- Offer Profile
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The WITTE Pumps & Technology GmbH stands for efficient and extraordinary pump solutions and has been one of the leading pump manufacturers in the field of precision gear pumps since company founding in 1984. WITTE manufactures standard and special pumps for the chemical, pharmaceutical, food and plastics industry, as well as in the areas of offshore and marine engineering.
We always strive for new and more efficient developments to provide you with the best possible service. Therefore, we wish to inform you on our pages detailed about our products, developments, services, news and all other areas of our company.Visit us on:
Gear pumps
- WITTE is one of the leading manufacturers of gear pumps for the chemical, polymer processing, cosmetic & food industry. Our gear pumps are ideal to transport different media and are available both as standard solutions and custom designs. Housings, shaf, bearings and covers from our special pumps can be produced in different materials as desired. Thanks to the modular WITTE construction kit for friction bearings, gear pumps and axial shaft seals, our gear pump solutions offer our customers the greatest possible flexibility.
Advanced Technology! The new design for WITTE polymer gear pumps
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The next step in evolution of polymer pumps
The demands on plants, processes and equipment are constantly increasing. So to live up to the demand for greater efficiency, higher throughput and lower reject rates, Witte Pumps & Technology GmbH has completely overhauled its entire range of polymer pumps. In a bid to achieve more throughput, gentler handling and greater energy efficiency, the pumps in both the BOOSTER and PolyCore® ranges have been entirely reworked.
New: PolyCore® AT Discharge gear pumps
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High efficient discharge gear pumps
The PolyCore® AT design offers exceptional flexibility when it comes to installations beneath the polymer melting reactor. Customers can choose from three different flange geometries to ensure they are always benefiting from the best combination of reactors and pump flanges from both a technical and economical perspective.
The new gear geometries facilitate differential pressures of up to 320 bar for selected pump sizes. What’s more, the new design is rounded out with the usual variety of different material combinations. The most common of these combinations has to be a stainless-steel or carbon-steel housing with tool steel or aluminium-bronze friction bearings.
Advantages
- Lower bearing temperature, leading to lower stress on the polymer
- Optimised inlet geometry, leading to minimal pressure loss and therefore minimal dwell times of the polymer in the reactor
- Three different flange types each (EN 1092-1 or ANSI B16.5)
- Three different pressure versions (200 bar, 250 bar, 320 bar)
High efficient discharge gear pumps
The POLY-AT design offers exceptional flexibility when it comes to installations beneath the polymer melting reactor. Customers can choose from three different flange geometries to ensure they are always benefiting from the best combination of reactors and pump flanges from both a technical and economical perspective.
The new gear geometries facilitate differential pressures of up to 320 bar for selected pump sizes. What’s more, the new design is rounded out with the usual variety of different material combinations. The most common of these combinations has to be a stainless-steel or carbon-steel housing with tool steel or aluminium-bronze friction bearings.
Maximum flexibility
SX - Version:
- Flange geometry integrated in the housing
- Minimal installation space
MX - Version:
- Blind holes in flange
- Largest possible cross section
- Minimal pressure loss
- Ideally suited for highly viscous polymers
LX- Version:
- Flange with through holes
- Maximum flexibility for the installation
- Very low pressure loss
New: BoosterCore® AT Discharge gear pumps
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BoosterCore® AT - The next evolutionary step for high-pressure pumps in the polymer process
All sizes and flange geometries are available with connections that comply with EN 1092-1 and ANSI B16.5. It goes without saying that the company also offers housing variants for replacing existing pumps and debottlenecking, not to mention solutions for special requirements based on customer requests. By standardising on three gear widths for each centre distance, the distances between the respective pump sizes have been significantly reduced. This means it is now easier than ever to select the best possible – and therefore most cost-effective – pump size for each application.
