Vacuum pump
Rotating impeller throws sealant liquid (usually water) into a ring that compresses gas. Handles wet, dirty, condensable loads.
Typical range
1–500 HP, down to 30 mbar (single-stage)
Best for
Paper mills, chemical processing, condensers, anywhere the process gas is wet or carries slugs of liquid.
Operating principle
An impeller spins sealant liquid (water/glycol) into a ring against an eccentric casing. Gas enters the port, is trapped between blades and the liquid ring, compressed, and discharged. The liquid absorbs heat and can handle condensables and slugs.
Efficiency notes
Capacity depends on seal-liquid temperature (vapor pressure). Warm seal liquid raises ultimate pressure and cuts capacity. Two-stage for deeper vacuum.
Selection guidance
Wet, dirty, or condensable loads: paper mills, chemical, condenser evacuation, power-plant hogger duty.
Components
- Impeller
- Cone or port plate
- Service-liquid supply & separator
- Heat exchanger (closed-loop systems)
- Mechanical seal
Common issues
- Capacity drop → service liquid too warm (raises vapor pressure)
- Cavitation noise → operating too close to vapor pressure of seal liquid
- Seal leak → worn mechanical seal or shaft sleeve
Maintenance
- Maintain seal-liquid temperature per OEM (usually <60°F / 15°C for water)
- Check seal-liquid flow rate at every PM
- Inspect mechanical seal annually
Field tips
- Keep seal liquid cool (<60°F/15°C for water) — capacity collapses when warm
- Cavitation noise means operating too close to the seal-liquid vapor pressure
- A closed loop with a heat exchanger saves water and controls temperature