The new Varodry dry-compressing screw vacuum pump, made by Leybold, Cologne, Germany, is 100% oil-free. Screw pumps are considered state-of-the-art industrial vacuum pumps, according to company officials, and the Varodry series is well suited for a wide range of manufacturing processes. That’s because in industrial settings, pumps not only need to handle clean air, but also dirt, particles, outgassing of media and vapors. Processes may not be stable, but involve various disturbance factors. The pump must be able to tolerate all of this. In general, screw pumps are the best choice for such demanding requirements, said the company.
The pump is currently available in sizes VD65 (65 m³/hr) and VD100 (100 m³/hr), and sizes VD160 and VD200 will be added shortly. The Varodry reportedly offers a number of advantages over conventional screw-pumps. One important feature is its integrated silencer that lets the pump offer a quiet and pleasant sound profile. Another factor which makes a significant contribution to improving production processes includes a variable-inlet flange arrangement, which enables a flexible installation of the pump within the plant. Further, the design of the silencer without sponge-like damper materials and the exhaust flange located at the lowest point of the pump facilitates pushing-out liquids or condensed vapors. This prevents potential formation of rust and contributes significantly to process reliability.
A further advantage is the reliability and efficiency of the pump. It can operate continuously at any inlet pressure and fully resists repeated shock venting. Any number of cycles can be run without overload, which is still not the standard for other pumps on the market.
A major differentiator of the Varodry is that it is completely oil-free. Other screw-type vacuum pumps may be dry compressing; nevertheless, all these pumps have gear compartments partly filled with oil to lubricate the bearings and gears.
This is not the case with Varodry pumps: the unit is 100% oil-free. Thus, there is no chance for oil migration from the gear chamber into the compression chamber where this oil might react with pumped gases or, in worst case, migrate backwards to the process chamber.
That’s not a problem with the Varodry, as it uses grease-lubricated bearings rather than oil-lubricated gears. Drive and synchronization is via a high-tech tooth-belt which, if necessary, can be replaced by the operator in just a few minutes. This also eliminates the gear oil exchanges which are required by other types of screw pumps. It is therefore impossible for any oil to migrate backwards into the process chamber and get blown out of the exhaust or leak on the floor during gear-box maintenance. The Varodry is therefore the first pump on the market which is 100% oil-free, and that can have a significant impact on cost reduction and process cleanliness.
Another technical advantage for industrial users is air cooling of the pump. This simplifies the integration of the pump into the plant, as there is no need for plumbing a sometimes-complicated water supply.
In contrast to most competitor products, the Varodry has a moderate temperature profile. The low internal temperatures peak at around 100° to 130° C (212° to 266° F) depending on the operation point. That permits handling of temperature sensitive media which otherwise could react and build up contamination inside the pump. Operating at moderate temperatures is optimal for many applications, enabling extended operation without need for compression-room cleaning.
These properties qualify the product for a number of applications:
Drying processes and industrial cleaning. Products like cast machine parts must be dried thoroughly after cleaning to avoid immediate flash rust corrosion. The best method to dry such massive parts, which can have hidden solvent reservoirs inside bore-holes or cavities, is vacuum drying. Moisture is extracted from even the smallest holes and the part is completely dried. This requires pumps that can tolerate a lot of vapors.
Regeneration. The same holds for successful cryopump regeneration. Cryopumps freeze gases and require a regular regeneration, during which the pump is heated, and the stored gas is released and must be pumped out. Large quantities of water form during this process.
Protective coating. Optical coatings such as on corrective lenses, or decorative coatings, say for bathroom fittings, usually produce dust in the sputtering process. A dry compressing screw-pump simply blows such dust through while in oil-sealed pumps the dust is trapped which causes excessive wear of the motive parts.
Freeze drying. In addition to drying processes in industrial cleaning systems, the Varodry is also used in food-related freeze drying applications, as well in pharmaceutical production. Drying applications are also necessary when manufacturing lithium-ion batteries and power-storage devices.
Vacuum drying. Another target market which involves vacuum drying is the manufacture of transformers and other high-voltage transmission components. Such components contain insulation materials, like paper windings, which must be absolutely dry. Under vacuum, moisture in the insulation is reduced to only a few ppm. Water-vapor compatibility is also critical.
Degassing. In composites applications, degassing is essential to ensure the resin is bubble-free prior to use. And during infiltration the resin is pulled into the pre-evacuated fiber material. In both process steps, the resin is outgassing and vapors enter the pump, which must be built to tolerate this and permit trouble-free operation.
Plasma cleaning. Besides liquid, gaseous and solid, plasma is the fourth state of aggregation. Typical plasma applications are surface cleaning and activation or sterilization where bacteria are killed by the hot surface plasma without a real heat-load for heat-sensitive products. In plasma applications, pressure is typically reduced to <1 mbar, a reactive gas as O2 or H2O2 is introduced, and then the plasma is ignited. Pumps must handle the plasma-gases plus the burnt by-products. Plasma processes are complicated, which makes it difficult to define exactly the gases the pump must handle. A robust, dry pump is therefore ideal in these applications because it can convey nearly all substances without trouble.
In all these applications, the attributes make the Varodry a good alternative to the typical pumps on the market.