Vertical Sealless Pump Engineered for Specialty Chemical Processing

Vertical Sealless Pump for Specialty Chemicals

The vertical sealless pump has become the definitive solution for handling aggressive specialty chemicals in industrial environments. Unlike traditional horizontal pumps that rely on mechanical seals and submerged bearings, the vertical sealless design eliminates all dynamic sealing elements in the fluid path. The result is a leak‑free, zero‑maintenance pumping system that can run dry without damage, endure high solids loads, and resist even the most corrosive media. Engineers in chemical processing, pharmaceutical synthesis, and metal treatment trust these pumps for their ability to safely transfer acids, alkalis, solvents, monomers, catalysts, and slurries without risking fugitive emissions or unscheduled downtime.

At the heart of every reliable vertical sealless pump is a cantilever shaft design. The impeller is mounted on an extended shaft that is supported by out‑of‑liquid bearings located well above the fluid surface. This configuration removes the need for a bottom bushing or bearing in the sump or tank, eliminating the wear point that typically fails first in immersion pumps. The design also permits unlimited dry‑running, making the pump ideal for sump emptying, tank evacuation, and processes with wildly fluctuating liquid levels. Combined with advanced thermoplastic materials and engineered hydraulics, these pumps offer a service life many times longer than older mechanical‑seal architectures.

• Cantilever Seal‑Less Architecture: The motor shaft extends directly into the pump column without any intermediate coupling. An external anti‑friction bearing assembly supports both radial and axial loads above the liquid, ensuring that zero rotating parts contact the process fluid except the impeller itself. This eliminates mechanical seals, lip seals, and submerged bearings, delivering a lifetime of trouble‑free operation.
• Dry‑Run Capability Without Limits: Traditional pumps fail within minutes when starved of liquid because the mechanical seal overheats and the submerged bearing galls. The cantilever design has no such components, so it can operate indefinitely in a dry sump, aerated fluid, or during intermittent batch transfers without any risk of damage.
• Corrosion‑Resistant Thermoplastic Construction: Wetted components are manufactured from high‑grade polypropylene (PP), glass‑reinforced polypropylene (GFR‑PP), polyvinylidene fluoride (PVDF), or ultra‑high molecular weight polyethylene (UHMW‑PE). These materials are inert to most mineral acids, organic solvents, caustics, and halogens encountered in specialty chemical processes, eliminating cathodic corrosion and galvanic cells.
• Exceptional Solids‑Handling Capability: Optional vortex or semi‑open impellers permit the passage of suspended solids, fibres, and soft slurries up to several millimetres in diameter. The pump can move catalyst residues, precipitated crystals, and polymer particles without clogging, making it suitable for slurry recirculation and tank emptying in crystallisation and filtration applications.
• Customisable Immersion Depths: Standard columns are available in 600 mm, 800 mm, and 1000 mm immersion lengths, with the possibility to extend up to 3400 mm using an optional suction pipe extension. This flexibility allows the pump to be fitted into shallow sumps, deep chemical storage pits, and tall reactors with equal ease.
• Lowest Life‑Cycle Cost: With no mechanical seals to leak, no submerged bearings to replace, and no alignment requirements, the vertical sealless pump drastically reduces maintenance labour, spare part inventories, and production downtime. Over a plant’s operating horizon, the total cost of ownership is typically less than half that of a traditional sealed pump.

Why the Specialty Chemical Industry Demands a Vertical Sealless Pump

Specialty chemical processes involve aggressive reactants and intermediates that attack metals, degrade elastomers, and crystallise on cool surfaces. A conventional horizontal pump with a mechanical seal creates a leakage path that is both an environmental hazard and a reliability nightmare. Fugitive emissions of toxic or flammable vapours, seal face wear from abrasive slurries, and occasional catastrophic seal failure are daily risks. The vertical sealless pump completely removes the seal chamber, substituting it with a dry column that isolates the motor and bearings from the chemical environment. This architectural shift is not merely a performance upgrade; it is a fundamental safety and sustainability enhancement for any plant handling high‑purity, corrosive, or hazardous fluids.

