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How Diaphragm Pumps Handle Demanding Media

The modular design of KNF diaphragm pumps ensures a highly reliable transfer of a variety of challenging liquids and gases

A safe transfer of fluids or gases is what any pump solution should aim for. From the chemical industry to food processing, there are many areas in which the pumps in use must not only be gas- and leak-tight or explosion-proof, but also capable of reliably transporting particularly demanding media like vaccines, inks, solvents or acids. The use of a diaphragm pump can be of decisive advantage when handling demanding media.

Demanding Media Require Special Systems

Diaphragm pumps are particularly suitable for applications relying on demanding media, as they offer distinct, design-related advantages over other pump types. The flexible diaphragm creates a seal between the inside of the pump and the atmosphere and prevents the transported media from coming into direct contact with its mechanical parts. Since they do not use dynamic seals, diaphragm pumps are also known as hermetic pumps.


The only components of the pump that the media come into direct contact with are the head plate, the intermediate plate, the diaphragm, the O-rings and the valves. Those wetted parts must be especially resistant to the medium the pump is designed to handle ‒ sometimes even against the atmosphere surrounding it. Optimizing this material mix can make the pumps resilient against corrosive and abrasive media.


The modular design of KNF diaphragm pumps allows for the use of a wide range of materials for each component, including aluminum, stainless steel, nickel-based alloy, PPS and PTFE for the pump heads. The elastomers of the diaphragms, O-rings and valves can also range from a variety of materials such as NBR, EPDM, FPM, FFPM or PTFE – making them suitable for media temperatures of up to 240° Celsius.

No Leaks, No Contamination: Keeping the Inside In and the Outside Out

An optimal mix of materials is also essential to ensure the highest possible leak-tightness. This is especially crucial for media that are very hazardous or expensive. Due to hydrogen’s explosive nature, for example, the gas-tight performance of every single KNF hydrogen pump is individually tested before delivery. Ensuring the overall tightness of the system is a key requirement for its explosion protection. Furthermore, individual parts of the pump can be insulated to prevent sparking or designed to keep potential sparks from being emitted into any surrounding explosive atmosphere.

Due to their high chemical resistance and long service life, N 680.1.2 Ex pumps are used in potentially explosive atmospheres.
Due to their high chemical resistance and long service life, N 680.1.2 Ex pumps are used in potentially explosive atmospheres.

Handle With Care: Ensuring Safe and Efficient Transfer of Abrasive and Shear Sensitive Media

Utilizing in-house developed BLDC technology – which is available for most KNF gas and liquid pumps – further opens up new optimization possibilities, including an even more precise control of the pump's performance. An advantage that allows the flow rate to be optimally matched to the fluid being handled and, combined with an optimized material mix, can help protect the pump's components from wear caused by larger abrasive particles.


Gentle handling may also be essential to ensure that the medium's overall structure remains unaffected during the transfer process. Diaphragm pumps are especially suitable for the transfer of shear sensitive media such as polymer solutions, biological materials or paints. The special Smooth Flow Technology of the KNF FK and FP series, for example, ensures that media requiring particularly careful treatment can be transported with caution and especially low pulsation. To maintain their individual properties without being damaged or degraded, Smooth Flow diaphragm pumps also prevent high-pressure peaks and negative pressures.

Smooth Flow Technology minimizes vibrations that could adversely affect the handled media.
Smooth Flow Technology minimizes vibrations that could adversely affect the handled media.

Maximizing Efficiency by Minimizing Maintenance

Because every application is different, KNF focuses on allowing for a high level of customization for the available pump solutions. The modular approach of KNF diaphragm pumps makes it particularly convenient to provide the ideal mix of several corrosion- and wear-resistant materials and to ensure a high leak tightness ‒ if needed, with explosion-proof certification like IECEx, ATEX, or NEC. Due to their availability in a wide range of sizes and configurations, and their ability to be additionally tailored with different drives and controllers, diaphragm pumps allow for a continuous and flawless performance and require especially low maintenance ‒ even with demanding media.

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