Advantages
- Lower bearing temperature, leading to lower stress on the polymer
- Increased safety against shaft breakage due to overload
- Simplified spare part management thanks to the use of identical components for all series
- Higher efficiency, thereby
- Reduced heat input
- Energy saving = cost reduction
- Larger viscosity range
- Increased throughput of up to 40% without changing the
installation size
BoosterCore® AT - The next evolutionary step for high-pressure pumps in the polymer process
The series is the result of a complete rework of the used core components. The customer benefits from high flexibility of design and standardization. The BoosterCore® is available with flange geometries and connections that comply with EN 1092-1 and ANSI B16.5. It goes without saying that the company also offers housing variants for replacing existing pumps and debottlenecking, not to mention solutions for special requirements based on customer requests. By standardising on three gear widths for each centre distance, the distances between the respective pump sizes have been significantly reduced. This means it is now easier than ever to select the best possible – and therefore most cost-effective – pump size for each application.
The new gear geometries facilitate differential pressures of up to 320 bar for selected pump sizes. What’s more, the new design is rounded out with the usual variety of different material combinations. The most common of these combinations has to be a stainless-steel or carbon-steel housing with tool steel or aluminium-bronze friction bearings.
Maximum flexibility
SX - Version:
- Flange geometry integrated in the housing
- Minimal installation space
MX - Version:
- Blind holes in flange
- Largest possible cross section
- Minimal pressure loss
- Ideally suited for highly viscous polymers
LX- Version:
- Flange with through holes
- Maximum flexibility for the installation
- Very low pressure loss
Portfolio
Boosterpumps BoosterCore®
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Gear pumps for pressure increase
The reliable pressure increase pump for the polymer process.
BoosterCore® gear pumps from WITTE are used in the polymerization process to increase the pressure of medium to high viscous media. The hydraulically heated booster pump transports prepolymers and polymers, such as PET, PBT, PS, ABS and many others, in a very gentle manner. The heating is done through heat transfer oil or steam.
The core components such as shafts and friction bearings come from the WITTE unit block building system. The pressure increase pumps from the BoosterCore® series are used wherever particularly high pressure is needed for the process. High pressures are needed, among other things, for the granulation, fiber production or for spinning pumps. The design of the BoosterCore® pressure increase pumps can be adjusted to the needs of the plant and the customer’s requests.
Technical Features- Housing: Heat resistant carbon steel, e.g. 1.6582 · rust-free stainless steel 1.4313
with optional coating - Gears: Tool steel · nitrated steel · special steel · with optional surface coating · helical gearing · herringbone gearing (for extremely low-pulsation conveyance)
- Friction Bearings: Tool steel · NiAg (nickel-silver) · Al-bronze · special materials · with optional surface coating
- Shaft Seal: Viscoseal · stuffing box · (Vacuum viscoseal)
- Heating Systems: Heat transfer oil · steam
Operating Parameters- Viscosity: up to 40000 Pas
- Temperature: up to 350°C (660°F)
- Inlet pressure: Vacuum up to max. 120 bar (1740 psig)
- Differential Pressure:
Up to 250 bar (3225 psig)
- Pump Sizes: From 22/22 (4.7 cm3/U - 10 kg/h) up to 280/280 (12000 cm3/U - 30000 kg/h).
The values listed are maximum values and must not coincide under certain circumstances.
- Housing: Heat resistant carbon steel, e.g. 1.6582 · rust-free stainless steel 1.4313
Extrusion pumps ExtruCore®
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Efficient. Pulsation-free. Gentle.
Melt pumps for extrusion
The extrusion gear pump is mainly used in connection with extruders or kneaders. They lower the naturally existing pulsation and uneven transportation, particularly of single-screw extruders. The extrusion pump is also used as a melt pump. It takes over the establishment of the required transport pressure, which is needed for the downstream equipment.
Efficient pressure build-up
In the gear pump, the pressure build-up occur significantly more efficiently than in the extruder itself. The extruder is relieved through the use of an extrusion pump. Significantly less energy or heat is added to the polymer. The melt pump thereby contributes to the gentlest possible transportation. The ExtruCore® pump is indispensable for the production of precise foils or micro-granulate.
