Knoll Maschinenbau GmbG

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Pumping Abrasive Media Economically: The MX in a Special Design

When it is necessary to transport abrasive media the pump can easily become a problem child: Abrasive fluids can lead to high wear and short lifetimes. A Portuguese paint manufacturer experienced this when he had to promote calcium carbonate. So he gave the MX-Pump from KNOLL Maschinenbau a try.

His demand: To pump 70% calcium carbonate in aqueous solution with a particle size of 6 microns at a pressure of 5 bars and to convey a capacity of 60 m³ / h. KNOLL provided him with a MX50 progressive cavity pump in special design: The stator is lined with a wear resistant elastomer, the rotor coated in special stainless steel (“ductile coated”). The universal joint also receives a sleeve in a wear resistant elastomer. Overall this MX-Pump appears as highly abrasion- and corrosion-resistant and therefor meets the high requirements of the chemical industry, especially when it comes to paints and coatings.

The result: After one year of continuous use of the MX the Portuguese paint manufacturer was completely satisfied. In a three-shift manufacturing process the progressive cavity pump from KNOLL could fully convince: After more than 6.000 hours in use no loss of flow or pressure occured.

But not only the abrasion- and corrosion-resistant construction of the pump contributed to this result but also its design principle with a stator in Even-Wall-technology – a standard in every MX-Pump from KNOLL. This stator is responsible for the fact that practically no back flow of media occurs, which is very welcome especially when abrasive media such as calcium carbonate have to be pumped. As a consequence no blast wear appears.

Another advantage of EvenWall-technology is its significant improvement of the stators characteristic, compared to a pump with conventional stator. This has quite a considerable effect on the cost-effectiveness. The picture shows the characteristic of a conventional stator (left line) and of a stator in EvenWall-technology (right line).

Overall the MX-Pump with its special design convinces not only because of the very high resistance to abrasive media but also on the level of operation efficiency and cost-effectiveness.

Our Diversity of Pump Materials: It’s Your Choice!

A good pump can be adapted to many different transport media and it’s the pump materials that make a decisive contribution to this. Therefor KNOLL Maschinenbau offers a wide range of materials for its progressive cavity pump, even usable in different combinations, so that for nearly any type of transport medium the right pump can be selected.

For its standard design KNOLL applies stainless steel in food quality for all components in contact with product. In addition, however, designs in cast iron are available for applications where stainless steel is not required. In both cases, ie stainless steel or cast iron, of course, all other advantages of the pump stay the same: Ease of servicegood cleaning ability, and of course the benefits of EvenWall-technology.

Why is stainless steel so often used in pumps? It is its high corrosion resistance which distinguishes it from other materials. Depending on the composition of the steel this corrosion resistance can be increased even further.  Hence KNOLL’s MX-Pumps can be fully made of stainless steel or using stainless steel only for all components in contact with product. Progressing cavity pumps fully made of stainless steel are more and more requested from manufacturers with very high hygiene requirements.

Elastomers also play an important role in progressive cavity pumps. For the MX-Pumps more than 100 different types of elastomers (among them many with numerous certificates) are available. This allows an individual adaptation and thereby chemical resistance for each pump to its transport medium. If in your case experience on the resistance of your medium is not available yet, swelling experiments in the KNOLL laboratory are possible at any time.

In particular, we keep in mind the consistent quality of each elastomer used: For every single application the exact same elastomer recipe is used so that the repeatability of the pump parameters remains the same. Especially when the progressive cavity pump is used as a metering pump this is very important: A replacement of the stator must not lead to a re-parameterization of the pump in the manufacturing process. Therefor KNOLL Maschinenbau guarantees for its MX-Pumps and its original spare parts high repeatability.

Finally KNOLL also provides a stator in Teflon for cases in which an elastomer cannot be used. Such solid stators are suitable for aggressive fluids, as often used in the chemical industry, for example in form of paints with solvents.

