Technology
Rotary piston vacuum pumps
Oil-sealed, slow-running vacuum pumps in robust cast construction – for harsh processes down into the medium vacuum range. 4 current models from Atlas Copco and Edwards – comparable by pumping speed and rated motor power.
Compare 4 modelsHow the technology works
- 4models
- 2series
- 2manufacturers
- 0.033 mbarlowest ultimate pressure
Touch the points: the parts explain themselves.
Manufacturers and series
Manufacturers and series
Each series leads to its page with all models. “Show only …” sets the filter of the product overview.
Atlas Copco
2 models · 234–442 m³/h
Edwards
2 models · 234–442 m³/h
Product overview
Compare all 4 models
The filters on the left narrow down the selection by the key figures of the models – for 50 or 60 Hz.
Atlas Copco GLS series 2 models
Edwards Stokes Microvac series 2 models
Edwards Stokes Microvac 212JPumping speed 234 m³/h 50 Hz234 m³/h 60 HzUltimate pressure 0.033 mbarRated motor power Variants 8Edwards Stokes Microvac 412JPumping speed 442 m³/h 50 Hz442 m³/h 60 HzUltimate pressure 0.033 mbarRated motor power Variants 13No model matches these filters.
Atlas Copco GLS series 2 models
Edwards Stokes Microvac series 2 models
Models that a manufacturer no longer carries in its current range are not part of this overview; they are listed in the manufacturer’s “Outdated models” section.
Operating principle
How a rotary piston vacuum pump works
An eccentric on the shaft guides the piston on a circular path through the cylinder; as it moves, the piston runs closely along the cylinder wall. Its hollow slide valve slides in a rotatable guide and lets the gas flow into the space behind the piston. In front of the piston the gas is compressed and expelled through the outlet valve. Oil seals the gaps and lubricates.
The drawing shows the basic principle. The designs of the individual manufacturers differ in detail.
- SuctionThrough the hollow slide valve (B) the gas flows into the space behind the piston (C); this space grows with the rotation.
- CompressionAfter one revolution this space is cut off from the inlet. The piston now pushes the gas ahead of it and compresses it (E).
- DischargeThe compressed gas leaves the pump through the outlet valve (F).
Key figures
The technology in figures
The ranges result from the current models in our range.
Pumping speed (50 Hz)
234 to 442 m³/hin our range
Rated motor power (50 Hz)
5.5 to 11 kWin our range
Ultimate pressure compared (mbar, logarithmic)
For comparison: the oil-lubricated rotary vane vacuum pumps in our range reach 1 × 10⁻³ to 20 mbar.
What characterises the technology
Oil-sealed
Oil seals the gaps and lubricates. Bearings and sealing surfaces are lubricated automatically.
Low speed
The pumps run at around 500 revolutions per minute – this ensures a long service life.
Robust design
Cast construction with few moving parts and large clearances.
Gas ballast
The standard gas ballast counteracts the condensation of water vapour in the pump.
Advantages
What speaks for this technology
- Robust cast construction
- Few moving parts, large clearances
- Low speed, long service life
- Automatic lubrication
- Gas ballast as standard
- Can be serviced on site
Applications
Where they work
- Metallurgyvacuum melting, heat treatment
- Coatingvacuum coating
- Dryingtransformer drying
- Chemicals and pharmaceuticalschemical processing, pharmaceuticals, PET processing
- Automotive and aviation industries
- Leak detection
Frequently asked questions
Questions about rotary piston vacuum pumps
How does a rotary piston vacuum pump work?
An eccentric guides the piston on a circular path through the cylinder. Through the hollow slide valve of the piston the gas flows into the space behind the piston; in front of the piston it is compressed and expelled through the outlet valve. Oil seals and lubricates. The drawing in the section Operating principle shows every step.
What ultimate pressure do rotary piston vacuum pumps reach?
The models in our range reach ultimate pressures from 0.033 mbar. Together with a Roots vacuum pump connected upstream, lower pressures are possible.
Which gases are rotary piston vacuum pumps permitted to pump?
That depends on the model. Edwards, for example, approves the Stokes Microvac pumps only for air, nitrogen and other inert gases. The application limits are given on the product page of the respective model.
From which manufacturers does Ehrler & Beck carry this technology?
Currently from Atlas Copco and Edwards. The series are listed in the section Manufacturers and series.
How do I find the right model?
In the product overview, the filters narrow down the selection by the key figures of the models. For sizing, it is best to tell us the gas to be conveyed, the working pressure and the flow rate you need – we will be glad to advise you.
What do the figures for 50 Hz and 60 Hz mean?
Flow rate and rated motor power depend on the mains frequency. The overview therefore shows both values wherever the manufacturer states them, and the size filters can be switched between 50 Hz and 60 Hz.
Does Ehrler & Beck also supply spare parts and service?
Yes. Ehrler & Beck offers original spare parts and accessories as well as maintenance and repair.
Which model fits your process?
Tell us the gas to be conveyed, the working pressure and the flow rate you need – we will advise you on selection, spare parts and service.
