How to Select a Centrifugal Pump: Duty Point to Datasheet

Specific speed sets the impeller type. The standard (ISO 2858, ISO 5199, ANSI B73.1 or API 610) sets what you are allowed to expect from the casing and bearing frame. NPSH margin is a ratio against NPSHr, not a fixed meter. Operating band matters more than the rated point. Viscosity in the 20 to 40 cSt band is where the water curve stops applying. The seal is chosen from the liquid, not the pump.

A centrifugal pump duty point is a required flow paired with a total dynamic head, and any pump whose head-versus-flow curve passes through that coordinate can, at rated speed, meet it in principle. That is what the duty point fixes and the whole of it. Between the coordinate on an RFQ and the datasheet a supplier can quote from sits a chain of seven decisions that flow and head alone do not settle: impeller geometry, casing standard, NPSH margin, position of the rated point in the operating band, viscosity and derating from the water curve, shaft sealing and the wetted materials that go with it, and the datasheet fields that let a supplier price the pump without guessing.

The reader assumed here is a procurement or project engineer holding a centrifugal pump datasheet whose duty point was fixed upstream. Specific speed and shaft speed read the impeller shape off the duty point. Four standards, ISO 2858, ISO 5199, ANSI B73.1 and API 610, each constrain a different thing. The Hydraulic Institute publishes NPSH margin as a ratio by service. ANSI/HI 9.6.3 sets preferred and allowable operating regions. ANSI/HI 9.6.7 corrects the water curve above 20 to 40 centistokes. API 682 sorts shaft seals by category. The datasheet then carries every one of those decisions, field by field.

• Specific speed. The dimensionless number from the duty point sets impeller geometry: radial, mixed flow, or axial.
• Which standard applies. ISO 2858 fixes dimensions, ISO 5199 fixes mechanical design, API 610 raises the whole bar.
• NPSH margin. NPSHr as published is a 3 percent head-drop point, not zero cavitation, so size margin by ratio.
• Operating band. The Preferred Operating Region runs 70 to 120 percent of BEP flow per ANSI/HI 9.6.3.
• Viscosity correction. Correction cuts head, flow, and efficiency simultaneously and raises motor power; the threshold sits in the 20 to 40 cSt band.
• Seal arrangement. API 682 organizes seals and flush plans; a sealless pump (magnetic drive or canned motor) removes the interface.

• 16 bar ISO 2858 casing rating for horizontal end-suction frames
• 3% head-drop point that defines a published NPSHr per ANSI/HI 14.6
• 11,000 US-unit suction specific speed threshold above which part-load recirculation risk rises
• 70 to 120% of BEP flow, the Preferred Operating Region per ANSI/HI 9.6.3
• 80 to 110% of BEP flow, the API 610 band the rated point must sit inside
• 20 to 40 cSt viscosity range above which the water performance curve stops applying

• Abstract
• Key Takeaways
• The duty point is an input, not an answer
• Specific speed decides the impeller before you do
• Which standard actually governs the pump you are buying
• NPSH margin is a ratio, not a fixed number
• The operating band matters more than the rated point
• When the water performance curve stops applying
• The seal follows the liquid, and the datasheet follows both
• Frequently Asked Questions
• Conclusion
• References

A centrifugal pump duty point is a single coordinate on the pump's head-flow curve: a required flow rate paired with the total dynamic head that must be generated at that flow. It fixes where the pump lands on its own curve. It does not fix the pump.

A duty point fixes one coordinate on one curve and leaves five of those seven decisions open the moment it is agreed: impeller geometry, casing standard, suction margin, operating band, and materials. ISO 2858 rates end-suction frames to 16 bar and ANSI/HI 9.6.3 governs the operating band, so both follow the service class rather than flow and head (Hydraulic Institute, 2024b).