Robust and flexible
The robust design and wear-resistant materials make the ExtruCore® indispensable for extrusion. It can also be used to transport natural rubber and soft PVC through different special designs.
The WITTE fast-changing color design is perfect for master batch applications with frequently changing colors.
Technical Features- Housing: Heat resistant carbon steel, e.g. 1.6582 · rust-free stainless steel 1.4313 ·
with optional coating - Gears: Tool steel · nitrated steel · special steel · with optional surface coating · helical gearing · herringbone gearing (for extremely low-pulsation conveyance)
- Friction Bearings: Tool steel · NiAg (nickel-silver) · Al-bronze · special materials · with optional surface coating
- Shaft Seal: Viscoseal · stuffing box
- Heating Systems: Electrically, by means of heating cartridges · optional cover heating
Operating Parameters- Viscosity: up to 40000 Pas
- Temperature: up to 400°C (752°F)
- Inlet pressure: Up to max. 120 bar (1740 psig)
- Differential Pressure:
Up to 250 bar (3625 psig) ·
special models also available for higher pressure differentials - Pump Sizes:
From 22/22 (4.7 cm3/U - 10 kg/h) up to 280/280 (12000 cm3/U)
Intermediate sizes, with narrower gear wheels for higher differential pressure, are possible, e.g. 140/90 (690 cm3/U).
The values listed are maximum values and must not coincide under certain circumstances. - Housing: Heat resistant carbon steel, e.g. 1.6582 · rust-free stainless steel 1.4313 ·
Extrusion pumps [EXTRU] for quick color change
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Melt pump for quick color change
The WITTE Quick Color Change (QCC) is perfect for master batch applications with frequently changing colors. This extrusion melt pump is equipped with two regulating screws and a separate product flange. The regulating screws allow for a color or product change during running operation. The position of the screws influences the direction of the lubricant flow. This can either be guided back into the main flow or out of the pump through a separate product flange. This prevents contaminated material from the previous application from entering the new product flow.
Advantages:
- Saving of raw material through a quick color change
- Cleaning time is shortened when color or material is changed
- Overall throughput of the plant is increased through shorter cleaning time
- Also suitable for sensitive polymers, such as PC or PMMA
Chemical pumps ChemCore®
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Gear pumps for chemical applications
ChemCore® gear pump to transport and dose low to medium viscous media.
The application range reaches from classic transfer and dosing tasks in the chemical and pharmaceutical industries to the transportation of monomers, oligomers and prepolymers during polymer production. Through decades of construction experience and optimal material selections, these chemical pumps are suitable for even the most difficult of tasks and maintain their reliability and dosing accuracy in vacuum and high pressure applications. Typical areas of application for this pump type can be found in the chemicals, cosmetics, food industries, petrochemicals and polymer industries.
WITTE chemical pumps from the ChemCore® series can be operated horizontally, vertically and also as submersible pumps lowered in medium.
Different designs for different tasks- ChemCore®: Chemical gear pump standard version
- ChemCore® MINI: Mini chemical pump for finest metering and dosing tasks
- Pump for fiber processing
- Metering pump standard version
Technical Features- Housing: Non-alloyed and alloyed steels · tantalum · titanium · Hastelloy · ceramic
- Gears:
1.4112 but also all other processable ceramics and metals, e.g. 1.4571, Ferralium, ferro titanite Hastelloy, etc. ·
with optional surface coating · spur gearing - Friction Bearings: Carbon · NiAg (nickel-silver) · silicon carbide · zirconium oxide · tool steel · Al-bronze · special materials · with optional surface coating
- Shaft Seals: Single mechanical seal (ED) · Single mechanical seal with buffer fluid (AD) · Double mechanical seal with buffer fluid (DD) · magnetic coupling · stuffing box · viscoseal
- Heating Systems: Steam · water · heat transfer oil · electrical
Operating Parameters - Viscosity: 0.5 to 1000000 mPas (cP)
- Temperature:
Up to 300°C (580°F)
higher temperatures upon request - Inlet pressure:
Vacuum of max. 15 bar (215 psig)
higher with magnetic drive - Conveying Pressure / Differential Pressure: Up to 120 bar (1740 psig)
- Pump Sizes: From 22/6 (1.28 ccm/rev – 20 l/h) to 280/280 (12000 ccm/rev – 170000 l/h).