In addition, specialty chemical reactors often operate under deep vacuum or elevated pressure, and the pump must be able to evacuate the heel from a vessel without losing prime. The vertical configuration enables the impeller to be placed right at the tank bottom, minimising net positive suction head required (NPSHr) and allowing total drainage. Combined with its dry‑running tolerance, the pump can repeatedly strip reactors and storage tanks without requiring operator intervention. For pharmaceutical intermediates, fine chemicals, and agrochemical blends, this level of fluid recovery not only saves valuable product but also simplifies cleanup and minimises cross‑contamination risk.

• Zero Leak‑ Path Design: By eliminating the mechanical seal, gland packing, and submerged bearing housing, the pump removes every possible escape route for hazardous liquids or vapours. The column‑to‑volute interface is a static gasket sealed with chemically resistant O‑rings, achieving emissions levels that satisfy the tightest environmental regulations.
• Resistance to Aggressive Chemical Blends: Specialty chemicals often contain mixed acids, organic solvents, oxidising agents, and halides. The pump’s thermoplastic wetted parts are selected from specific resin grades that resist swelling, stress cracking, and permeation, ensuring the mechanical integrity of the pump is maintained even after thousands of hours of exposure.
• Handles Wide Temperature Fluctuations: Depending on the material of construction, these pumps can tolerate continuous service from sub‑ambient temperatures up to 90 °C for PP, 120 °C for PVDF, and even higher for special grades. This allows them to manage both cold crystallisation liquors and hot cleaning‑in‑place (CIP) cycles without thermal stress cracking.
• Low NPSHr for Vac uum Operation Because the pump's impeller is deeply submerged and the column is primed by gravity, the net positive suction head required (NPSHr) is exceptionally low, often below 1 metre. This allows the pump to transfer boiling liquids, evacuate vessels under vacuum, and operate in high‑altitude installations without cavitation damage.
• Simplified Installation and Piping: The pump mounts directly onto a tank nozzle or a simple fabricated sump cover plate, requiring no foundation, grouting, or laser alignment. Process piping stays above the liquid level, so there is no need for flood suction lines or suction lift piping, significantly reducing installation costs and material offtake.
• Intrinsically Safe Design for Flammable Solvents: With no rotating metal‑on‑metal components submerged, the risk of frictional sparking is eliminated. When equipped with a flame‑proof motor and a conductive thermoplastic column, the pump can safely handle Category 1 and 2 flammable liquids in Zone 1 and Zone 2 classified areas.
• Reduced Product Contamination Risk: Mechanical seals often generate micro‑wear particles of carbon and ceramic that contaminate high‑purity specialty chemicals. The sealless design prevents any foreign particle ingress into the fluid stream, preserving the quality required for pharmaceutical intermediates, electronic‑grade chemicals, and catalyst solutions.

Specialty Chemical Applications

The vertical sealless pump excels across a diverse range of unit operations within specialty chemical plants. Its ability to safely transfer corrosive, toxic, and high‑purity fluids makes it the default choice for reactor off‑loading, circulation loops, scrubber systems, and solvent recovery. In pharmaceutical manufacturing, for instance, where active pharmaceutical ingredients (APIs) are produced in batches inside glass‑lined or stainless‑steel reactors, the pump must handle hot acidic quench solutions, organic solvent washes, and crystallisation slurries without introducing impurities or mechanical failures. The sealless cantilever design meets these requirements while also being compatible with the stringent cleaning validation protocols demanded by GMP environments.

Beyond pharmaceuticals, the polymer and additive sectors rely heavily on this pump for transferring monomers, plasticisers, and heat‑transfer fluids. The deep‑immersion capability enables continuous circulation of reaction mixtures around shell‑and‑tube heat exchangers, maintaining precise temperature control during exothermic polymerisations. Similarly, in agrochemical synthesis, the pump conveys organophosphates, chlorinated intermediates, and concentrated surfactant solutions that would quickly destroy lesser materials. The pump’s solids‑handling impellers can manage precipitated by‑products and catalyst fines that settle in storage tanks, making tank cleaning a fast and automated process.

