Air Blower Manufacturer & Supplier from China
If you need a machine that can switch between blowing and vacuum service, our roots blowers and turbo blowers are designed for that dual-purpose role. But if you need dedicated, deep, or chemically tolerant vacuum from a positive displacement vacuum pump manufacturer with CE and ISO 9001 certification, you're in the right place.
Why Positive Displacement?
"Positive displacement" means the pump moves gas by trapping a discrete volume and forcing it from the inlet to the exhaust. There's no high-speed impeller relying on kinetic energy transfer — just mechanical compression. This gives positive displacement vacuum pumps two inherent advantages:
- Deeper vacuum — they can pull down to pressures that kinetic (centrifugal/turbo) vacuum pumps cannot reach
- Constant displacement per revolution — the pumping speed curve is relatively flat across the vacuum range, which matters when your process vacuum level varies
Both the rotary vane vacuum pump (oil-sealed, sliding vane) and the liquid ring vacuum pump (water-sealed, eccentric impeller) belong to the positive displacement family. They solve fundamentally different process challenges.
Rotary Vane vs Liquid Ring (Water Ring) — Quick Comparison
| Rotary Vane Vacuum Pump | Liquid Ring / Water Ring Vacuum Pump | |
|---|---|---|
| Sealing medium | Oil | Water (or process-compatible liquid) |
| Ultimate vacuum | Very deep (sub-mbar, ~0.5 mbar single-stage) | Moderate (~30–50 mbar absolute) |
| Gas tolerance | Clean, dry air only | Wet, corrosive, saturated vapors OK |
| Maintenance | Regular oil changes (500–2,000 hrs) | Minimal — check seal water quality |
| Typical buyers | Food packaging, labs, dental, printing, HVAC | Chemical plants, pharma, paper, mining, power generation |
| Purchase price | Lower | Moderate |
| Operating cost | Oil + filter changes | Water + electricity (less energy-efficient) |
| Best for | Deep vacuum, clean gas, intermittent duty | Wet/dirty/corrosive gas, continuous duty, hazardous environments |
Rotary Vane Vacuum Pumps
Rotary vane vacuum pumps are the most widely used industrial vacuum pump type — and for good reason. They're oil-sealed, compact, quiet, and capable of pulling a deep vacuum that kinetic pumps simply cannot match.
An off-center rotor carrying spring-loaded sliding vanes rotates inside a cylindrical housing. The oil does triple duty: it seals the microscopic clearance between vane tip and housing wall, lubricates the sliding surfaces, and carries away the heat of compression. The result is a pump that can reach an ultimate vacuum of ~0.5 mbar in a single-stage configuration and ~0.005 mbar in a two-stage.
Common uses: vacuum packaging, medical and dental suction, printing and paper handling, refrigeration/HVAC evacuation, vacuum lifting and hold-down, laboratory work.
Available in:
- Single-stage rotary vane vacuum pump — industrial vacuum to ~0.5 mbar, covers 90%+ of applications
- Two-stage rotary vane vacuum pump — high vacuum to ~0.005 mbar, for freeze drying, vacuum furnaces, coating
→ Browse Rotary Vane Vacuum Pumps — Single-stage & two-stage, oil-sealed, deep vacuum
Liquid Ring (Water Ring) Vacuum Pumps
Liquid ring vacuum pumps — also called water ring vacuum pumps or water ring type vacuum pumps — solve a problem every other vacuum pump has: what do you do when the process gas would destroy an oil-sealed pump within hours?
The answer is simple in principle. Instead of oil, you seal the pump with water (or a compatible liquid). An eccentrically mounted impeller spins inside a partially water-filled cylindrical housing. Centrifugal force throws the water outward, forming a spinning ring against the housing wall. Gas trapped between the impeller blades and the water ring is compressed as the impeller rotates — no metal-to-metal contact, no oil to contaminate, and no hot spots from compression because the water absorbs the heat.