The values listed are maximum values and must not coincide under certain circumstances.
CHEM-LZ Replacement Pumps for Hermetic LZ Series
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100% Compatible with the original
We offer broad expertise in the field of gear pumps and are therefore the ideal partner when it comes to replacing your old Hermetic LZ gear pumps. Hermetic has discontinued this series, although a large number of pumps are still in active operation. However, this is no reason for you as a customer to worry. WITTE offers exact replicas for easy replacement. We supply you with the complete pump including coupling connection with identical dimensions. This is a double advantage for our customers, because the system does not have to be extensively rebuilt and the core components come from the established WITTE modular system.
The usual high availability of spare parts is thus also ensured for these pumps at all times. Furthermore, it is also possible to upgrade the pumps by using other materials from our portfolio. This may be necessary if requirements have changed over time or the performance of the pump is not optimal.
This saves money and time. We guarantee maximum service life and accuracy of fit for the ChemCore® LZ. On request, however, we can also equip your plant with the chemical pumps of the WITTE ChemCore® series. Just as you wish.
Technical Features
- Housing: 1.4571 - others on request
- Gears:1.4112 - others on request
- Friction Bearings: Carbon, SiC, ZrO2, NiAg, Alu-Bronze
- Shaft Seals: Single or double mechanical seal, optional stuffing box
Operating Parameters- Flow rate: 0.05 bis 120 m³/h
- Differential pressure: 25 / 40 bat
- Viscosity: 0.3 to 5.000.000 mPas
- Temperature: -20 to 200 °C
- Pressure levels: 25 / 40
The values listed are maximum values and must not coincide under certain circumstances.
Chemical pump ChemCore® Plus
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The new chemical pump for an extended range of applications
Conventional gear pumps have a limited range of applications due to their design. There are applications that cannot be realized at all or only with considerable modifications and costs. These include the low-pulsation delivery of low-viscosity fluids against high differential pressures in a wide temperature range. Until now, this was only possible to a limited extent with gear pumps. This is because the low viscosity combined with high differential pressures harbors a major risk: Although the medium flows quickly into the friction bearing, a sufficient lubricant film is not formed there, which quickly leads to contact between the journal and the bearing. The use of special materials can compensate for this to a certain extent.
A challenge to our taste
Our goal: customized gear pumps with maximum process reliability. Creating solutions that no one else offers is what excites us and drives us. With our focus on innovation, technology and quality, we have succeeded in expanding the range of applications for gear pumps and improving the technology in key areas.
The result
Thanks to its pioneering design and precisely matched material composition, our innovative ChemCore plus pump achieves uniform pressure even at low viscosities and consistently over a wide temperature range. It is particularly suitable for applications where pulsation-free pumping of fluids of the lowest viscosity against high pressure is required.
Technical Features
- Housing: Carbon and alloy steel - Tantalum - Titanium - Hastelloy® - Ceramics
- Gears:1.4112 but also all other processable ceramic and metal materials, e.g. 1.4571
- Friction Bearings: Carbon - NiAg (nickel-silver) - silicon carbide - zirconium oxide - tool steel - aluminum-bronze - special materials - optionally with coating
- Shaft Seals: Single internal, single external or double mechanical seal - Stuffing box - Magnetic coupling
- Heating: Steam - Water - Heat transfer oil - Electric
Operating Parameters
- Differential pressure: up to 100 bar(a)
- Viscosity: 1 up to 1.000 mPas
- Temperature: Up to 300 °C - higher temperatures on request
- Pump size: 0,2-9-5,5 up to25,6-36-36
The values listed are maximum values and must not coincide under certain circumstances.
