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An Introduction to Rotary Vane Vacuum Pumps

Rotary Vane Vacuum Pumps by Elmo Rietschle

What is a Rotary Vane Vacuum Pump?

A rotary vane vacuum pump in its simplest definition is a type of pump technology that enables the compression of air inside the pump chamber to create suction for the removal of air molecules from a vessel or area.

Rotary vane vacuum pump works on a positive-displacement pumping principle. The design consists of a rotor, which is mounted eccentrically inside a cylindrical housing or stator. Blades, mounted inside the rotor, move in and out due to centrifugal force following the internal surface of the housing. A more detailed description of the operating principle of an oil lubricated and a dry running rotary vane pump can be seen further in this article.

What Are Benefits of Using Rotary Vane Pumps?

Rotary vane vacuum pumps can either be oil-sealed or dry-running. Each type of vane pump offers distinct benefits, depending on the application. Benefits of rotary vane vacuum technologies include:

High end vacuum with one compressor unit
Blades with long service life
Optimised oil-water separation (oil lubricated only)
High water vapour tolerance, by gas ballast (oil lubricated only)
Low noise level
Low vibration, virtually pulsation free.
Easy to maintain
Suitable for a wide range of industrial applications
Completely oil-free (dry running rotary vane pumps only)

Oil-lubricated rotary vane vacuum pumps provide a number of benefits compared to other vacuum technologies:

Oil-Sealed - oil provides an effective seal enabling an ultimate vacuum up to <0,5 mbar (abs.)
Lubrication prevents wear - Aluminium blades, rotor, housing, and housing cover bearings are lubricated with oil making them virtually wear-free.
Reduced Operating Temperature - Heat is reduced as oil reduces friction with the compression chamber.
Corrosion protection - oil protects all components from corrosion and reaction with the gas
Cleaning effect - The oil cleans the compressor chamber of impurities and prevents damage extending pump life and performance.

VCS 200 VCS 300 Rotary Vane Vacuum Pump from Elmo Rietschle

VCS Oil-Lubricated Rotary Vane Pump by Elmo Rietschle

Types of Rotary Vane Pumps

Common types of vane pumps include oil-sealed or dry-running pumps. Every rotary vane vacuum pump is based on the same standard components. Depending on the design, size or model, there will be variations in components.

Blades ("vanes")	Motor
Rotor	Oil Separator Housing
Cylindrical Housing	Oil / Oil Sump
Suction Flange	Filters
Non-Return Valve	Float Valve

Oil-Sealed Rotary Vane Vacuum Pumps

Dry Running Rotary Vane Vacuum Pumps

Applications For Vane Pumps

Oil-lubricated rotary vane pumps find diverse applications across various industries. In chemical and pharmaceutical processes, they are instrumental in processes such as crystallization, degassing, distillation, drying, evaporation, fractionation, impregnation, supercooling, and vacuum coating through sublimation. Additionally, they play a crucial role in vacuum filtration and environmental engineering processes like aeration and dust extraction systems. In the realm of food processing, vane pumps are integrated into bottling and filling machines, and cutting machines, ensuring efficient industrial operations. Similarly, in industrial applications, they are vital components in drying systems, dust extraction systems, industrial furnaces, and vacuum hold-down mechanisms. The packaging industry benefits from rotary vane technology through centralized vacuum systems, packaging machines, and pneumatic conveying systems. Lastly, in the woodworking industry, the vanes are essential for dust extraction systems and vacuum hold-down mechanisms, contributing to the efficiency of woodworking processes.

Dry running rotary vane pumps play a pivotal role in several industries, demonstrating their versatility and efficiency. In the field of environmental engineering, these pumps are utilized for aeration processes, ensuring the effective oxygenation of various environmental systems. In industrial applications, they are indispensable for tasks such as lifting and holding objects, as well as facilitating pick and place operations and streamlining production processes. Furthermore, rotary vane pumps are integral components in the packaging industry, powering packaging machines that are essential for the efficient packaging of products. In the printing industry, dry-running rotary vane pumps find their application in post-press operations, enhancing the quality and speed of printing presses. Additionally, in the woodworking industry, vane pumps are crucial for vacuum hold-down systems, securing materials in place during various woodworking processes, thereby ensuring precision and safety.

Operating Principle Of Rotary Vane Vacuum Pumps

Pressure increase by volume reduction is the principle behind rotary vane operation. The whole cylinder housing is wetted with a film of oil on which the blades run almost without any wear.
The oil lubrication is produced purely by the differential pressure of the housing and the oil separator housing. This is achieved through some oil pipes between the housings.
In a cylindrical housing, a rotor is positioned eccentrically so that it is on the top almost touching the cylinder housing. The blades are pressed on the wall of the housing by centrifugal force and generate three different chambers which capture the air.
When the first chamber is opened, the air flows through the suction flange into the compressor chamber.
While the rotor rotates, the next blade closes this chamber (and opens directly the next one) At this point the area between the blades has achieved its maximum air volume.
The oil gas mixture gets compressed by volume reduction and blows out into the oil separator housing.
Some pump models are fitted with outlet valves which stop the backflow of discharged air when the maximum pressure has been reached or the pump is switched off.
Oil is mechanically separated from the gas by the complex construction of the oil separator housing. Oil is collected in the oil sump. This process removes 95-98% of the oil content in the air.
The remaining oil gas mixture is then taken through fine filter elements which removes the remaining small oil particles. These oil particles will be reintroduced through a float valve into the pump‘s oil circuit.
Virtually oil-free gas can either be blown out through the air outlet or through hoses or pipes.