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How a diaphragm vacuum pump works

The functioning of a diaphragm vacuum pump is based on the principle of a piston pump. In this case, medium is sucked in by moving a piston and opening the inlet valve or expelled by opening a second valve. In a diaphragm pump, however, a diaphragm is used instead of the piston and can be moved mechanically, pneumatically, electromagnetically or hydraulically.

Advantages of diaphragm vacuum pumps

By using the diaphragm, the drive is separated from the medium to be pumped. This prevents impurities from the pumped medium, such as liquids containing particles, from entering the drive. A diaphragm vacuum pump is therefore characterised by a particularly long service life and is also quiet and low-maintenance.

Diaphragm pumps in the laboratory

In the laboratory, diaphragm pumps are mainly used to achieve a vacuum. They are particularly suitable for this purpose, as no oil is required for the diaphragm and thus an oil-free vacuum can be guaranteed. These types of laboratory pumps are often used for the standard procedure of achieving a coarse or fine vacuum down to 0.5 mbar.

Applications for the diaphragm vacuum pump in laboratory and industry

Due to its insensitivity, the diaphragm pump has established itself especially in an environment where aggressive substances are used. Thus, a diaphragm vacuum pump can be used in the laboratory as well as in an industrial environment. Typical applications are:

  • evacuation of laboratory equipment such as rotary evaporators,
  • as a backing pump for achieving high vacuum in analytical instruments such as electron microscopes or also
  • for leak detection.

In addition to achieving a stable vacuum, the aim can also be to generate compressed air.

Furthermore, degassing, support of distillation processes and filtration processes as well as the drying of moist substances are among the application areas of the pump. The areas of application are widely spread over numerous industries and include the chemical industry and physical applications as well as the electronics or food industry.

Diaphragm vacuum pumps – design variants and technical differences

Due to the different areas of application and tasks, there are various design variants. Diaphragm vacuum pumps differ, among other things, in their delivery capacity and the vacuum to be achieved as well as in their chemical and physical resistance.

Flow rate

Diaphragm vacuum pumps can vary in their delivery rate. The transported quantity of the pumping medium is mainly defined by the mechanism of the diaphragm deflection.

The pumps at vary in their flow rate between 0.36m3/h, as with the KNF LABOPORT Mini Diaphragm Vacuum Pump N 86, and up to 3.6m3/h, as with the KNF LABOPORT Chemically Resistant Diaphragm Vacuum Pump N 840.1.2 FT.18. In most cases, a high flow rate is also associated with higher energy consumption. With some models, the delivery rate can also be selected in various stages.

Ultimate vacuum

The final vacuum to be achieved is also a decisive distinguishing feature. Depending on the application, it may be necessary to achieve a particularly fine vacuum. The ultimate vacuum is defined by the mechanism of the diaphragm deflection and by the diaphragm material. The AP 30 diaphragm vacuum pump, which you can also find in our online range, can achieve an ultimate vacuum of 100 mbar.

Chemical resistance

The chemical resistance of the diaphragm vacuum pumps is mainly defined by the materials chosen for the diaphragm and the valve seals. For example, particularly chemical-resistant materials such as fluorocarbon rubber are used for the seals. An example of a corresponding product from our portfolio is the diaphragm vacuum pump N 840.3 FT.18 from KNF.

Dimensions and weight

Diaphragm vacuum pumps also differ in their dimensions and weight. This can be decisive if laboratory pumps are to be used in laboratory fume cup boards, for example.

Small and light pumps, such as the KNF LABOPORT Mini Diaphragm Vacuum Pumps N 811, are handy and very flexible to use. Stable and larger pumps, such as the KNF diaphragm vacuum pumps N 145.1.2, are often more powerful and stable.

Diaphragm vacuum pump accessories

Numerous accessories are available for the individual diaphragm vacuum pumps, with which you can optimally adapt your pump to your requirements. Among others, you can choose from the following accessories:
Flanges & Connections:
With various flanges and connections you can ensure that your vacuum pump is always optimally connected to the vessel to be evacuated.

Hoses: At,hoses are available in various diameters and materials.

Fault plates and noise dampers: With special fault plates and additional accessories for noise damping, you can ensure that your pump stands securely and that the pumping process is quiet.

Valves: Special control valves allow precise adjustment of your desired vacuum.

You cannot find what you are looking for? Contact our service and we will help you quickly!

Top manufacturers in the range

At you can choose from a wide range of high-quality diaphragm vacuum pumps. We currently carry pumps from the following brand manufacturers:

KNF Neuberger

The family-owned company from Freiburg im Breisgau has established itself as one of the leading suppliers in the field of diaphragm pumps. Since 1946, the company has grown steadily and, with 17 locations, is now a global player with worldwide delivery. In our online portfolio, you can purchase a range of high-quality and reliable pumps from the manufacturer.


Laboratory instruments and vacuum pumps from the IKA Group are distinguished by their high quality and exceptional functionality. Since 1910, the company with its 900 employees has achieved one of the leading positions on the international market. With eight locations on four continents, the IKA Group supplies its products worldwide.


Phoenix Instruments GmbH is still a young company. Since its foundation in 2010, the small company has been offering laboratory instruments with high quality standards at a reasonable price and with excellent service. We also carry some high-quality pumps from this manufacturer at

Buy diaphragm vacuum pump at now for a free consultation

If you would like to buy a diaphragm vacuum pump to bring your laboratory up to the latest technical standard, we are at your disposal with excellent and competent advice. Contact us and our experts will ensure that you get the best equipment for your needs. You can reach us by phone on +49 30 209 657 900 or email us at [email protected]