The duty point pins one point on one curve. Any centrifugal pump whose head-versus-flow curve passes through that point can, in principle, meet the duty at rated speed. A stated NPSHr at that flow travels with it. That is the whole of what flow and head alone determine. Two engineers can hold the same duty point and choose very different pump configurations. Selection is choosing among the candidates against additional criteria, not deriving one from the numbers on the RFQ.

Five specifications remain unfixed after the duty point is agreed. Each is chosen against a different criterion, and each belongs on the datasheet.

• Impeller geometry. Radial, mixed-flow, or axial. Governed by specific speed, which is calculated from the duty point and shaft speed but not implied by the duty alone (Karassik et al., 2008).
• Casing standard. ISO 2858 constrains frame dimensions and rates end-suction pumps to 16 bar; ISO 5199 constrains mechanical design; ANSI B73.1 constrains both for chemical service; API 610 (dual-numbered as ISO 13709) applies to refinery service (International Organization for Standardization, 1975, 2002; American Society of Mechanical Engineers, 2012; American Petroleum Institute, 2021). The standard is chosen from the service class, not the flow and head.
• Suction conditions. NPSH available is a plant-side number the pump does not know. The margin over NPSHr is the buyer's responsibility.
• Operating band. ANSI/HI 9.6.3 defines a Preferred Operating Region around the best efficiency point and a wider Allowable Operating Region; the boundaries are manufacturer-defined and specific-speed dependent, not universal numbers (Hydraulic Institute, 2024b). The rated duty point should sit inside the preferred region across the plant year, not only at nameplate conditions.
• Materials of construction. The wetted-side inventory, from fasteners through seal faces, is chosen from the fluid, not the flow.

None of the five reduces to flow and head. Each has its own criterion, its own standard, and its own line on the datasheet.

Specific speed (Ns) is a dimensionless number computed from the duty point that predicts which centrifugal pump impeller shape will do the work efficiently. Fix the flow, the head, and the shaft speed, and Ns has largely chosen the geometry for you before the datasheet is drawn. That is why impeller geometry belongs in front of the pump curve, not after.

Two conventions coexist and they are not interchangeable. US customary Ns uses gallons per minute and feet: Ns = N × Q^0.5 / H^0.75, with N in rpm, Q in US gpm, and H in feet, evaluated per stage. Metric Nq uses cubic meters per second and meters: Nq = N × Q^0.5 / H^0.75, per stage. The two differ by roughly a factor of 51.6, so a metric Nq of 40 is a US Ns near 2,064. Quoting a band without naming the convention is the single most common error in specific-speed work. Compute at the best efficiency point flow of the centrifugal pump, not at run-out.

Commonly cited bands, per Karassik's Pump Handbook, are roughly 500 to 4,000 US Ns for radial impellers, 4,000 to 10,000 for mixed-flow, and 10,000 to 15,000 for axial (Karassik et al., 2008). These are per-stage guidelines, not a standard, and where an application lands near a boundary the single-stage/multi-stage decision matters more than the impeller shape.

A radial impeller develops high head per stage at low flow; its channels are narrow and the vanes discharge nearly perpendicular to the shaft. A mixed-flow impeller combines radial and axial velocity components, trading some head for more flow. An axial impeller, a propeller inside a bowl, moves high flow at low head per stage.

Suction specific speed (Nss) uses NPSHr in place of head: Nss = N × Q^0.5 / NPSHr^0.75, in matching units. It predicts suction-side behavior, not impeller shape, and is a separate number from Ns. A high Nss, above about 11,000 US units, means the suction eye has been opened to reduce NPSHr, and that same geometry narrows the stable operating window around BEP (Turbomachinery Laboratory, Texas A&M University, n.d.). That threshold is not arbitrary: a 1982 study of refinery-pump reliability first tied failure frequency to suction specific speed and put the number at 11,000 (Hallam, 1982). A high Nss centrifugal pump can meet the datasheet on paper and still recirculate, vibrate, or cavitate at partial load (Turbomachinery Laboratory, Texas A&M University, n.d.). Verify Nss on the curve you accept, not only NPSHr.

