Displacement Pumps Anyone Can Do “Simple”: Why You Should Consider Displacement Pumps

Author / Editor: Dominik Stephan* / Dominik Stephan

Have centrifugal pumps reached their limits? When is it worthwhile considering displacement pumps — Pump expertise for chemical and food processes: When centrifugal pumps reach their limits, it is time for displacement pumps. Whether as eccentric or screw spindle pumps — particularly for challenging media or in hygienic processes, it is worth taking your pump considerations a step further.

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From food to chemistry: With pumps, such as the Twin NG hygienic progressing cavity pump, Wangen positions itself as a specialist for demanding conveying tasks.
From food to chemistry: With pumps, such as the Twin NG hygienic progressing cavity pump, Wangen positions itself as a specialist for demanding conveying tasks.
(Source: Pumpenfabrik Wangen, ©Ramil Gibadullin, Syda Productions - stock.adobe.com; [M]EHaselmann)

Used oil, paper pulp, adhesives, creams, soaps and shampoo — despite their differences, these materials all have something in common: They are a real challenge for the pumping/conveying systems used. Tough, sticky and with high viscosity, these media are difficult for centrifugal pumps to handle — yet, these still account for over two thirds of the units installed in the chemical industry. But there is more: Many sensitive media need to be pumped with low pulsations, under stable pressure and with precise dosages to ensure product quality. And, for applications in cosmetics, pharmaceuticals or the food industry, there are strict hygiene requirements on top of this. But it is also possible to do things differently.

If you need to pump difficult media with precise dosages, low pulsations and gently, then you should also have a think about displacement pumps. Eccentric pumps and screw spindle pumps offer significant advantages for a large number of applications. Particularly mixed media with gas, fluid and solid content, set or paste-like products with low to very high viscosity with constant delivery rates and fluctuating pressures can be pumped in a very well-controlled manner with almost no pulsations.

Polyol, isocyanate, PVC compounds, surfactants, adhesives or galvanic slurries: The German pump experts understand the challenges faced by their customers — after all, the “pump factory” has five decades of experience in delivering solutions for pumping high-viscosity and difficult media. Since its beginning in 1969 with pumps for high-density solids and slurries in agricultural ­applications, Wangen has established itself as a reliable partner for the pumping of fluids in industry, infrastructure projects and agriculture — i.e. applications in which robustness, quality and reliability are the key to successful operations.

A Construction Kit Approach

Already in the early 1970s, industrial pumps such as the R80 hopper pump expanded the company’s range of solutions into the field of sewage technology and waste disposal — but also into the food industry, which represented a step forward in terms of hygiene considerations. This challenging industry quickly found a taste for the robust workhorses from Southern Germany — and wanted more: In 1980, chamber screw pumps for different types of fats were added to the company's product portfolio. In the same year, Wangen discovered the construction kit principle — way before the recent discussions of modular engineering — with its KL range of pumps. By locating the drive directly on the bearing block, the pump specialists managed to combine the trend for ever more bespoke solutions with the desire to be able to manufacture as much as possible in series production with consistent quality.

In the new millennium, the manufacturer added screw spindle pumps to its range of eccentric screws. The Wangen pumps Twin and Twin NG are particularly ideal for hygienic applications, where they enable gentle pumping thanks to their optimized and technically refined flow behavior, as well as thorough cleaning of the pump with CIP systems (clean-in-place). And the clever part is that after the product has been conveyed, the Twin pump can also pump the water or cleaning medium, which means that the user does not need a CIP return pump. According to the developers, not only does this save space and money, but it also ensures excellent cleaning results.

A Broad Portfolio of Displacement Pumps

Today, Wangen offers a wide portfolio of pumps for use in chemical and pharmaceutical engineering systems. The eccentric and screw spindle pumps can be matched to their particular task in terms of shape, materials and the specifically defined performance parameters, making them perfect for tasks in the chemical industry. The housings are flow-optimized, the media are pumped with almost zero pulsations, the dosage accuracy is high, the materials that can be used are FDA-approved on request, and the pumps are designed with no dead areas so that they can be cleaned effectively and quickly. The portfolio for special, hygienic applications has now been expanded and added to. Here, the main focus is on ease of servicing and problem-free use in chemical and industrial plants.

The “Hyline” series is also optimized for highest cleanliness and hygienic applications. Instead of the usual shaft drive, it uses a flexible connection, which consists of a criss-crossed rope made of spring steel that can be sheathed in various elastomers to suit the requirements of the application. “The shaft joint has the same diameter from the mechanical seal to the rotor, so it is ideal for cleaning and offers excellent flow properties,” explains Florian Biegger, pump designer at Wangen. “Thanks to the design of the drive train, there is no shaft interface in the product area that would require complicated sealing measures and would make it much more difficult to clean the pump.”

Another Piece of the Pumps-Puzzle

Since all good things come in threes, 2019 will see the addition of a further hygienic eccentric screw pump to the Wangen portfolio. According to CEO Markus Hofheinz, the MX, which was originally developed by Knoll Maschinenbau, is intended to round off the company's offering for pharmaceutical and food processes with Even Wall technology and hygienic basic design, combined with high surface requirements: “We are expanding our strong hygienic screw spindle sector with the leading hygienic eccentric screw pump and will be offering our customers a significantly wider range from a one-stop source.” Safe, reliable, clean and easy to service — these are all attributes of the new pump, Hofheinz says.

But the key feature of the MX is the design of the stator jacket as an Even Wall product, adapted to the contour of the rotor. The pump specialists explain that this offers numerous advantages over conventional designs with a cylindrical outer geometry of the stator jacket, with correspondingly different wall thicknesses of the elastomer. According to their claims, the MX offers significantly higher pressure stability, less backflow, longer service times, improved efficiency, reduced shearing forces acting on the product and better suction performance. And its output is impressive: Thanks to its enclosed chamber, the MX is claimed to supply pressure of at least 10 bar, whereas conventional eccentric screw pumps often fail to top more than around 4 to 6 bar.

Challenge? Accepted!

“We can look back with great satisfactions on the developments of our first 50 years. Wangen has continuously and successfully evolved from a niche provider in the agricultural sector to a global supplier of eccentric screw pumps and screw spindle pumps in various industry segments. Our engineering services, connected with our pursuit of quality and the high levels of commitment and dedication in all departments and from all our employees have made this growth possible and form the basis for continued success on the global market and in all the very different segments we operate in,” added the company’s board of management.