What a liquid ring pump handles that other vacuum pumps cannot:
- Wet gases and saturated vapors — steam, water vapor, solvent vapors pass through without condensing in oil
- Corrosive gases — HCl, SO₂, chlorine, acid vapors (with stainless steel construction)
- Entrained solids and particulates — captured in the water ring and flushed out continuously
- Potentially explosive mixtures — near-isothermal compression eliminates ignition sources
- Condensable vapors — solvents dissolve in seal water rather than fouling internal surfaces
Available in:
- Single-stage — ultimate vacuum ~30–50 mbar absolute, for general chemical duty, filtration, conveying
- Two-stage — ultimate vacuum ~10–20 mbar absolute, for distillation, drying, evaporation under vacuum
→ Browse Liquid Ring / Water Ring Vacuum Pumps — Water-sealed, corrosion-resistant, tolerates wet and dirty gas
What These Are NOT — Routing Guide
If you arrived here searching for a vacuum pump but your application or the technology you had in mind doesn't match what we've described above, here's where to go instead:
You're looking for a Lobe Vacuum Pump or Roots Vacuum Pump
Lobe vacuum pumps (also called rotary lobe vacuum pumps or roots vacuum pumps) use two figure-8-shaped lobes rotating in opposite directions. They're a different technology from rotary vane or liquid ring — they run dry (no oil or water in the compression chamber), are often used as booster pumps in series with a backing pump, and are closely related to roots blowers. → See our Roots Blower Vacuum Pump
You need a Turbo Vacuum Pump or High-Speed Vacuum Pump
Turbo vacuum pumps use a high-speed impeller (often on air bearings or magnetic bearings) to generate vacuum through kinetic energy transfer. They're oil-free, can switch between blowing and vacuum, and are ideal for clean applications at moderate vacuum levels. → See our Air Suspension Vacuum Pump and Magnetic Bearing Turbo Blower pages
You need a Centrifugal Vacuum Blower or High-Pressure Vacuum Blower
These are centrifugal or roots blowers configured for suction-side operation — different from the positive displacement vacuum pumps on this page. → See Centrifugal Blowers or Roots Blowers
You want a machine that can do BOTH blowing and vacuum
That's a blower with vacuum capability, not a dedicated vacuum pump. → See our Roots Blower Vacuum Pump or contact us for guidance.
You need oil-free, high-vacuum for a pharmaceutical cleanroom
This typically calls for a dry screw or scroll pump, which we can source. → Contact us with your requirements.
Frequently Asked Questions
What is the purpose of a liquid ring vacuum pump?
The purpose of a liquid ring vacuum pump is to generate vacuum in processes where the gas stream is wet, corrosive, dirty, or potentially flammable — conditions that would rapidly degrade or create a safety hazard in an oil-sealed or dry pump. The water ring simultaneously seals, cools, and scrubs the gas. This makes liquid ring pumps the standard choice for chemical processing, pharmaceutical manufacturing, paper dewatering, mining filtration, and power plant condenser evacuation.
What is a liquid ring vacuum pump?
A liquid ring vacuum pump (also called a water ring vacuum pump) is a positive displacement vacuum pump that uses a rotating liquid ring — typically water — as the sealing, cooling, and contaminant-removal medium. An eccentrically mounted impeller spins inside a partially liquid-filled housing. As it rotates, the liquid forms a ring against the housing wall, and the changing volume between impeller blades and the liquid ring creates the pumping action. Because there's no metal-to-metal contact in the compression chamber, the pump tolerates gas streams that would destroy other vacuum pump types.
What is a rotary vane vacuum pump?
A rotary vane vacuum pump is an oil-sealed positive displacement vacuum pump. A cylindrical rotor with spring-loaded sliding vanes rotates off-center inside a circular housing. Oil seals the clearance between vane tips and housing wall, lubricates the sliding surfaces, and carries away compression heat. It's the most common industrial high-vacuum pump type, capable of reaching ~0.5 mbar (single-stage) or ~0.005 mbar (two-stage).
How does a rotary vane vacuum pump work?
A rotor with sliding vanes rotates off-center inside a housing. As it turns, the volume trapped between two adjacent vanes expands on the inlet side (drawing gas in), then contracts as the rotor carries it toward the exhaust side (compressing the gas). At the exhaust port, the compressed gas pushes past an oil-sealed valve and exits. Oil is continuously metered into the chamber and recovered through an exhaust separator. A gas ballast valve admits a small amount of air to prevent water vapor from condensing in the oil.
How does a liquid ring vacuum pump work?
An eccentrically mounted impeller spins inside a housing partially filled with water. Centrifugal force throws the water outward, forming a ring that follows the housing wall. Because the impeller is off-center, the water ring depth varies around the circumference. Gas enters where the water ring is shallow (large volume between blades), gets compressed as the water ring deepens (shrinking volume), and exits at the discharge port. The water simultaneously seals against gas leakage, absorbs compression heat, and scrubs out contaminants.
What are the applications of rotary vane vacuum pumps?
Rotary vane vacuum pump uses include: vacuum packaging (food pouches, meat trays, ready-meal containers), medical and dental suction systems, printing press sheet feeding, refrigeration and HVAC line evacuation, vacuum lifting and pick-and-place, laboratory vacuum, and vacuum hold-down for CNC and fabrication.
What are the applications of liquid ring vacuum pumps?
Liquid ring vacuum pump applications include: chemical process vacuum (distillation, solvent recovery, reactor evacuation), pharmaceutical manufacturing (vacuum drying, solvent stripping), paper machine dewatering, mining and mineral filtration, power plant condenser air extraction, and food processing (vacuum cooling, evaporation, bulk packaging).