Pfeiffer Rotary Vane Pumps

Pfeiffer rotary vane pumps are dependable, oil-sealed workhorses for laboratories, analytical instruments, industrial systems and backing duty. The two-stage DUO series reaches a low ultimate pressure in a compact package, while the single-stage UNO series offers robust performance for higher-pressure applications. At Provac Sales, we supply new and rebuilt Pfeiffer DUO and UNO pumps and repair both series in house.

Pfeiffer Vane Pump Models We Carry

Our Pfeiffer rotary vane collection includes:

• Pfeiffer DUO 1.6M
• Pfeiffer DUO 2.5, rebuilt
• Pfeiffer DUO 3 and DUO 3M
• Pfeiffer DUO 5, rebuilt, and DUO 5M
• Pfeiffer DUO 6M
• Pfeiffer DUO 10M and DUO 11M
• Pfeiffer DUO 20M
• Pfeiffer UNO 6 and UNO 6M

The number in each model name reflects the approximate nominal pumping speed in cubic metres per hour. The M suffix on many current DUO models indicates a magnetically coupled drive, which removes the traditional shaft seal and reduces the risk of oil leaks. Listings show the motor, voltage and condition for each unit.

DUO vs UNO: Which Do You Need?

DUO pumps are two-stage, which means they reach a much lower ultimate pressure. They are the standard choice for turbo backing, analytical instruments and most lab work.

UNO pumps are single-stage, which gives a higher ultimate pressure but makes them well suited to applications that run at higher pressures or pump larger amounts of gas, such as some drying, packaging and industrial tasks.

If you are replacing an existing pump, match the same series and size where possible.

How a Rotary Vane Pump Works

A rotary vane pump has an off-center rotor inside a cylindrical stator. Vanes slide in slots in the rotor and press against the stator wall. As the rotor turns, the vanes trap gas, compress it and push it out through an exhaust valve. Oil seals the clearances, lubricates the moving parts and carries away heat. In a two-stage DUO pump, the first stage exhausts into the second, allowing a lower ultimate pressure.

How to Choose a Pfeiffer Vane Pump

Consider these factors:

• Required pumping speed and the volume of your chamber or instrument
• Ultimate pressure needed
• Whether the pump will back a Pfeiffer turbo pump
• Vapors or solvents in the process, which call for gas ballast and suitable oil
• Electrical supply, including voltage, phase and frequency
• Inlet and exhaust flanges, typically DN 16 or DN 25 ISO-KF
• Exhaust filtration with an oil mist filter
• Whether a magnetically coupled M version is preferred to reduce leak risk

Applications for Pfeiffer Vane Pumps

Pfeiffer DUO and UNO pumps are used in:

• Backing turbo pumps in pumping stations and custom systems
• Mass spectrometers, electron microscopes and analytical instruments
• Helium leak detectors
• Freeze drying, vacuum ovens and degassing
• Laboratory filtration and distillation
• Vacuum coating and small furnaces
• Refrigeration and HVAC service
• Vacuum packaging and industrial processes

For higher speed in the medium vacuum range, add a Pfeiffer Okta Roots booster.

Gas Ballast and Pumping Vapors

When a vane pump compresses gas containing water vapor or solvents, the vapor can condense into the oil, reducing performance. The gas ballast valve on DUO and UNO pumps admits a small amount of air into the compression stage to keep vapors from condensing. Use gas ballast when pumping vapors, and run the pump with the ballast open after the process to clear the oil. For heavy solvent loads, add a cold trap before the pump.

Maintenance Tips

• Check oil level and color through the sight glass regularly
• Change oil at regular intervals, more often in dirty or vapor-heavy processes
• Use the correct pump oil from our vacuum fluids and greases collection
• Fit and maintain an exhaust oil mist filter
• Watch for rising ultimate pressure, noise or oil leaks
• Avoid running with a blocked exhaust

DUO Pumps vs Oil-Free Alternatives

A DUO pump costs less to buy than most oil-free pumps and reaches a lower ultimate pressure than diaphragm pumps. The trade-off is oil maintenance and the risk of oil back-streaming in clean systems. If your process cannot tolerate oil, consider a Pfeiffer HiScroll, MVP diaphragm pump or ACP dry pump.

New vs Rebuilt Pfeiffer Vane Pumps

Rebuilt DUO and UNO pumps are a cost-effective way to replace a worn pump in an existing instrument or station, keeping the same footprint, flanges and wiring. New pumps suit new installations and users who want the latest M versions. Each listing and quotation confirms the condition and warranty.

Pfeiffer Vane Pump Repair and Rebuild

Provac Sales repairs Pfeiffer DUO and UNO series rotary vane pumps, along with Alcatel A, C, C2, CP, CP+ and SD series pumps. A rebuild may include inspection, disassembly, cleaning, replacement of vanes, seals, gaskets, bearings and other worn parts, reassembly and vacuum performance testing.

Drain the oil before shipping, submit an RMA request and complete the contamination data sheet. See our pump repair page for more.

What to Send Us for a Fast Quote

• The DUO or UNO model and part number from the rating plate
• Motor voltage, phase and frequency
• Whether you need new or rebuilt
• The instrument or turbo pump it will back, if any
• Your process and any vapors being pumped
• Photos of the rating plate and connections

About Pfeiffer Vacuum

Pfeiffer Vacuum was founded in 1890 in Wetzlar, Germany, and is known as a pioneer of turbomolecular pump technology. In 2010 the company acquired Adixen, the former Alcatel Vacuum Technology business, which is why many Alcatel and Adixen designs now carry the Pfeiffer name. The DUO series has been part of Pfeiffer's range for decades and remains one of its best-known products.

Choosing Between Standard and M Versions

Older and some current DUO pumps use a conventional radial shaft seal, which is a wear item and a common source of oil leaks over time. M versions use a magnetic coupling instead, sealing the pump completely and removing that failure point. If you are replacing a pump that has repeatedly leaked at the shaft seal, an M version is often worth the upgrade.

Frequently Asked Questions

What does the M mean on a DUO 6M or DUO 10M?

The M indicates a magnetically coupled drive, which removes the dynamic shaft seal between motor and pump and reduces the risk of oil leaks.

Can a DUO pump back a HiPace turbo pump?

Yes. DUO pumps are a common backing choice for HiPace turbo pumps. Choose a size that holds the foreline below the turbo's maximum backing pressure.

Why is my Pfeiffer vane pump leaking oil?

Common causes include a worn shaft seal on older non-M versions, overfilling, a blocked exhaust filter or loose fittings. Check the exhaust filter first.

Is a rebuilt DUO 5 a good replacement for my old pump?

In most cases, yes. A rebuilt pump of the same model keeps the same connections and performance. Confirm that the motor and voltage match your installation.

Request a Quote on Pfeiffer Rotary Vane Pumps

Send us the model, motor voltage and phase, required condition and application. We will check inventory or quote a rebuild of your existing pump. Contact us or call 831-462-8900.