• Pharmaceutical API Reactor Unloading: After synthesis, the reaction mass often contains strong acids, organic solvents, and precipitated product. The pump strips the reactor completely, even under vacuum, and its smooth internal surfaces prevent product hold‑up and cross‑batch contamination, meeting GMP cleanliness standards.
• Agrochemical Intermediates Transfer: Pesticide and herbicide precursors such as chlorinated pyridines, thiophosphoryl chloride, and alkylamines are highly corrosive and often toxic. Vertical sealless pumps in PVDF or PP handle these streams without risk of seal leak, protecting both operators and the environment.
• Polymerisation Loop Circulation: Maintaining uniform temperature and catalyst dispersion in a polymer reactor is critical for product quality. The pump circulates viscous, sometimes fouling fluids through external heat exchangers, and its wide‑open impeller passages avoid clogging from polymer particles.
• Solvent Recovery and Distillation Columns: Recovered solvents often contain residual acids and water, making them aggressive towards cast iron and stainless steel. The pump’s thermoplastic construction resists corrosion and can run dry when the sump is emptied, automating the recovery process without operator attendance.
• Acid and Caustic Bulk Storage Sumps: In tank farms storing 98% sulphuric acid, 50% sodium hydroxide, or concentrated hydrochloric acid, a vertical sealless pump can transfer from underground sumps or day tanks. Its inert wetted parts are immune to stress‑corrosion cracking that plagues stainless steel in chloride environments.
• Electronic‑Grade Chemical Delivery: Ultra‑high‑purity etching and cleaning solutions used in semiconductor fabrication cannot tolerate parts‑per‑billion metal ion contamination. Sealless pumps built from virgin, unpigmented PVDF or PFA provide the ionic cleanliness required while eliminating seal‑derived particulate generation.
• Wastewater Neutralisation Plants: Chemical plant wastes often contain mixed acids, alkalis, and heavy metal sludges. The pump can handle pH‑adjusted slurries with high solid content, transferring them from equalisation tanks to filter presses without the clogging or seal failure experienced by diaphragm or progressive cavity pumps.

Ready to Specify Your Vertical Sealless Pump?

Get a detailed quote tailored to your chemical process requirements. Our team will review your fluid composition, temperature, immersion depth, and flow head needs to recommend the ideal pump configuration.

Key Features of Vertical Sealless Pumps

The engineering behind a vertical sealless pump is a masterclass in simplicity and reliability. Every feature is designed to eliminate failure modes common in immersion pumps while reducing the total cost of ownership. At the core is the modular cantilever shaft assembly: a precision‑ground stainless‑steel shaft, often encased in a thermoplastic sleeve for complete chemical isolation, supported by a pair of heavy‑duty angular‑contact ball bearings located in a bearing housing high above the liquid. This arrangement ensures that the shaft rotates without any radial deflection, preserving the impeller’s concentricity and eliminating vibration. The bearing housing is lubricated for life and sealed against atmospheric moisture, so the pump requires no periodic greasing or oil changes, a significant advantage in remote or unmanned chemical storage facilities.

The hydraulic section is equally refined. Impellers are available in enclosed, semi‑open, and vortex designs, each optimised for specific fluid characteristics. Enclosed impellers deliver the highest efficiency for clean, low‑viscosity chemicals, while semi‑open designs resist clogging when occasional solids are present. Vortex impellers create a tornado‑like flow pattern that keeps most solids away from the impeller vanes altogether, making them ideal for stringy materials and heavy sludges. All impellers are dynamically balanced to ISO 1940 Grade 6.3 or better, ensuring smooth operation at speeds up to 3600 rpm. The pump column is manufactured from thick‑walled thermoplastic tube, providing rigidity and chemical resistance, and the discharge head can be oriented in any direction to simplify piping layouts.

