Sarwat Engineering Company

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Industrial screw vacuum pumps


S-Series Air Map

Air Map

S-VSI Air Map
Low maintenance dry technology

Low maintenance dry technology

The contact free screw vacuum pumps of the Elmo Rietschle S-Series require no lubrication in the pumping chamber. This means our screw technology provides zero process contamination and no pollution caused by the pump operation.

Rugged and durable design

In the pump housing, two parallel screw rotors, both timing gear synchronized, turn in opposite directions. Gas is compressed in the direction of the discharge port. Gearbox and mechanical seals are oil lubricated. Cooling is achieved through the continuous flow of coolant through the pump housing.
Our dry running screw vacuum pumps feature high vapor and liquid tolerance, are easy to service and have a long service life – the low rotational speed ensures low noise and low vibration operation.

Multiple Applications for Screw Technology

Multiple applications

Elmo Rietschle screw vacuum pumps are primarily used in industrial applications across many different industries where clean, oil free vacuum is needed. They can also be combined with a vacuum booster in customized vacuum systems for very high suction capacities.General industrial applications such as packaging, drying and coating or vacuum furnaces are best served by our S-VSI range of pumps.

These sturdy vacuum pumps requiring little maintenance and service are dry running and offer remarkably low life cycle costs. Food packaging and processing are typical areas which benefit most from this machine – especially when it comes to oxygen applications.

Industrial vacuum applications for screw technologies

Parts Cleaning, Coating, Drying, Dust extraction systems, Industrial furnaces and  Vacuum metallurgy.

Plus applications in the packaging industry, Laboratories, solar technology and surface technology and electronics.

Food Packaging and Processing

Tray sealing, MAP packaging,Degassing, Drying, Tumbling, Cutting, Mixing and Cooling.

Screw Vacuum Pump Basic Operating Principle

Screw Vacuum Pump Basic Operating Principle

A screw vacuum pump consists of two parallel, screw-shaped rotors, one with a right-hand thread and the other with a left-hand thread. Both screws turn in the compressor housing without friction and at very tight clearances.

They are synchronized via a precision gear. The compression housing and the special shape of the screws form the compression chambers. Due to the opposite rotation of both screws the chamber connected with the suction port is enlarged and the gas is transported into the compression chamber. Then the chamber moves axially from the suction side to the pressure side (arrow).

In variable pitch models, the gas is compressed at each pitch change and cooled before the next pitch change, resulting in greater efficiency. On the pressure side the chamber is moved against the axial housing wall and the volume is reduced until the front surface of the screw opens the pressure channel and the pre-compressed gas is discharged through the pressure connection. Cooling is achieved using a water cooled outer chamber. For some pump sizes additional cooling gas can be introduced into the pump.

Screw vacuum pump operating principles cut section model

Wide performance range

Wide performance range

Our S-VSI screw vacuum pumps achieve an ultimate vacuum of 0.08 mbar (abs.) and can operate at any pressure between end vacuum and atmospheric pressure.


S-VSI Screw Vacuum Pump Cut Section Model

The S-VSI screw vacuum pump (sizes 100 and 300) represents modern, state-of-the-art dry running vacuum technology that is not only extremely energy efficient and reliable but offers a low life cycle costs. It is used in a variety of industrial applications such as drying and packaging. 

Advantages at a glance

  • Dry running, contact free operation
  • High vacuum in one stage
  • Application specific options
  • High water vapor tolerance
  • Short evacuation time due to high suction capacities
  • Low noise level
  • Easy to service
  • Low life cycle costs
  • Oxygen version available

Dry running screw vacuum pump – S-VSI

S-VSI vacuum pumps


  • Dry running, contact-free screw vacuum pumps.
  • Long service intervals thanks to oil-free operation.
  • Low life cycle costs.
  • No need for expensive and frequent oil changes.
  • Low running temperature due to the progressive graduation of the screw pitch.
  • Especially suitable for industrial applications like packaging or drying processes.
  • Can shorten cycle times in packaging applications.
  • Volume flow 100 to 360 m³/hr
  • Volume flow 58.8 to 211.8 cfm
  • End vacuum 0.1 mbar (abs)