Four standards get named on the same catalog line as if they were substitutes: ISO 2858, ISO 5199, ANSI B73.1, and API 610 (dual-numbered ISO 13709). They are not substitutes. Each constrains a different thing about a centrifugal pump, and knowing which one applies is the difference between a supplier claim you can hold and one you cannot.

ISO 2858 is a dimensional standard for horizontal end-suction centrifugal pumps rated at 16 bar, published by the International Organization for Standardization; it fixes frame sizes and duty designations so any conforming pump drops into the same footprint (International Organization for Standardization, 1975). That is what "conformance" means for that document, and that alone.

The two are written to be layered. ISO 2858 governs the envelope; ISO 5199 governs the mechanicals inside it. A pump that meets ISO 2858 alone is interchangeable dimensionally but says nothing about shaft stiffness, bearing life, or hydrostatic testing. Adding ISO 5199 covers the design class, and it also applies to centrifugal pumps whose dimensions are not ISO 2858 at all (International Organization for Standardization, 1975, 2002).

ASME B73.1 (still commonly called ANSI B73.1) is the North American answer to the same problem, and it does both jobs in one document: dimensions and mechanical requirements for horizontal end-suction pumps in chemical process service. Where ISO 2858 and ISO 5199 are layered, B73.1 covers that class in a single document. A B73.1 pump and an ISO 2858 pump are not dimensionally interchangeable; the two documents pick different frame sizes.

API 610 (12th edition), dual-numbered ISO 13709, is the refinery-grade standard, and it is materially heavier than the three above (American Petroleum Institute, 2021). It sets allowable nozzle loads, mandates specific pump types (OH2, BB1, BB2 and others), demands documented mean time between failures, and pulls in API 682 for shaft sealing. Naming it in a specification changes the price of the pump, the paperwork required, and the vendor pool that can bid.

Conformance says a pump was built to a spec. It does not say the pump suits your duty. A B73.1 pump can be ordered in a size that lives at 40 percent of BEP on your curve. An API 610 pump can be selected with an NPSH margin too thin for a summer suction temperature. The standard is a floor for construction; the duty point, BEP position, NPSH margin, and seal plan are still the specifier's call, and conformance to any of them does not change that.

A duty point fixes a coordinate on the curve, not the pump. The liquid, its temperature and viscosity, the solids it carries, the seal arrangement, and the connection standard all still need an answer before a centrifugal pump can be quoted with confidence. Bring what you have settled and what is still open, and talk to the factory about which pump in the range actually fits the duty.

Cavitation destroys a centrifugal pump from the inside. The usual defense is a fixed cushion above NPSHr, quoted as 0.5 meter in metric practice and as 3 feet in US practice. Those are two different rules of thumb rather than one converted figure, and both are weaker instruments than they look. The instrument that actually protects the pump is a ratio, and it varies by service.

NPSHa is a property of the installation: atmospheric pressure at the suction flange, minus vapor pressure, minus friction and lift, expressed in meters of head. It is fixed before a pump is chosen, because it belongs to the piping, the elevation and the fluid. NPSHr is a property of the pump, measured by the manufacturer on a test loop and printed on the curve. ANSI/HI 14.6 defines that published NPSHr as the NPSH3 point: the suction head at which the first-stage total head has already dropped by three percent (Hydraulic Institute, 2022). Cavitation has been ongoing well before that.

NPSHr is not the onset of cavitation. It is a measurable operating point past which the pump is losing head, no more and no less. Full-cavity inception can begin at two to twenty times NPSH3 depending on suction energy (Grist, 2023). A universal 0.5 meter cushion is adequate for a small water booster and negligent for a boiler feed pump; the two carry different suction energy and different consequences from a partial cavity. What the Hydraulic Institute publishes instead is a service-keyed ratio of NPSHa to NPSHr, backed by an absolute floor in meters.