• Modular Cantilever Shaft with Thermoplastic Sleeve: The stainless‑steel shaft is completely isolated from corrosive fumes and splashes by a thick, heat‑shrunk thermoplastic sheathing. Even if the process fluid generates aggressive vapour, the metallic core remains protected, preserving structural integrity and eliminating stress‑corrosion cracking.
• Lifetime‑Lubricated Upper Bearing Assembly: Angular‑contact ball bearings are pre‑loaded and sealed with non‑contact labyrinth seals on both sides. The bearing arrangement absorbs both the hydraulic thrust generated by the impeller and the weight of the shaft, requiring no maintenance over the pump’s entire service life.
• Three Impeller Geometry Options: Select from enclosed impellers for maximum hydraulic efficiency (up to 65%), semi‑open impellers for fluids with fibrous or crystalline solids, and recessed vortex impellers for sludges and slurries where particle integrity must be maintained. Each impeller is CNC‑machined to ensure repeatable performance.
• Thick‑Wall Thermoplastic Column Construction: The support column is fabricated from solid extruded thermoplastic, typically PP or PVDF, with wall thicknesses of up to 10 mm. This provides the bending stiffness needed to resist vibration while maintaining full chemical resistance without any metallic reinforcement that could corrode.
• 360‑Degree Rotatable Discharge Head: The discharge nozzle is mounted on a flanged or union connection that can be oriented to any direction before final tightening. This feature accommodates any plant piping layout without the need for additional elbows or flexible hoses, reducing fitting count and flow resistance.
• Adjustable Impeller Clearance: A threaded bearing housing or external shim system allows the impeller‑to‑volute gap to be set precisely during installation. Maintaining the correct clearance compensates for thermal expansion and wear, preserving pump efficiency and preventing contact between rotating and stationary parts.
• Static O‑Ring Sealing Throughout: Every stationary joint in the pump, including the column‑to‑volute and discharge‑head connections, is sealed with chemically resistant FKM, EPDM, or FFKM O‑rings. Static seals are inherently more reliable than dynamic seals, providing a bubble‑tight barrier that withstands both pressure and vacuum.
• Direct‑Drive Motor Coupling: The shaft connects directly to an IEC‑frame motor via a rigid coupling or is machined as a single‑piece motor spindle. Eliminating the intermediate bearing pedestal and flexible coupling reduces the pump’s overall height and weight, making it easier to install on tall reactors and deep sumps.

Technical Specifications and Performance Envelope

A vertical sealless pump destined for specialty chemical service must operate within a defined hydraulic and mechanical window that balances efficiency, reliability, and chemical compatibility. The pump family discussed here covers a flow range from as low as 0.5 m³/h up to around 120 m³/h, with differential heads reaching 45 metres per stage. This wide operating envelope is achieved by offering multiple impeller diameters and motor speeds, allowing the pump to be sized for low‑flow dosing applications as well as high‑volume transfer duties. The pump's characteristic curve is steep and stable, meaning that even significant changes in system pressure result in only modest flow changes, a behaviour that prevents hunting and surging in automatic control loops.

Material selection defines the pump’s pressure and temperature limits, and the specification matrix is designed to provide clear guidance. A PP pump, for example, can typically handle fluids up to 90 °C continuously and is suitable for a wide family of acids, bases, and saline solutions. For solvents, mixed acids containing nitric acid, and higher temperatures up to 120 °C, PVDF becomes necessary. For extreme chemical environments, including hot concentrated sulphuric acid, bromine, or strong oxidisers, special grades such as ETFE or PFA may be specified. The motor is selected based on the specific gravity of the fluid; higher‑density chemicals require more powerful motors to achieve the same head and flow, and our engineering team always includes a service factor margin of at least 1.15 to accommodate batch‑to‑batch variation.