Discharge pumps [POLY]
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Gear pumps for the discharge of highly viscous media from melt reactors.
Reliable and robust pumps are needed to empty reactors and containers particularly during the polymerization process. The pumps transport the melt throughout the process. The highly viscous material must be transported from a reactor under vacuum. Discharge pumps from the PolyCore® series from WITTE are specifically created for this task. The customer can choose between a standard design or an individual design according to their requirements.
Technical Features- Housing:
Non-alloyed and alloyed steels · cast steel
with optional surface coating - Gears:
Nitrated steel · tool steel · special steel
with optional surface coating · helical gearing · herringbone gearing - Friction Bearings: Tool steel · NiAg (nickel-silver) · Al-bronze · special materials · with optional surface coating
- Shaft Seals: (Vacuum) viscoseal · stuffing box · combination of viscoseal and stuffing box · double-action, buffered mechanical seal
- Heating Systems: Heat transfer oil · steam
- Viscosity: up to 40000 Pas
- Temperature: up to 350°C (662°F)
- Inlet pressure: Vacuum to max. 40 bar (580 psig)
- Differential Pressure: Up to 250 bar (3225 psig)
- Pump Sizes: From 22/22 (4.7 cm3/U - 10 kg/h) up to 280/280 (12,000 cm3/U - 30,000 kg/h). Intermediate sizes, with wider gear wheels for lower differential pressure, are available as standard, e.g. 152/254 (3,170 cm3/U).
The values listed are maximum values and must not coincide under certain circumstances.
- Housing:
Non-alloyed and alloyed steels · cast steel
Metering pumps [CHEM-SP]
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Metering pumps are used in different sectors. For example, in fiber production. Synthetic chemical fibers are gaining importance. They are required for many different applications such as textiles, linens, brushes, etc. WITTE dosing pumps ensure that the polymer melt in the process is transported evenly and reliably to the corresponding locations in the process. A constant flow rate is very important to ensure consistent quality.
Media with very low viscosities can be safely and precisely transported in other applications as well. High efficiency and a long life expectancy characterize this series of pumps.
Technical Features- Housing: Stainless steel · optional with coating
- Gears: Stainless steel · optional with coating
- Friction Bearings: Carbon, NiAg (nickel-silver), silicon carbide, zirconium oxide, tool steel, Al-bronze, optional: special materials, surface coating
- Axial shaft seals: Stuffing box
- Heating System: Heat · transfer oil · steam · optional heating cartridge
- Friction bearing (part of housing): Stainless steel · optional with coating
- Viscosity: Up to 100.000 mPas
- Temperature: Up to 350°C
- Suction Pressure: Up to 250 bar
- Differential Pressure: Up to 120 bar (1.740 psig)
- Pump sizes: 0,16 ccm/U up to 2,4 ccm/U
The values listed are maximum values and must not coincide under certain circumstances.
Mini dosing pumps [CHEM-M]
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Small metering pumps from 0,2 ccm/rev up to 2,95 ccm/rev.
Reliable dosing even in difficult applications
Through decades of construction experience and optimal material selections, this pump type is suitable for even the most difficult of tasks and maintains its reliability and dosing accuracy in vacuum and high pressure applications.
Typical areas of application for this pump type can be found in the chemicals, cosmetics and food industries as well as in petrochemicals.The ChemCore® MINI takes over the finest dosing tasks with the highest precision. The smallest available pump currently has a specific displacement volume of 0.2 cm3/rev. Smaller pumps are possible on request. Another highlight from this WITTE series is the availability of different materials for casings, gears and covers.
