Diaphragm Liquid Pump Technology As the Basis for Reliable Ink Supply

At KNF, the development of a new diaphragm liquid pump starts with looking at the end of the value chain. The inkjet market is a good example. What began several decades ago with digitally printing ink on paper, gradually evolved into an innovative and expanding industry. The advantages of digital inkjet printing combined with diaphragm liquid pumps are also being used in different areas of application: textile and packaging industry, printing on ceramics and glass products, electronics industry and, more recently, additive manufacturing.

The KNF FP 150 is part of the smooth flow pump series.
The KNF FP 150 is part of the smooth flow pump series.

All of these applications have one thing in common: they require fluids such as primers, inks, varnishes, resins, coatings or even electrically conductive liquids to be available at the print head in the right quantity, at the right time - and without compromising the quality of the fluid. KNF diaphragm liquid pumps are ideal for these applications for two reasons: Firstly, they handle fluids very gently, ensuring that their specific characteristics do not change. Secondly, they can easily handle chemically aggressive or abrasive media such as ink containing particles. This is important in terms of service life and reliability of a printing system using ink pumps.

One of the few arguments which might be used against the typical diaphragm pump is the relatively high pump pulsation due to its mode of operation. This causes resistance in the hoses, some of which are only a few millimetres in diameter and can be several meters long - reducing the efficiency of the pumping process of a diaphragm liquid pump. In the worst case, pressure peaks in the ink pump system also affect the quality of the print because they can disrupt the precisely controlled pressure conditions within the print head. In connection with the increasing demand for larger quantities of ink and higher viscosities, pulsation is becoming increasingly noticeable.  KNF has developed a new generation of products to address these inherent issues without compromising the fundamental benefits of the typical KNF diaphragm pump.

Our KNF Smooth Flow Promise

Following the trend towards higher ink volumes, KNF started the development of smooth flow pumps several years ago. Some of these ink pump models, have been successfully established in the printing markets. Thanks to very low pump pulsation, they enable an efficient and gentle flow of high liquid volumes. Learn more about the KNF smooth flow pumps. The exploded view image shows the features of the KNF FP 150 as part of the smooth flow pump series.

5-diaphragm technology
Wobbling eccentric
Integrated BLDC motor
5-diaphragm technology
By interlacing the flow and the pulses generated by each of the 5 diaphragms, a very high and yet smooth flow is achieved in the diaphragm liquid pump. This helps to efficiently transfer liquids through long tubing with smaller diameters, since smooth flow pumps reduce pressure loss. It also minimises vibration of the tubes, which can be bothersome to the printing process. (Featured product: KNF FP 150)
Wobbling eccentric
At speeds of up to 4,000 rpm, the wobbling eccentric transforms rotational movement of the motor to linear motion needed to drive the diaphragms. All this with generating almost no vibration and noise, and with only minimal forces acting on the motor hardware. This ensures a long, maintenance-free and highly reliable performance of the diaphragm liquid pump in the customer’s system. (Featured product: KNF FP 150)
Integrated BLDC motor
An integrated IP65 brushless DC motor allows for the precise adjustment of the smooth flow FP 150 between 0.2-1.5 l/min. The advantages of BLDC motors in smooth flow pumps include maintenance free drives, a long service life, and quiet operation with minimal vibration. (Featured product: KNF FP 150)




The KNF FP and FK pump series significantly reduce pulsation compared to typical single-headed pumps, making them a valid replacement for gear pumps.
KNF specialises in tailor-made solutions which allows us to focus on the diaphragm liquid pump features that are most beneficial and important to you. Contact us today to learn more about all available options.
KNF FP and FK range pumps offer high flow rates in a compact size, providing great installation and application flexibility.
FP Series
  • Our low pulsation pump products
  • Flow rates up to 5 l/min 
FK Series
  • KNF's highest flow liquid pump  
  • Liquid flow rates over 12 l/min
  • External pulsation dampeners
  • Pressure control valves
  • Filters
  • Compact
  • High performance to size ratio
  • Long life
  • Maintenance-free
  • Self-priming
  • Can run dry
  • Versions available for agressive media
  • NSF-certified options for food grade requirements
  • Excellent flow controllability
  • Lightweight
  • High IP protection class options available (up to 65)
Inkjet Printing
  • UV, water-based, solvent ink recirculation to prevent pigment settling
  • Ink temperature management
  • Glaze, varnish, binder and hot-melt recirculation
Analytical Instruments
  • Precise and flexible transfer of reagents with excellent linearity and turn-down ratio
  • Delivering of solvents during sample preparation
  • Dispensing cleaning agents for needle washing
  • Patient temperature management
  • Aesthetic laser cooling systems

A Closer Look at Smooth Flow Pumps

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Liquid Transfer With Low Pressure Pulsation

Liquid Transfer With Low Pressure Pulsation

In some applications, flow or pressure pump pulsation may cause serious issues such as ink foaming and ink starvation. Therefore, the new KNF FP series of smooth flow pumps was designed to provide a much smoother flow delivery.

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From Prototyping to Mass Production

From Prototyping to Mass Production

Manufacturers of 3D printing hardware can rely on KNF ink pumps as metal binder jetting becomes a ready-for-production process. The newly developed FP and FK series of low pulsation diaphragm liquid pumps are made to meet the requirements of the 3D printing industry.

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Demands for High-Quality Printing

Demands for High-Quality Printing

The high-quality standards in inkjet printing require a smooth and reliable ink flow. Low pump pulsation is necessary to avoid undesirable pressure fluctuations. Facing the demand for high-quality results, KNF engineers have closely worked with industry experts to develop low pulsation pumps.

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Get To Know the KNF Smooth Flow Pump Series

Would you like to know more about smooth flow pumps? Visit our product overview and find the pump for your specifications and requirements.

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