Pumping and Tempering Sensitive Media

Today many manufacturing processes are not possible without the use of pumps. And often not only the role of pure pumping, but also tempering is important, as the transport media must be kept on a very specific temperature level. The pump must therefore be able to temper – which means cooling or heating due to the specific process.

In the case of sensitive goods in transit it must be ensured that they do not get into contact with the tempering media. Any contamination must be ruled out. KNOLL Maschinenbau has therefore  specially designed its MX progressive cavity pumps, so that tempering with steam, water or oil is possible without contamination of the sensitive transport media.

In order to achieve this a double jacket on the suction housing as well as on the pump assembly gets applied. This solution offers several advantages:

  1. High pressure stability: The double jacket keeps up with a pressure of up to 5 bar, for example when the pump gets tempered in the context of an overall tempering of pipes and containers.
  2. Good tempering properties: The stator in EvenWall-design provides a relatively large surface area with even elastomer wall thickness and thus very good characteristics for tempering.
  3. Extremely easy to service: Even when fitted with the double jacket for tempering the MX from KNOLL remains an extremely easy to service pump because all parts are still equally accessible.
  4. Stator-Relining: If there is wear on the stator, it can be reprocessed. For this, the elastomer used is burned out, so that the stator shell can be used for a re-vulcanization. Cost savings and protection of the environment are the consequences.

Finally, it should be mentioned that this progressive cavity pump offers high efficiency and carries only very little heat on its transport medium. Therefore heating will practically not occur, so that a “well-tempered” pumping and transport operation is guaranteed with the MX from KNOLL Maschinenbau.

The Benefits of Progressive Cavity Pumps Compared to Other Pumping Systems

When a new manufacturing plant gets planned or an existing plant needs to be modernized, often the question of the right pumping system is taken into consideration: What type of pump is the correct one? The following list speaks in favor of the progressive (progressing) cavity pump:

  1. Gentle conveying of the medium: the pumping chambers in the pump assembly remain constant, so that the product gets neither crushed nor sheared. The non metal to metal contact of the progressive cavity principle is far superior when pumping abrasive particles in suspension.
  2. Different viscosities are equally well served: From low to high viscosity media the progressive cavity pump handles everything, even thixotropic or entrained air fluids. This makes it extremely flexible and versatile in its range of applications.
  3. No backflow into the pump: When stopped the progressive cavity pump closes like a slider (valveless pump) so that practically no backflow returns to the pump.
  4. Very good suction performance: With its excellent suction performance this pump is the right choice for emptying barrels, mixers and containers of all kinds (big bags). Progressing cavity pumps from KNOLL Maschinenbau offer a negative pressure of up to 0.2 bar absolute, when fitted as suction, submergible and following plate version.
  5. Metering accuracy: Due to low pulsation the progressive cavity pump offers very exact metering. An additional valve is not required.
  6. Linear characteristic curve: Since there is no backflow into the pump, the flow rate is increasing always proportional to the speed. Thus, the optimal efficiency of this pump extends over a very wide range.
  7. Suitable for high pressures: Progressing cavity pumps from KNOLL achieve a pressure increase of up to 80 bars, which makes them an interesting proposition for sophisticated engineering. The higher pressures are desirable for moving product greater distances and for applications involving extrusions.

The MX-Pumps from KNOLL therefore are used in a wide range of  different applications. Here is a selection of media that will be optimally promoted by this progressive cavity pump:

  • In the food and beverage industry: dairy products, raw and cooked vegetables, fruit mash, concentrates (eg juices), liquid egg dough, color and flavor, butter, cooked dishes, raw and auxiliary materials and finished materials for the confectionery industry, chocolate (with and without lumpiness), animal food;
  • In chemistry, biochemistry, pharmaceuticals and cosmetics: paints and coatings, resins, waxes, adhesives, raw and auxiliary materials for the pharmaceutical industry, peels, cosmetic products (including products for organic and natural cosmetics).

Pumps for the Pulp & Paper Industry

Paper doesn’t blush tells us the proverb. Its manufacturing process is thus not meant, as the production of many thousand sorts of paper is a very demanding process. Progressing Cavity Pumps from KNOLL can here be found in different places, for example directly on the paper machine (for coating color) or in the coating kitchen (for various chemical additives).