ANSI/HI 9.6.1 (2024) Table A gives single ratios by service: water and general building at 1.0 to 1.1 or a 0.6 meter floor; chemical process at 1.1 to 1.2 above a 0.6 to 1.0 meter floor; petroleum and hydrocarbon at 1.1 with a 1.0 meter absolute floor; boiler feed under 250 kW per stage at 1.3 (Hydraulic Institute, 2024a). Above those bands lies the territory HI's NPSHa Margin Work Group covers case by case, and where a centrifugal pump for high-energy service needs an engineered margin rather than a tabled one.

Five factors move a duty out of the tabled band, and any one of them is sufficient to trigger case-by-case analysis.

• High suction energy. Large impeller eyes, high flow, high speed. The Hydraulic Institute classifies energy by eye tip speed and eye area.
• High suction specific speed (Nss). Above roughly 11,000 US units the eye or inducer geometry gains part-load recirculation risk, and the tabled ratio stops covering it.
• Hydrocarbons and other low-surface-tension liquids. Cavitation nuclei form at lower thresholds; the petroleum row of Table A already carries part of the correction, but only part.
• Liquids near their boiling point. Boiler feed, hot condensate, LPG. Any local pressure drop crosses vapor pressure quickly.
• Operation away from BEP. Off best efficiency, NPSHr rises on both flanks and the impeller develops recirculation cavitation.

Any centrifugal pump specified on the water-service ratio and then trimmed, sped up or run off-duty inherits a margin that no longer matches the number on the datasheet.

Datasheets quote one flow and one head. The pump lives across a band of flows, and the width of that band is a choice, not a fact. Selecting a centrifugal pump means putting the rated point on the curve where the hydraulics are quiet, then confirming the process will not push it into the noisy parts under turndown, startup, or upset.

Best efficiency point (BEP) is the flow at which the impeller loads the volute symmetrically. Efficiency peaks there because internal losses (recirculation at the eye, disk friction, hydraulic incidence at the vanes) all minimize together, and the net radial thrust on the shaft is close to zero. Move the pump off BEP and the volute pressure field goes asymmetric; the impeller starts to see a hydraulic side load.

Three things move a duty point off BEP after commissioning: process turndown or throttling, a system curve that shifts as strainers foul or a tank drains, and parallel operation where one machine ends up carrying more than its share.

ANSI/HI 9.6.3 defines two bands around BEP (Hydraulic Institute, 2024b): the Preferred Operating Region (POR), where radial thrust and life are near their best, and the wider Allowable Operating Region (AOR), which the standard leaves manufacturer-defined and specific-speed-dependent with no universal lower bound. API 610 layers a tighter rule: the rated point must fall inside 80-110% of BEP (American Petroleum Institute, 2021).

Off-band operation is measured in mechanism damage, not efficiency points. Below the POR, radial load rises steeply, shaft deflection at the seal faces grows, and suction recirculation at the impeller eye begins; L10 bearing life falls with the cube of load, and seal faces lose flatness. Above 120% of BEP, discharge recirculation and cavitation onset take over, with NPSH required climbing faster than the curve suggests. Vibration signatures at 1x and vane-pass frequencies rise in both directions.

The geometry has one consequence worth naming: a centrifugal pump chosen exactly at BEP for one design flow spends its life away from BEP the moment the process turns down. Size for the band the plant will actually run, not the number on the requisition.

Every performance curve printed on a datasheet is a water curve. The test loop that generated it used clear cold water. Read it directly for a viscous liquid and the motor you order will be undersized, which is the kind of mistake that only becomes visible on the day the pump lands on the pad.

