Pumps for the pulp and paper industry: how to choose them

Pumps for the pulp and paper industry are centrifugal process pumps that continuously handle water, cellulose pulp, chemicals and additives, which are often abrasive or aggressive. The choice depends on how much fibre and solids the fluid contains, how aggressive it is and which sealing system is required. Since 1950 CDR Pompe has designed and manufactured mechanical seal and magnetic drive centrifugal pumps, in steel, in plastic and lined, which are also used in paper mills.

Why does the paper industry need specialised pumps?

A paper mill pump is a pump selected to run continuously with fluids that change along the process, from fibre stock to process water and chemicals. There are four main challenges:

• fibres and suspended solids, which can clog an unsuitable impeller and wear the internal parts;
• abrasion and corrosion, which cause costly downtime and frequent maintenance in paper mills;
• large volumes in continuous service: flow rate, head and energy efficiency weigh on operating costs, because energy is one of the main cost items in a paper mill;
• different stages in the same plant: from pulp preparation to refining and water treatment, each stage requires a different configuration.

This is why the pump must be selected on the actual fluid of each stage, not only on flow rate and head. CDR Pompe's applications in the sector are on the dedicated page on pumps for paper mills.

Which fluids are handled in papermaking processes?

A paper mill handles four families of fluids:

• wood pulp and cellulose pulp, from slushing in the pulper to refining: a stock with suspended fibres that, as consistency increases, behaves like a viscous fluid;
• process water and white water, i.e. the water that separates from the stock on the paper machine and is recirculated, containing fines and mineral fillers;
• auxiliary chemicals, such as sizing agents, dyes, bleaching agents and additives, which are often corrosive or hazardous;
• fibrous sludge and effluents, sent to water treatment.

What does a wood pulp pump need?

A wood pulp pump must let fibres through without clogging and must withstand wear. It needs:

• open impeller, with no front shroud, which lets fibres and particles through without build-up;
• wide passages inside the pump;
• a seal suited to the duty: single or double mechanical seal for dirty liquids and liquids with particulate; magnetic drive, in the version for solids, when tightness is also required;
• materials compatible with the fluid, in terms of both abrasion and chemical attack;
• viscosity within the pump's range: CDR data sheets give 0.5–180 cSt for its centrifugal pumps (0.5–150 cSt for UTN, ETN EVO and DTN). With very dense fluids, a positive displacement pump should be considered.

Before selection, the concentration, particle size and hardness of the solids and the presence of fibres must be declared. For high concentrations of fibres and solids, pump sizing is defined with the CDR Technical Office.

Centrifugal pumps for the paper industry: advantages and applications

A centrifugal pump is a pump in which a rotating impeller transfers energy to the fluid and drives it towards the volute, generating flow rate and head with a continuous flow. In a paper mill it offers high flow rates (up to 300 m³/h for CCN and UTS EVO and 250 m³/h for UCL and CCL, at 2,900 rpm), simplified maintenance thanks to the pull-out design shown in CDR data sheets, and adaptability to the different stages by changing impeller, seal and materials.

Typical applications are the circulation of white water and process water, the transfer of stock within the pump's viscosity range, the transfer and dosing of chemicals and the handling of effluents sent to water treatment. For effluents, see also Pumps for industrial wastewater [conditional link: the EN page does not exist yet (404 on 23/10/2026). Activate only after the IT article 7d2c and its EN version are published; otherwise remove the link and keep the plain text].

How do you choose the right impeller for fibrous fluids?

The impeller is chosen according to the fibre and solids content and the required head:

• closed impeller: blades enclosed between two shrouds, higher efficiency and head; suitable for clean fluids, such as many dosing chemicals;
• open impeller: no front shroud, with the blades exposed and close to the casing; it lets fibres and particles through without clogging, with slightly lower efficiency and lower head;
• vortex (recessed) impeller: set back from the volute, it moves the fluid by creating a vortex, so most of the liquid does not touch the blades. It is widely used on the market for very fibrous or stringy fluids, with lower efficiency;
• channel impeller (single or double channel): a closed impeller with a few wide channels, generally used for liquids laden with solids and long fibres.