• Flow Range: 0.5 m³/h to 120 m³/h under standard 50 Hz operation. The pump can be adapted to 60 Hz motors to extend the maximum flow further; higher speeds increase flow and head proportionally but require re‑evaluation of NPSH margins and material stress limits.
• Differential Head: Up to 45 metres of water column (approximately 4.5 bar) from a single‑stage design. For applications requiring higher discharge pressure, two pumps can be staged in series, or a larger‑diameter impeller can be fitted, subject to motor power and column structural limits.
• Motor Power: Available from 0.37 kW for small dosing pumps up to 15 kW for high‑flow, high‑specific‑gravity chemicals. Motors are available in IE3 and IE4 efficiency classes, with options for flame‑proof (Exd), increased‑safety (Exe), and non‑sparking (Exn) enclosures to suit zone‑classified areas.
• Maximum Operating Temperature: 90 °C continuous for polypropylene (PP) wetted parts; 120 °C for PVDF wetted parts. Intermittent temperature excursions of +15 °C are permissible for short durations such as steam‑out or hot CIP cycles, provided the pump is not operating during the peak temperature exposure.
• Immersion Depth: Standard column lengths provide immersion depths of 600 mm, 800 mm, and 1000 mm. Special orders can extend this to 3400 mm by adding a suction pipe extension that fills with liquid by gravity, allowing the pump to empty deep pits and storage tanks without requiring an excessively long shaft.
• NPSHr (Net Positive Suction Head Required): Typically less than 1 metre for flow rates up to 50 m³/h. This extremely low NPSHr is achieved by the fully flooded suction and the optimised impeller eye geometry. It allows the pump to operate safely with boiling or near‑boiling liquids without cavitation erosion.
• Solids Passage: Vortex impeller models can pass spherical solids up to 25 mm in diameter. Semi‑open impeller models can handle fibrous and stringy solids up to 15 mm. The volute casing incorporates a large tangential discharge that prevents solids accumulation and enables easy flushing during CIP cycles.
• Noise Level: Under normal operation, sound pressure levels are below 75 dB(A) at one metre, complying with occupational health guidelines. The submerged impeller and encapsulated bearing housing act as natural acoustic dampers, making the pump suitable for installation in occupied process buildings.

Why Choose HIS Pumps and Systems

Selecting a pump manufacturer for specialty chemical applications is a decision that impacts plant safety, product quality, and operational budgets for years to come. HIS Pumps and Systems brings decades of domain‑specific expertise to every project, combining deep material science knowledge with practical field experience in specialty chemical plants. Unlike general‑purpose pump suppliers, HIS focuses exclusively on seal‑less thermoplastic pumping technologies, which means our engineering team lives and breathes the nuances of polymer processing, chemical compatibility, and hydraulic optimisation required for aggressive media. Our manufacturing facilities are equipped with state‑of‑the‑art CNC machining centres, automated welding stations, and a dedicated test bay where every pump is hydrostatically pressure‑tested and run on a calibrated test loop before dispatch. The result is a level of quality assurance that gives plant operators confidence to install our pumps in the most demanding safety‑critical loops without hesitation.

Beyond the hardware, HIS Pumps and Systems provides end‑to‑end application engineering support that starts with a detailed fluid questionnaire and does not end until the pump is commissioned and running to specification. We assist with material selection by cross‑referencing your process stream against an extensive database of chemical resistance data, including the effects of concentration, temperature, and mixed‑phase exposure. If your process involves a novel solvent blend or an unusual catalyst system, our laboratory can arrange immersion coupon testing to validate long‑term compatibility before a single order is placed. This consultative approach has made HIS the preferred partner for pharmaceutical API manufacturers, agrochemical formulators, and electronic‑grade chemical producers across the region.