It’s the characteristics and product features of this pump that speak for its use in the pulp and paper industry:

Low Pulsation: Absolutely smooth transportation is given and even under fluctuating medium temperatures the characteristic curve remains constant. A precise metering of media of all kinds, which can also be highly viscous or abrasive, is guaranteed.

Large capacity: Capacities with flow rates of up to 200,000 liters per hour are possible with the (so far) largest model of the MX series, the MX100.

Minimum space requirements: With its stator built in EvenWall-technology MX-pumps need only little space and can therefor be used even even under difficult conditions.

Suitable for high pressures: Both, the rotor-stator unit, as well as the very robust cardan joint can easily work under high pressure. Progressive Cavity Pumps from KNOLL are generally delivered with a bearing block, so that axial and radial forces are not transmitted to the gearbox. As a result of this the gears are fail-save protected.

In practice you will find MX-pumps from KNOLL for example in the promotion of paper pulp, mostly in its hopper version. The latter allows to pump media such as pulp, which can be of little or no more free-flowing substance.

But you will also find the MX in the coating kitchen where different chemical additives need to be precisely metered and transported. In its special chemical design the MX-pump promotes calcium carbonate, fillers of all kinds, glues, latex, starch, coating color and titanium dioxide. In addition such media may be hot as for example coating color, or highly abrasive, environmentally harmful and dangerous. Performance and reliability of the pump are not affected by this.

Another advantage of the MX-pump is its spacious sealing chamber in which various sealing arrangements can be fitted, following many different needs and circumstances. Depending on the medium KNOLL can offer double acting mechanical seals for blocking pressure (in closed systems) or as a pressureless quench for cooling or lubrication of the sealing surfaces.

Overall progressing cavity pumps from KNOLL support the pulp and paper industry in its most cost sensitive factor: the use of materials (material consumption) to produce. Fast transportation even under high pressure, exact metering and very short holding time (for maintenance) contribute to achieve a cost-optimized production of paper.

Emptying Barrels containing Highly Viscous Media

High viscosity media are often stored in drums and must be retrieved from these for further processing. Since they can be so tough that there is no subsequent flow, special precautions have to be taken to make sure that their drum gets fully voided. Examples include ointments, pastes, greases, resins, silicones and adhesives. In the production of foodstuff highly viscous materials also appear: Peanut butter, tomato paste or dough are typical examples.

For these purposes KNOLL Maschinenbau offers its progressing cavity pump MX as submerged version for easy drainage of drums, mixers, agitators and big bags. The particular advantage of this type of pump is it that it can both transport tough to semisolid media and meter them while emptying the barrel except for very small rests. In addition to that transportation over relatively long distances with at the other end an exact placing in smaller containers is no problem. The MX-Pumps provide the pressure that is necessary in such situations, ranging from no pressure at up to 40 Bar.

The construction of the pump can follow very individual needs. A pneumatic control can be included (or omitted), as well as temperature regulation (heating for very high viscous media). In addition, the entire structure will be adapted to the size of the container to be emptied, so that both, normal 200-liter barrels, as well as smaller containers can be operated.

For the core of the system, the progressing cavity pump MX apply, of course, all the benefits of this series of pumps: Very good cleaning ability with intelligent separation points for easy disassembly and assembly as well as readiness for cleaning-in-place (CIP capability), gentle and low-pulsation conveyance of the cargo and the handling of high pressure due to the EvenWall technology, to name only a few.

In practical use the following plate is placed and fixed directly on the transport medium. Once the pumping starts, the following plate is moved down by using a pneumatic cylinder.

Seals between the plate and tap ensure that the cargo can escape only through the pump. The geometry of the following plate and the setting of the end points an almost complete emptying of the drum is reached. At the end of a discharge process, the follower plate is put back into its original position. It can then be easily cleaned or replaced.