CDR Pompe produces pumps with closed and open impellers: the open impeller is used on the magnetic drive X Series (XTS-B and XTN-BL) and, as an open radial impeller, on the lined and plastic mechanical seal range: UCL and CCL are available with a closed or open impeller. CDR data sheets do not list vortex or channel impellers: for fluids with a high solids concentration, the configuration is defined with the CDR Technical Office. Find out more: centrifugal pump impeller · pumps for fluids with solids [conditional link: the EN page does not exist yet (404 on 23/10/2026). Activate only after the IT article 6a6a and its EN version are published; otherwise remove the link and keep the plain text].

Magnetic drive pumps in the paper industry: when are they needed?

A magnetic drive pump is a centrifugal pump with no mechanical seal on the shaft: the motor turns an outer magnet assembly which, through a containment shell, drives the inner magnet assembly connected to the impeller. The hydraulic circuit remains isolated from the atmosphere.

In a paper mill it is the recommended choice for toxic, corrosive or costly auxiliary chemicals, when a leak would put operators, the plant and the environment at risk. Without a dynamic seal, wear-related leaks, auxiliary flushing and periodic replacements are also reduced. There are two limits to be aware of:

• a standard magnetic drive pump is designed for clean liquids. For fluids with solids, CDR Pompe has developed the X Series, with an open impeller and wide flushing channels that keep the bushings and the containment shell cool; if the solids exceed the limits of the X Series, CDR considers a mechanical seal centrifugal pump or a pre-filter;
• it must not run dry, because the fluid lubricates and cools the bushings and the shaft: it is protected with a level probe, a flow switch or temperature monitoring.

In potentially explosive atmospheres, CDR Pompe offers ATEX 2014/34/EU compliance for Zone 1 and Zone 2 on request on its main magnetic drive series (UTS, XTS, ETS) and on its centrifugal pumps. Find out more: Magnetic drive pump · mechanical seal pump · ATEX pumps.

Which materials resist abrasion and corrosion?

The material of a pump is chosen on three variables: chemical compatibility with the fluid, operating temperature and duty cycle. In a paper mill, abrasion also matters: an incompatible material is subject to corrosion, degradation or accelerated abrasion.

Material	CDR guidance	Watch out for
AISI 316 stainless steel (1.4408)	Mechanical strength, high pressures and temperatures; wetted parts of UTS EVO, ETS and XTS-B	Highly acidic fluids or fluids with a high chloride content: a specific assessment is needed
Polypropylene	Low-concentration acids, detergents, fluids without abrasive components, moderate temperatures	Abrasive fluids and very aggressive solvents
PVDF	Excellent chemical resistance, including to UV rays; water treatment and chemical processes	Narrower temperature range than PFA
PFA	Maximum chemical resistance, highly reactive fluids	Higher investment
ETFE	Structural strength, fluids with abrasive components and high mechanical stress	Medium-to-high cost

Source: centrifugal pump materials and CDR data sheets.

Lined pumps combine a sturdy metal body with an internal lining in PP, PVDF, ETFE or PFA, which forms a continuous barrier between the corrosive liquid and the metal parts. See steel or lined pumps · material compatibility of CDR pumps.

When should you choose stainless steel pumps?

Stainless steel is the choice when mechanical strength, higher pressures and temperatures are needed, or when the fluid requires steel for compatibility reasons. For example, in thermal oil temperature control circuits, the UTS EVO runs in continuous service with fluids up to +300 °C. With highly acidic or chloride-rich fluids, steel must be assessed case by case; if it is not compatible, CDR Pompe offers lined pumps.

Which CDR pumps can be considered for papermaking processes?

The table summarises the CDR series most relevant to paper mill fluids, with data from the technical data sheets. The use shown is the one stated in the data sheet of each series: the final selection is made on the actual fluid data, with the CDR Technical Office.

