Molecular Drag Vacuum Pumps and Vacuum Generators
Last Updated: April 1, 2025
Description
Molecular drag vacuum pumps, also known as molecular pumps or drag pumps, are designed to create a vacuum by imparting a preferential motion to gas molecules. They achieve this by using a rotor drum with a ridged surface and a cylindrical stator. Vacuum generators, such as Venturi jet pumps, create a vacuum by utilizing the viscous properties of gases or fluids through a venturi chamber construction.
Working Principle
Molecular drag pumps operate by physically dragging gas molecules along the surface of a rotor drum, which has a ridged design. This mechanism allows the pump to create molecular flow through the system, achieving ultimate pressures as low as 10^-6 Torr. These pumps are particularly useful in systems with limited conductance and for operations that require frequent cycling. Venturi jet vacuum generators, on the other hand, create a vacuum by using a flow of compressed air, gas, or liquid as the motive fluid. The venturi effect in the chamber allows these generators to pull or create a vacuum without any moving parts, relying solely on the compressed fluid.
Applications
Molecular drag pumps are used in applications where there is a need for frequent cycling operations and where the system has limited conductance. Specific examples include laboratory settings where precise vacuum conditions are required for experiments. Venturi jet vacuum generators are often used in industrial applications where a simple and reliable vacuum source is needed, such as in pneumatic conveying systems or in processes where the absence of moving parts is advantageous for maintenance and reliability.
Advantages over other Vacuum Pumps and Vacuum Generators
Molecular drag pumps have the advantage of starting to pump at inlet pressures several torr higher than turbomolecular pumps, and they do not require as low backing pressures for full operation. This makes them more versatile in certain applications. Additionally, they have much lower pumping speeds compared to turbomolecular pumps with the same inlet size, which can be beneficial in specific scenarios. Venturi jet vacuum generators offer the advantage of having no moving parts, which reduces maintenance needs and increases reliability. They also do not require additional power sources beyond the compressed fluid, making them energy-efficient.
Limitations
Molecular drag pumps are limited by their ultimate pressure capability, which is lower than that of turbomolecular pumps, reaching only as low as 10^-6 Torr. They also have lower pumping speeds compared to turbomolecular pumps of the same inlet size. Venturi jet vacuum generators are limited by the need for a continuous supply of compressed fluid, which can be a constraint in certain environments or applications.
Considerations
When considering molecular drag pumps, it is important to evaluate the initial costs, which may be higher due to the specialized design and materials. Operating expenses can vary depending on the frequency of use and the specific application requirements. Durability and maintenance costs are generally favorable due to the robust design, but replacement parts may be costly. For Venturi jet vacuum generators, the main considerations include the cost and availability of the compressed fluid, as well as the potential need for additional infrastructure to supply the fluid. The absence of moving parts generally results in lower maintenance costs and increased durability.
from Edwards Vacuum
The new compact EPX180 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX180 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The new compact EPX180 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX180 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The new compact EPX180 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX180 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice. Compact series allow for dry backing pumps [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The new compact EPX500 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX500 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The new compact EPX500 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX500 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The new compact EPX500 high vacuum drypump offers enhanced performance with reduced cost of ownership. Using a unique patent protected mechanism the EPX500 is capable of pumping from atmosphere to ultimate pressures of <7 x 10-5 Torr. Based on the successful award winning IPX range, the modular... [See More]
- High Vacuum: Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: Mechanical; HighVac
- Application: Semiconductor
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
The EXT556H incorporates our hybrid bearing and enhanced molecular drag pumping technologies with turbomolecular pump stages on a single rotor. The result is a highly reliable pump well suited to applications requiring excellent light gas performance and ultimate pressures <10-10 mbar. With the... [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Ultrahigh Vacuum Applications
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
Edwards – world leader in vacuum technology – introduces the nEXT generation of turbomolecular pump. Built upon over a decade of experience with the tried and trusted EXT and STP ranges (with in excess of 200,000 units in the field), nEXT sets the new benchmark for scientific turbo... [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Scientific
from Drytek Distribution
These turbo pumps are ideal for economical standard applications requiring simple and reliable high vacuum. Features. Economical. Ceramic ball bearings. ISO/CF flange choice [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Industrial
from Edwards Vacuum
Edwards – world leader in vacuum technology – introduces the nEXT generation of turbomolecular pump. Built upon over a decade of experience with the tried and trusted EXT and STP ranges (with in excess of 200,000 units in the field), nEXT sets the new benchmark for scientific turbo... [See More]
- High Vacuum: Turbomolecular; Molecular Drag
- Configuration: Individual Vacuum Pump
- Vacuum Pump Type: HighVac
- Application: Scientific