Technical Features- Housing: Stainless steels, tantalum, titanium, Hastelloy®
- Gears: 1.4112 (440B) but also all other processable ceramics and metals, e.g. 1.4571 (316Ti), Ferralium®, Ferro Titanite®, Hastelloy®, etc.,
optional: surface coating, - Friction Bearings: Carbon, NiAg (nickel-silver), silicon carbide, zirconium oxide, tool steel, Al-bronze, optional: special materials, surface coating
- Shaft Seals: Single mechanical seal (ED) • Single mechanical seal with buffer fluid (AD) • Double mechanical seal with buffer fluid (DD) • Magnetic coupling, stuffing box,
- Heating System: Steam, water, heat transfer oil, electrical
- Viscosity: 0,5 to 1.000.000 mPas
- Temperature: up to 300 °C (580 °F),
higher temperatures upon request - Suction Pressure: Vacuum to max. 15 bar (215 psig),
magnetic drive to max. 25 bar (363 psig) - Differential Pressure: Up to 120 bar (1.740 psig)
The values listed are maximum values and must not coincide under certain circumstances.
Gear pumps with magnetic coupling
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The magnetic coupling is equal to contact-free drive and seal. Magnetic
coupling pumps are used if critical media has to be transported. The seal
ensures that the pumps work 100% securely and without leaking. The magnetic
coupling is particularly ideal for hazardous substances that should not
escape into the enviroment.
The coupling is hermetically sealed and can be designed with different sensors for monitoring and in different variations and materials. A magnetic coupling is used in combination with a chemical pump by default.Operating parameters
- Suction side pressure: max. 700 bar(a)
- Viscosity: 1 up to 30.000 mPas
- Temperature: 450 °C
Food pumps
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Easy to clean and individually designed
Stainless steel gear pumps to transport and dose low to middle viscous media.
Through decades of construction experience and optimal material selections, this pump type is suitable for even the most difficult of tasks and maintains its reliability and dosing accuracy in vacuum and high pressure applications.Typical areas of application for this pump type can be found in the chemicals, cosmetics and food industries to transport, for example, margarine or vegetable oils. This pump type can be heated (hydraulically or electrically) as well as unheated. The modular WITTE construction kit for friction bearings, gears and axial shaft seals offer the highest degree of flexibility for users. The pump has different rinse connections for better cleaning. A design with little dead space was considered during the construction; a completely dead space free design is not possible due to the construction.
Technical Features- Housing: Stainless steel · Tantalum · Titanium · Hastelloy®
- Gears: Stainless steel · Ferralium · Ferro Titanite® · Hastelloy® · ceramic materials · optional even with coating
- Friction Bearings: NiAG (nickel-silver) · Silicon carbide · Zirconium oxide · Other materials on request
- Shaft Seals: Single and double mechanical seal · Radial shaft seal ring · Magnetic coupling · optional seals from third-party providers (with FDA approval)
- Heating System: Hydraulic · Electric
- Viscosity: Up to 500.000 mPas
- Temperature: Up to 200 °C
- Suction Pressure: Vacuum up to max. 15 bar
- Differential Pressure: Up to 135 bar
- Pump sizes: From 2,78-22-13 to 3200-180-180
WITTE Core Command - pump controller
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From now on, WITTE PUMPS & TECHNOLOGY also offers the suitable control for its pumps. Together with Blue Automation, a specialist for automation technology, the WITTE Core Command control was developed. This type of control is specially designed for use with WITTE gear pumps, but can also be used with pumps from other manufacturers.
The OEM solution
- WITTE offers a special service for OEM customers: gear
pumps specially designed for your requirements.
The transport task is analyzed together with the customer and an initial solution is created. A pump is designed and a prototype created dependent on the required amount. The customer tests this prototype extensively and the results are discussed together.
Should there be any requests for changes, these will be considered in the design. On request, the pumps can also be equipped with the customer’s label and can be delivered as quickly as possible through call-off contracts. 
Foam dosing
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A manufacturer of machines to create extinguishing foam requires a gear pump to
dose the foaming agent. The fluid is highly corrosive and tends to crystallize.
The problem is analyzed in a meeting with WITTE engineers and discussed with the
customer. Only special materials for the friction bearings, gears and seals
could ensure safe operation. Further process parameters were adjusted and
optimized throughout the project.