Series	Technology and impeller	Wetted parts	Fluid temperature	Max flow rate / head (2,900 rpm)	Use stated in the CDR data sheet
XTS-B	Magnetic drive · open	Stainless steel 1.4408, diamond-coated SSiC bushings	–40 / +180 °C	70 m³/h · 65 m	Corrosive, toxic or hazardous liquids with a high solids concentration; ATEX Zone 1 inside and outside
XTN-BL	Magnetic drive · open	PFA lined, diamond-coated SSiC bushings	PFA –50 / +160 °C	70 m³/h · 60 m	As XTS-B, when a PFA lining is required
CCN	Mechanical seal · closed	PP, PVDF, PEHD	PP 0 / +70 °C · PVDF –15 / +90 °C	300 m³/h · 100 m	Corrosive liquids, liquids laden with solid particles, mother liquors, chemical wastewater
CCL	Single or double mechanical seal · closed or open	PP lined	–10 / +70 °C	250 m³/h · 75 m	Duties with PP-compatible fluids
UCL	Mechanical seal · closed or open	PFA, PVDF, PP lined	PFA –50 / +140 °C · PVDF –30 / +100 °C · PP –10 / +70 °C	250 m³/h · 75 m	Corrosive, aggressive and hazardous liquids, slightly contaminated or clean, with low viscosity
UTS EVO	Magnetic drive · closed	Stainless steel 1.4408	–140 / +300 °C (UTS-B EVO –100 / +250 °C)	300 m³/h · 100 m	Continuous 24/7 service; can also be customised for energy saving
ETS	Magnetic drive · closed	Stainless steel 1.4408	–40 / +180 °C	45 m³/h · 42 m	Less demanding duties; toxic, hazardous and flammable liquids, mainly clean
UTN	Magnetic drive · closed	PFA, PVDF, PP lined	PFA –50 / +160 °C · PVDF –30 / +100 °C · PP –10 / +70 °C	150 m³/h · 60 m	Toxic, hazardous and aggressive liquids, mainly clean; also 24/7
ETN EVO	Magnetic drive · closed	ETFE or PP lined	ETFE –15 / +120 °C · PP –10 / +65 °C	60 m³/h · 35 m	Aggressive and hazardous liquids, slightly contaminated or clean, with low viscosity; intermittent pumping

Source: CDR technical data sheets (links in the table), read on 20/10/2026. Maximum pressure at 20 °C: PN 16 (ETS and ETN EVO PN 10). PN 16 and ANSI 150 flanges; special versions on request. Viscosity: 0.5–180 cSt (UTN and ETN EVO 0.5–150 cSt).

Customised solutions for complex paper mill plants

A custom pump is a pump designed to the specifications of a single plant, when the catalogue is not enough. For the most critical parts of a plant, the CDR Pompe Technical Office and R&D department design bespoke solutions: materials (AISI 304 and 316 steels, PP, PVDF, ETFE and PFA linings), options such as the zirconium oxide containment shell (on request on UTS and XTS) and diamond-coated SSiC or graphite bushings, in-line pumps such as the UTS-B IN LINE and vertical versions for collection and recovery tanks with corrosive fluids: the CVN in PP or PVDF and the magnetic drive TMVN in PVDF.

For integration into existing plants, CDR pumps are designed to ISO 2858 / EN 22858 and, for magnetic drive, to ISO 15783; the ETN EVO, for example, complies with the Sub-ISO 2858 standard, which makes it easier to install or replace without significant structural changes. Specifications are defined with the Technical Office at the kick-off meeting after the order. To reduce downtime, the Emergency Stock service supplies bare shaft pumps, close-coupled pumps complete with motor and strategic spare parts within 3-5 business days . Find out more: custom pumps · Services and Support.

How can you optimise pump efficiency in papermaking processes?

Optimising efficiency means running the pump close to its best efficiency point (BEP), where the flow is steady, the radial forces on the impeller are balanced and vibration is minimal. According to CDR, the purchase price normally accounts for less than 10% of the pump's total cost of ownership (TCO), while energy, operation and maintenance account for over 60%. The main levers:

• correct selection: an oversized pump increases energy costs and shortens service life. See the correct sizing of a centrifugal pump;
• impeller matched to the actual duty point: impeller trimming reduces head, flow rate and consumption when the pump runs above requirements;
• energy-saving configurations: the UTS EVO can be customised for energy saving, and on UTS and XTS the zirconium oxide containment shell is available on request, reducing absorbed power by up to 25%;
• scheduled and predictive maintenance: CDR offers scheduled maintenance and predictive analysis with customised programmes; predictive maintenance detects micro-vibrations, pressure variations and temperature anomalies before they turn into failures.

The full calculation is in the article How to optimize the TCO of a centrifugal pump.

How do you ensure long-term reliability and maintenance?