The Hydraulic Institute treats the published water curve as a defensible reference roughly up to kinematic viscosities in the range of 20 to 40 centistokes at the pump inlet, above which the correction factors set out in ANSI/HI 9.6.7 stop being negligible and belong in every viscous-service selection review (Hydraulic Institute, 2021). The band is not a bright line. The exact viscosity at which corrections stop being optional depends on impeller size, BEP flow and Reynolds number in the impeller passage, so a small centrifugal pump crosses the threshold sooner than a large one. Cold water, diesel and typical ambient hydraulic oil sit inside the band; heavy fuel oil, glycerin, cold crude and molasses do not.

ANSI/HI 9.6.7 (2021) gives three factors, applied to the water curve at the duty point: CQ on flow, CH on head, and Cη on efficiency. All three are below 1.0. A centrifugal pump delivers less flow at less head and less efficiently than the water curve suggests. Absorbed shaft power rises at the same duty, because the hydraulic output has fallen while the disc-friction and viscous losses inside the impeller passage have not. That is the motor-sizing consequence, and it is the number that costs money after the pump arrives. A motor sized from the water curve for a viscous duty will trip on overload, and the pump itself may run outside the range its bearings were designed for.

Three more derating cases the water curve does not cover, each with its own method. Entrained gas above a few percent by volume drops head sharply and can break prime. Solids concentration and abrasiveness change wear rates and effective clearances. Hot service reduces NPSH available through vapor-pressure rise (Sulzer Pumps, 2010). Treat each as a separate check against the supplier's operating envelope, not a viscosity-style formula.

A centrifugal pump does not tell you how to seal it. The liquid does. Its temperature, its hazard, and the consequence of a leak set the envelope the pump has to accept.

A mechanical seal is a pair of flat faces, one rotating with the shaft and one stationary in the gland. It leaks a small controlled amount by design and covers almost every service duty. A sealless pump (magnetic drive or canned motor) removes the shaft penetration and with it the leak path. It costs more, tolerates less dry running and fewer solids, and removes an inspection surface. Choose sealless where the liquid is toxic, carcinogenic, or fugitive-emissions regulated (American Petroleum Institute, 2014); choose a mechanical seal where a monitored small leak is acceptable and you need the wider solids and viscosity envelope.

API 682 is the reference for shaft sealing in centrifugal pumps and rotary pumps, first written for refinery service and now applied far beyond it (American Petroleum Institute, 2014). It sets requirements for the seal itself and standardizes the piping that keeps the faces in their operating window. That plumbing is the numbered seal-plan library (Plan 11 upward), covering discharge-return flushes, external clean flushes, and pressurized barriers for double seals in hazardous service. There are dozens; the correct plan falls out of the fluid class (clean cold, dirty, hot flashing, hazardous, low-boiling), not the pump model.

API 682 is co-published as ISO 21049 and sorts mechanical seals into three categories tied to the seal chamber they seat in: Category 1 for non-API 610 process pumps whose chambers meet ASME B73.1 or ISO 3069, and Categories 2 and 3 for API 610 pumps, with Category 3 written to a more stringent set of design and testing requirements (American Petroleum Institute, 2014).

A supplier cannot price a pump from a flow and a head alone, and most of the delay between an enquiry and a quotation is spent asking for fields that could have been sent in the first message. What follows is the minimum a centrifugal pump quote needs.

A field the datasheet omits is a field the supplier will guess or query. Fill them once, and correctly, and the specification chain that led here pays for itself.

• NPSHa. A property of the installation: atmospheric pressure at the suction flange, minus vapor pressure, minus friction and lift, expressed in meters of head.
• NPSHr. A property of the pump, measured by the manufacturer on a test loop and printed on the curve.
• NPSH3. The point per ANSI/HI 14.6 at which the first-stage total head has dropped by three percent; a published NPSHr equals NPSH3.
• BEP. Best efficiency point. The flow at which the impeller loads the volute symmetrically and net radial thrust on the shaft is close to zero.
• POR. Preferred Operating Region. Runs 70 to 120 percent of BEP flow per ANSI/HI 9.6.3, where radial thrust and bearing and seal life are near their best.
• AOR. Allowable Operating Region. Roughly 40 to 120 percent of BEP, manufacturer-defined and specific-speed dependent, with no universal lower bound.
• Ns. Specific speed. A dimensionless number computed from the duty point that predicts which impeller shape will do the work efficiently.
• Nss. Suction specific speed. Uses NPSHr in place of head; predicts suction-side behavior, not impeller shape.
• CQ, CH, Cη. ANSI/HI 9.6.7 correction factors on flow, head, and efficiency applied to the water curve for viscous service.