A customer-specific product was designed in the end while complying with all guidelines. All technical and commercial requirements were fulfilled.
Hose extrusion
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The manufacturing of plastic hoses for medical applications has the highest
demands regarding the quality of all required components. This includes the melt
pump. This special pump was not available on the market.
The manufacturer of the extrusion line contacted WITTE with the request to create such a pump. All customer requirements, such as easy cleaning and special materials, were included in this special pump. After an appropriate development period, WITTE was able to deliver a finished product to the OEM customer under compliance with all desired guidelines.
OEM hose test
- The goal for WITTE was to develop a pump for a mobile hose test stand. The OEM customer had the following requirements: 250 bar system pressure, very robust, compact design and the lowest weight. Since WITTE already had experience with high system pressures, the customer was able to receive a pump system within the shortest development time. After an extensive test phase, which also included use in the offshore sector, small changes were included in the series production. The OEM customer now has an optimal pump system customized to their needs.
Technology
- WITTE gear pumps are continually developed and are therefore always contain the most current technical innovations. We dedicate extra attention to the core components of our pumps. Bearings, shafts and seals can be combined in a variety of materials and designs.
Axial shaft seals
- Seal technology
Each rotating pump has a drive shaft that has to be sealed in some way. Sealing can be performed through a magnetic coupling, a stuffing box packing, a viscoseal with reverse conveyance threads, a single or double mechanical seal, a multiple lip seal or through combinations of the previously named systems.
Depending on the chemical pump type and place of use, different systems may be used. The limitation of the selected width of the seal types is defined by the process parameters. Pressure, temperature and viscosity are decisive factors that influence or limit the selection of the seal. 
Magnetic couplings
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The magnetic coupling is a special form of sealing that is possible without
rotating seal surfaces. That is why these are also described as “seal-less
pumps”. With the magnetic coupling, the product space and atmosphere are
hermetically separated from each other through static seals; the torque is not
transferred through a classic shaft connection, but rather only through magnetic
field coupling from the drive to the pump. The magnetic coupling works without
slip (synchronous magnetic coupling). This means that the pump speed always
corresponds to the drive speed as long as the maximum transferable torque is not
exceeded.
This form of sealing is always recommended if an escaping of medium must be avoided under all circumstances, for example, with toxic media. Since this seal variation is maintenance-free, it is often an attractive alternative to double seals. Furthermore, they are suitable for high system pressures (up to 700 bar), because both front sides of the shaft are exposed to the suction pressure and therefore no axial powers act upon the shaft.
Mechanical seals
- A variety of seal variations are available for WITTE ChemCore® chemical pumps. In addition to mechanical seals - depending on the process - magnetic couplings or radial shaft seals are also installed. In individual cases, chemical pumps from the ChemCore® series can also be sealed threaded shaft seals. The use of seals is determined by the suction pressure, viscosity and temperatures.
Threaded shaft seal
- The threaded shaft seal is the standard seal for WITTE ExtruCore® and BoosterCore® pumps, however, it can also be used as a special variation for PolyCore® pumps. It is also described as a viscoseal and can optionally have a heated or cooled design. This dynamic seal can also be used for high temperatures. The application area of seals is generally determined by the suction pressure and the viscosity of the pumped medium. The viscosity of the medium, however, may also be influenced by tempering.
Radial shaft seals
- Radial shaft seals cover the drive shaft to the atmosphere outside of the pump. They are located permanently in the casing or casing cover. The sealing lip is on the surface of the rotating shaft and is normally pressed from a spring and the pressure radial on the shaft surface. To prevent wear on the rubber lip and to ensure the seal effect, the shaft must have a high surface quality and hardness.
Seals from other manufacturers
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WITTE offers its own comprehensive seal program for gear pumps that can be used
for the majority of cases.
On request and for special application cases, however, seals from other manufacturers can be installed as well. We work together with renowned companies such as Eagle Burgmann, Flowserve, DEPAC, AESSEAL, Chesterton or HECKER.