Reliability depends on three factors: the right configuration for fibres and solids, operation within the curve and data-driven maintenance.

• Wear and cavitation: wear is gradual and caused by contact with the fluid and particles; cavitation is the implosion of vapour bubbles, which quickly damages the impeller, and is prevented by checking theNPSH on the suction side.
• Critical spare parts in stock: impellers, bearings, seals, gaskets and flanges. See Spare parts warehouse and typical centrifugal pump failures.
• Correct start-up: theon-site start-up assistance checks alignment and operating parameters, especially on pumps with an external bearing bracket.

Why choose CDR Pompe for the paper industry?

CDR Pompe S.r.l. has designed and manufactured centrifugal pumps in Bollate (Milan) since 1950, with an ISO 9001 quality system, and operates in more than 50 countries through a network of distributors and partners. For the paper industry it offers:

• mechanical seal and magnetic drive pumps with closed or open impellers, in steel, in plastic and lined, including the X Series for liquids with solids;
• ATEX 2014/34/EU compliance for Zone 1 and 2 on request on its main magnetic drive series (UTS, XTS, ETS) and on its centrifugal pumps;
• pre-sales analysis with its own engineers and the design of custom pumps;
• water testing of every pump with a test report, and Attended tests on request;
• Emergency Stock within 3-5 business days, repairs in its in-house workshop and on-site support at start-up.

Send us the fluid, fibre and solids content, temperature, flow rate and head of your application: the CDR Pompe technical team will recommend the most suitable impeller, seal and materials. → Request a technical consultation · Paper mill · Services and Support

CDR Pompe S.r.l. — since 1950 · ISO 9001 — Via Raffaello Sanzio 57, 20021 Bollate (MI), Italy — +39 02 9901941 — info@cdrpompe.com

Frequently Asked Questions

Which pumps are best suited for moving wood pulp and cellulose pulp in a paper mill?

For wood pulp and pulp pasta, centrifuges with impeller open impellers without front counter-disks are required, and the passage channels are wide enough to allow the fibers to pass without clogging. For dirty liquids, one single mechanical seal or two pumps are used. The CDR charts indicate viscosities up to 180 cSt: with thicker doughs, a volumetric pump is considered.

How can the clogging of a centrifugal pump with fibrous and solid fluids in cartoning processes be prevented?

Clogging is prevented by starting from the actual data of the fluid: concentration, particle size and hardness of the solids and the presence of fibers. With these data, an impeller open pump and a pump with wide channels are chosen. A magnetic drive standard pump, designed for clean liquids, with many solids clogs and malfunctions; beyond the limits, pre-filtration mechanical seal is evaluated.

What is the difference between impeller closed, open, vortex and channel flow for fluids with fibers?

The impeller closed impeller has blades between two discs, offers more performance total head and is suitable for clean fluids. The open impeller allows fibers and particles to pass through with slightly lower performance. The vortex impeller, positioned backward from the intended position, is used for very fibrous fluids with lower performance. The impeller channel impeller has few wide channels for long fibers. CDR produces closed and open impellers.

magnetic drive Can a pump be used in a paper mill with fluids that contain solids?

Yes, but only with a dedicated version: the magnetic drive pumps standard versions are designed for clean liquids. For fluids containing solids CDR Pompe, it has developed the X Series, with impeller open and wide flow channels, in the XTS-B versions made of stainless steel and the XTN-BL version coated in PFA. It must never operate dry, because the fluid lubricates the piston rings.

Which materials should be chosen for a pump that moves abrasive and corrosive fluids in the paper industry?

The material is chosen based on chemical compatibility, temperature, cycle life and abrasion resistance. ETFE is suitable for fluids with abrasive components, PFA for maximum chemical resistance, PVDF for water treatment chemical processes. PP is not suitable for abrasives. AISI 316 stainless steel requires a specific evaluation with very acidic or chloride-rich fluids.

How can the operating costs and TCO of centrifugal pumps in a paper mill be reduced?

They are reduced by operating the pump close to the point of best efficiency (BEP), because the purchase cost accounts for less than 10% of the TCO, while energy, operation and maintenance exceed 60%. Proper sizing, cutting impeller, energy-saving configurations such as the zirconia oxide glass (up to –25% power) and predictive maintenance are important.