamination risk for sensitive processes.
✔ Handles corrosive & condensable gases – No oil degradation.
✔ Low maintenance – No oil changes, fewer wear parts.
✔ High pumping speed – Efficient even at low pressures.
✔ Quiet & vibration-free – Smoother than piston or claw pumps.
❌ Higher initial cost than oil-sealed pumps.
❌ Heat generation – Requires cooling (air/water).
❌ Not for ultra-high vacuum (UHV) – Turbomolecular pumps are better below 0.001 mbar.
Semiconductor Manufacturing (CVD, etching, ion implantation).
Pharmaceuticals (Freeze drying, solvent recovery).
Chemical Processing (Distillation, vacuum filtration).
Food & Packaging (Vacuum sealing, dehydration).
Industrial Processes (Degassing, composite molding).
The dry screw vacuum pump works by trapping, compressing, and expelling gas using two intermeshing rotors without oil, making it ideal for clean, high-efficiency vacuum applications. It outperforms traditional oil-sealed pumps in contamination-sensitive industries but requires proper cooling and has a higher upfront cost.
Looking for recommendations on models or maintenance tips? Let me know your specific needs!
The above content was compiled and published by Zhilong Oil Drum Pump Supplier.