• Exclusive Focus on Sealless Thermoplastic Pumps: Unlike manufacturers who divide their attention across dozens of pump types, HIS dedicates its entire engineering resource to perfecting vertical and horizontal sealless thermoplastic designs. This specialisation yields product maturity, a deep spare‑parts inventory, and rapid technical responses to unusual fluid challenges.
• In‑House Chemical Compatibility Testing: HIS maintains a well‑equipped materials laboratory where customer‑supplied fluid samples can be tested against candidate polymers under controlled temperature and stress conditions. Results are documented in a formal compatibility report, eliminating guesswork and ensuring the selected pump material will survive the intended service life.
• Factory Performance Testing on Every Pump: Before any pump leaves the factory, it undergoes a full hydraulic performance test that confirms flow, head, power draw, and vibration levels against the published curve. A certified test report is available with every shipment, giving plant engineers documented proof of performance for their equipment qualification files.
• Rapid Delivery and Regional Inventory: HIS stocks a comprehensive inventory of finished pumps and critical spare components at strategic regional warehouses. For standard configurations, delivery times as short as two weeks are achievable, ensuring that plant shutdowns and turnaround projects are not delayed by long lead‑time equipment.
• On‑Site Commissioning and Training: A HIS service engineer can be present during initial pump commissioning to verify installation, alignment, and controls integration. Operator training sessions cover safe start‑up procedures, dry‑run limitations, and troubleshooting, reducing the likelihood of early‑life failures caused by unfamiliarity.
• Life‑Cycle Support and AMC Programmes: HIS offers annual maintenance contracts (AMCs) that include periodic pump health checks, bearing vibration analysis, and impeller clearance adjustments. These programmes are designed to catch wear trends early and schedule preventative interventions during planned outages, rather than reacting to unexpected breakdowns.
• Proven Track Record in Regulated Industries: HIS pumps are installed in facilities governed by FDA, EMA, and REACH regulations, where documentation, material traceability, and change control are mandatory. Our quality management system supports the full supply‑chain transparency that pharmaceutical and fine chemical manufacturers demand from their equipment suppliers.

Talk to Our Pump Experts Today

Confused about material selection or hydraulic sizing for your specialty chemical application? Speak directly with a senior applications engineer at HIS Pumps and Systems. We will analyse your process data and recommend the optimal vertical sealless pump configuration, usually within one business day. There is no cost for this consultation, and you will receive a detailed proposal including a performance curve, GA drawing, and commercial quotation.

Material Compatibility for Specialty Chemical Service

Material selection is the single most consequential decision when specifying a pump for specialty chemicals, because even the best hydraulic design will fail prematurely if the wetted components are attacked by the process fluid. The vertical sealless pump family offered by HIS is available in four primary thermoplastic grades, each engineered for a distinct chemical resistance envelope. Polypropylene (PP) is the most economical option and delivers outstanding resistance to aqueous solutions of most mineral acids, alkalis, and saline brines up to 90 °C. It is widely used for sodium hydroxide, hydrochloric acid, phosphoric acid, and ferric chloride solutions. However, PP swells and softens in contact with many organic solvents, especially aromatic hydrocarbons and chlorinated solvents, so it must not be used for those streams.

For solvent‑heavy processes and higher‑temperature acid mixtures, polyvinylidene fluoride (PVDF) is the material of choice. PVDF exhibits near‑universal resistance to hydrocarbons, halogenated solvents, alcohols, and esters, while also tolerating continuous exposure to sulphuric acid concentrations up to 98% at temperatures approaching 120 °C. It is the default polymer for pharmaceutical solvent recovery, electronic‑grade chemical delivery, and any service where product purity is paramount. For extreme conditions involving hot concentrated nitric acid, oleum, or bromine, speciality fluoropolymers such as ethylene tetrafluoroethylene (ETFE) or perfluoroalkoxy (PFA) can be employed. These materials approach the chemical inertness of PTFE but with superior mechanical strength, allowing them to be used for pump columns and impellers without cold‑flow deformation. HIS engineers will guide you through a formal compatibility assessment, considering not only the main chemical but also trace impurities, cleaning agents, and potential upset conditions.