Liquids, Metering Precision and Knoll’s MX Progressing Cavity Pumps

One of the main goals concerning the volumetric metering of aqueous to highly viscous liquids in containers (packages) is to achieve a high level of reproducibility. In Europe for example manufacturers of all industries have to comply with the (Council) Directive relating to the making-up by weight or by volume of certain prepackaged products.

Certain tolerances have to be respected, but of course not only for legal reasons: The metering accuracy is crucial to metering quantities and therefor for manufacturing costs. The smaller the tolerance, the smaller the fill quantity can be set.

The image (above) shows a “mono-pump” filling machine (named MFL) by Bünder & Schmitt, in which the MX-Pumps in CIP-capable version are employed. Such filling machines are used for example by Henkel or Bayer for filling of cleaning materials and pesticides.

The KNOLL MX progressing cavity pumps are highly competent in metering. In addition to the precise metering not only incompressible but also compressible fluids can get pumped without changing the structure of medium. A key feature is the standard set EVEN WALL (even elastomer wall thickness) which gives the MX-pump an absolutely precise and uniform sealing line. The precision of the sealing line helps to increase the quality of the reproducibility of the flow even under alternating pressure. Further it helps significantly to keep pulsation low.

So very shear sensitive media can be transported easily as they get prevented from damage by the EVEN WALL construction and the precise sealing line. In some cases heat input plays an important role. It is considerably lower in MX-pumps with their EVEN WALL stator compared to pumps with conventional cylindrical stators.

Another criterion which is important for metering, is the resistance of the materials not only for liquids to be pumped but also for the cleaning media and their temperatures. For this reason numerous materials are available from KNOLL, each corresponding to the fluids and carefully selected by our qualified laboratory.

Accessories used in the pump decide just as much on the level of metering accuracy as the metering pump itself. For each single request the necessary measurement and control technology gets individually designed and verified, so that a constant metering is demanded of a once calibrated pump or a simple on measured values dosage is, extensive accessories by KNOLL available.

Depending on the task, step motors, servo motors or induction motors can be used to support the MX-Pump in their exact metering.

The graph (above) shows the level of precision obtained in the measurement of a MX-Pump (for larger display click on the image). The idea was to code the amplitude and to measure its exact position with the help of a stepper motor and an encoder in order to be able to compensate it on the metering. Turned out that the metering was so extremly precise that it could get run without the encoder.
In practice MX-Pumps are already used in numerous cases where liquid amounts of a fraction of a drop have to be dosed under variances in viscosity, temperature and pressure.

MX-Pumps in the Paint and Coatings Industry

Manufacturing paints and coatings today is a high tech industry facing  high expectations from customers as well as from health-care and environmental regulations. Accordingly high are expectations in this industry on pumps which are used to transport and dose components and finished products.

The MX progressing cavity pump by KNOLL Maschinenbau has repeatedly shown proof of its power. For example with a paint manufacturer in Westphalia (Germany) who counts on the MX for carrying and filling emulsion paint because of its high efficiency: The MX easily builds up to 10 bar pressure at a very high degree of efficiency without any medium to be forced back into the pump.

The decisive factor here is the EvenWall-Design of the MX. Its stator is not a cylindrical one but turned (as visible on both fotos) so that together with the inside compressed elastomer it forms an “even wall”. The result of this principle is a significantly higher pressure resistance than with pumps formed of a (conventional) cylindrical stator.

Another important factor for chosing the MX for this paint manufacturer was the “hygiene” of the pump. For the processing of paints, the use of solvents is no longer allowed so that frequent and very specific cleanings of the pump are required. The MX convinces on this field with its low clearance volume design and its readiness for rapid disassembling (and reassenbling): clamping closures and screw unions in accordance with DIN allow to disassemble, to clean and reassemble the pump in minutes only. In the same way replace parts can be installed quickly and easily.

All in all the MX was so so convincing that meanwhile more than 50 units of this progressing cavity pump are in use today at this Westphalian manufacturer. So when it comes to pumping or dosing paints, varnishes and coatings the MX obviously is a good choice.