Even the combination of WITTE seals with external seals is possible on request from the customer.
Stuffing box
- The stuffing box is a comparably simple and extremely robust shaft seal for WITTE gear pumps. This can be designed, if necessary, as a double seal with buffering medium. A braided packing made of expanded pure graphite with textile fiber is normally used; other materials are available depending on the application.
Buffer fluid systems
- For certain batch processes (for example, with the
production of polyester), the shaft seal must be made with difficult
conditions. On the one hand, the temperature, speed of the pump and
viscosity change during a batch; on the other hand, the pump shaft is sealed
off against high vacuum on the suction side. Under these conditions, only
double-acting, locked seal systems can be used; either a double stuffing box
or a double mechanical seal in “back to back” or “face to face” arrangement.
Both systems have to be supplied with a buffering fluid. This must be compatible with the transport product (in our example polyester) and temperature-resistant, because normally there are temperatures between 280°C and 300°C in the polyester production process.
The two illustrated supply systems are different
I) through a dynamic buffer fluid system and
II) through a static buffer fluid system.
Both systems contain a magnet-driven gear pump that ensures a forced circulation of the buffering medium. The operating temperature may amount to up to 350°C. Friction bearing technology
- Bearings are one of the core components for gear
pumps. The material and design must be carefully selected and coordinated
with each other to ensure safe and efficient operation of the pump.
Normally friction bearings are used in gear pumps. With this bearing type, the internal diameter is somewhat larger than the journals stored inside it. The transported medium penetrates into this small area through lubrication grooves through which a hydro-dynamic lubrication film is established from the medium in the bearing. The shaft “floats” in the bearing. For friction bearings lubricated with media, it must be ensured that the lubricating film does not tear. Otherwise the shaft can no longer be lubricated and it results in damage to shafts and bearings. This damage is normally irreparable and results in bearings and shafts having to be replaced. 
Friction bearing
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WITTE has a wide portfolio of different bearing designs and materials.
Many materials can be made even more resistant through additional coating. Friction bearings are used in gear pumps. Depending on the needs and applications, it may make sense to use other technologies.
Collar bearings
- Collar bearings are used with higher pressures on the suction side with shafts coming out on both sides. During start-up, the pressure may have an effect on the friction bearing through the casing balancing hole from the back to prevent a possible braking effect on the gears. The bearing is supported in the casing recess through the collar and cannot be pressed on to the gears. Collar bearings are also used if they are larger pumps.
Threaded shaft seal
- The threaded shaft seal is the standard seal for WITTE ExtruCore® and BoosterCore® pumps, however, it can also be used as a special variation for PolyCore® pumps. It is also described as a viscoseal and can optionally have a heated or cooled design. This dynamic seal can also be used for high temperatures. The application area of seals is generally determined by the suction pressure and the viscosity of the pumped medium. The viscosity of the medium, however, may also be influenced by tempering.
Gearing types
- Standard gearing
For WITTE gear pumps, there are three standard gearing types as well as a few special gearing types with smaller or wider gear pumps or adjusted geometries. Straight, helical and herringbone gearings are available to choose from for the pumps. Each of these gearing types have different properties that are important for the use of the gearing type. 
Spur Gear Design
- The spur gearing is the standard gearing for WITTE high pressure pumps as well as for the ChemCore® series. The spur gearing is distinguished through the non-existent axial thrust and has the best volumetric efficiency.
Helical gearing
- The helical gearing is mainly used as a standard gearing in polymer applications where a volume flow with the lowest possible pulsation is required. The helical gearing ensures a simultaneously high product quality through its properties. This gearing can be used for applications with differential pressures up to 250 bar.
Herringbone Gear Design
-
The herringbone gearing reduces the pulsation of the pumped medium compared to
helical and spur gearing. This is an advantage particularly for the quality of
the end product.
- Less pulsation
- Lower stress of polymer / shearing
- Lower heating of product (dependent on process)
- Alteration of existing pumps possible