• Polypropylene (PP): The workhorse material for aqueous acids and alkalis. Excellent resistance to hydrochloric acid (all concentrations), sulphuric acid (up to 70%), sodium hydroxide (up to 50%), and most plating baths. Maximum continuous service temperature is 90 °C. Not suitable for aromatic or chlorinated hydrocarbons, which cause rapid softening and stress cracking.
• Glass‑Reinforced Polypropylene (GFR‑PP): A 20‑30% glass‑fibre‑filled variant that doubles the tensile strength and stiffness of unfilled PP, while retaining most of its chemical resistance. Recommended when the pump must handle higher discharge pressures or when the column is exceptionally long and needs additional rigidity to resist flow‑induced vibration.
• Polyvinylidene Fluoride (PVDF): A high‑performance fluoropolymer with exceptional resistance to mineral and organic acids, aliphatic and aromatic hydrocarbons, halogenated solvents, alcohols, and esters. PVDF maintains its mechanical properties up to 120 °C and is inherently flame‑retardant and UV‑resistant. It is the preferred material for pharmaceutical solvent streams, mixed‑acid etchant baths, and high‑purity chemical delivery systems where leachable metal ions must be below parts‑per‑billion levels.
• Ethylene Tetrafluoroethylene (ETFE): A tough, high‑strength fluoropolymer that bridges the gap between PVDF and fully fluorinated materials. ETFE offers outstanding resistance to strong oxidising acids, including hot concentrated nitric acid, and can handle repeated thermal cycling without fatigue cracking. It is often specified for reactor off‑loading pumps in nitration and sulphonation processes.
• Perfluoroalkoxy Alkane (PFA): The ultimate material for ultra‑high‑purity and extreme chemical environments. PFA is fully fluorinated like PTFE, meaning it resists virtually all chemicals except molten alkali metals and elemental fluorine at elevated temperatures. Its melt‑processability allows it to be injection‑moulded into complex impeller shapes, providing both chemical inertness and high hydraulic efficiency.
• Ultra‑High Molecular Weight Polyethylene (UHMW‑PE): When the application involves abrasive slurries with moderate chemical aggression, UHMW‑PE provides the best combination of wear resistance and impact strength. It is ideal for pumping catalyst‑laden solutions, crystalliser slurries, and mining reagents at temperatures up to 80 °C.
• O‑Ring and Gasket Elastomer Selection: The static seals in the pump are as critical as the structural polymer. HIS offers FKM (Viton) for general chemical service up to 200 °C, EPDM for hot water and polar solvents, and FFKM (perfluoroelastomer) for the broadest chemical resistance. The correct elastomer is chosen after reviewing the complete chemical composition, including any cleaning agents and steam‑out procedures.
• Metallic Shaft and Hardware Options: For applications where the thermoplastic sleeve provides the primary chemical barrier but the shaft core must resist specific corrosive vapours, the stainless‑steel shaft can be upgraded to duplex stainless steel (e.g., 2205), Hastelloy C‑276, or titanium. External fasteners are supplied in 316 stainless steel or coated carbon steel as standard, with full traceability documentation.
• Conductivity Modifications for ATEX Compliance: Standard thermoplastics are electrically insulating and can accumulate static charges when pumping low‑conductivity solvents. HIS offers carbon‑filled conductive grades of PP and PVDF that safely dissipate static electricity to ground, meeting the requirements of ATEX Directive 2014/34/EU for equipment used in potentially explosive atmospheres.

Vertical Sealless Pump Selection Guide for Specialty Chemicals

Choosing the correct vertical sealless pump configuration requires a methodical approach that begins with a complete characterisation of the process fluid and operating conditions. The selection process is not simply about matching a flow and head requirement to a pump curve; it also demands careful consideration of the chemical aggressiveness, solids content, temperature, vapour pressure, and the mechanical constraints of the installation site. Our engineers follow a structured workflow that starts with a chemical compatibility screening, then proceeds to hydraulic sizing, material selection, motor and bearing specification, and finally instrumentation and control integration. The goal is to deliver a pump that is not only technically correct on day one but will continue to perform reliably as the process evolves and as the plant cycles through different products and cleaning regimes.

A common pitfall in pump selection is underestimating the effect of fluid specific gravity on power consumption. Many chemicals handled in specialty plants have densities well above water: 98% sulphuric acid has a specific gravity of 1.84, 50% sodium hydroxide is 1.53, and bromine is 3.12. The hydraulic power required is directly proportional to fluid density, so a pump sized for water will be severely underpowered when pumping a heavy chemical. HIS provides a detailed data sheet that prompts the user to supply all the critical parameters, including minimum and maximum operating temperatures, the presence of any abrasive solids, and the NPSH available at the pump suction. This information is used to verify that the selected pump operates within its safe hydraulic and mechanical limits across the entire expected operating envelope. Our application engineers are available to review your data sheet and identify any potential issues before an order is placed, saving costly rework and field modifications.

• Step 1: Fluid Characterisation: List every chemical present in the stream, including trace impurities, cleaning solutions, and possible decomposition products. Note the concentration range, pH, and any known incompatibilities. This information is used to short‑list candidate polymers (PP, PVDF, ETFE, PFA) and elastomers for the application.
• Step 2: Define Operating Conditions: Specify the required flow rate (in m³/h or L/min), total dynamic head (in metres of liquid column), fluid temperature range, and specific gravity at pumping temperature. Also note whether the pump will run continuously or in intermittent batch mode, as this affects bearing life calculations.
• Step 3: Assess Solids and Viscosity: If the fluid contains suspended solids, measure the particle size distribution, hardness, and concentration (wt%). For fluids with viscosity above 100 cP, the pump performance must be corrected using established viscosity correction factors. Choose between enclosed, semi‑open, or vortex impeller based on solids loading and required efficiency.
• Step 4: Determine Immersion Depth and Column Length: Measure the distance from the tank nozzle or sump cover plate to the lowest liquid level that must be pumped. Add a safety margin to ensure the impeller remains fully submerged under all normal and upset conditions. Standard column lengths are 600, 800, and 1000 mm; longer requirements can be met with suction extensions up to 3400 mm.
• Step 5: Verify NPSH Margin: Calculate the net positive suction head available (NPSHa) based on liquid level above the impeller, atmospheric pressure, fluid vapour pressure, and suction line losses. The selected pump must have an NPSHr at least 0.5 m lower than NPSHa across the entire flow range. The deep‑submergence design of vertical sealless pumps typically makes this margin easy to achieve.
• Step 6: Select Motor and Area Classification: Choose the motor power by multiplying the hydraulic power by the fluid specific gravity and a service factor of at least 1.15. Select the frame size, enclosure type (TEFC, flame‑proof Exd, increased‑safety Exe), and voltage to match the plant’s electrical infrastructure. For VFD operation, specify a variable‑torque inverter‑duty motor with reinforced winding insulation.
• Step 7: Define Instrumentation and Controls: Decide whether the pump requires a local start/stop station, a run‑dry protection relay, a variable frequency drive for flow control, or integration into a plant DCS via 4‑20 mA signals. HIS can supply pre‑wired control panels with all necessary interlocks and alarms to make commissioning fast and error‑free.
• Step 8: Review Installation Constraints: Check the available headroom above the tank for motor and discharge piping, the tank nozzle bore diameter, and any structural loading limits on the tank roof. HIS provides dimensional general arrangement drawings and weight estimates early in the enquiry stage so that civil and mechanical interfaces can be verified before procurement.
• Step 9: Final Data Sheet Review and Approval: Once all parameters are compiled, the HIS application engineer generates a completed technical data sheet that lists the pump model, materials, hydraulic performance curve, motor details, and scope of supply. The data sheet is reviewed and signed off by both HIS and the customer’s engineering team, forming the contractual basis for manufacture and testing.