Centrifugal pumps move liquid through a system when the fluid is reasonably clean, low in viscosity, and needed at a fairly steady flow and head. Typical services include municipal and building water supply, HVAC circulation and chilled water loops, cooling water, chemical process transfer, boiler feed, and hydrocarbon fractionation and pipeline booster duty.

The main disadvantage is that its performance is coupled to the fluid: the published curve is a water curve, and head, flow, and efficiency all fall as viscosity climbs. Centrifugal pumps also struggle to self-prime, dislike sustained operation far from best efficiency point, and require careful NPSH accounting on the suction side to avoid cavitation damage.

By impeller geometry there are three types: radial, mixed flow, and axial. The choice is not a preference; it is set by specific speed, a dimensionless number calculated from the duty point. Radial impellers suit low-flow, high-head service; mixed-flow impellers suit medium flow and medium head; axial impellers suit high-flow, low-head service.

A rotating impeller adds kinetic energy to the liquid at the eye, and the surrounding volute or diffuser slows the flow, converting that kinetic energy into pressure at the discharge. Shinjo's operating-principle page treats the mechanism in depth; the selection chain assumes it and picks up from the duty point.

NPSH margin is a ratio against published NPSHr, not a universal figure, because NPSHr is a 3 percent head-drop value and not the onset of cavitation. Typical ANSI/HI 9.6.1 bands run 1.0 to 1.1 for open water systems, 1.1 to 1.2 for chemical process, and roughly 1.3 for boiler feed under 250 kW per stage. High-energy and high suction specific speed service sits above those tabled bands and needs an engineered margin rather than a looked-up one.

ISO 2858 constrains only the dimensional envelope of an end-suction process pump, so any conforming pump fits any conforming baseplate. ANSI B73.1 constrains the same dimensional envelope and adds mechanical design requirements covering shaft deflection, bearing life, and the seal chamber. The mechanical partner to ISO 2858 is ISO 5199; ANSI B73.1 bundles both roles into one document.

The water performance curve stops applying above roughly 20 to 40 cSt for typical process-pump sizes; heavy fuel oil, glycerin, and some crude oils cross that line. Head, flow, and efficiency then need correction per ANSI/HI 9.6.7, and absorbed power rises, so motor sizing has to be revisited. Above the correction range a positive-displacement pump usually becomes the better choice.

A duty point is where the chain starts, not where it ends. From flow and head, specific speed sorts the impeller into radial, mixed flow, or axial geometry. The standard the pump is built to, whether ISO 2858, ISO 5199, ANSI B73.1, or API 610, then sets what the casing and bearing frame are allowed to be. NPSH margin follows, held as a ratio against NPSHr rather than a fixed meter, because a published NPSHr is a 3 percent head-drop point and not the onset of cavitation. The preferred operating region around BEP decides how long the bearings and seals will last, since a rated point is only useful if the process stays near it. Above the 20 to 40 cSt band the water curve stops being the pump's curve, and the motor must be sized for the power viscosity adds. The seal plan is read off the liquid, and the datasheet the supplier receives carries every one of those decisions. Holding the same duty point, an engineer can now specify a centrifugal pump end to end and defend every field on the datasheet.

1. Hydraulic Institute. (2024a). ANSI/HI 9.6.1 rotodynamic pumps: Guideline for NPSH margin. Parsippany, NJ. https://www.pumps.org/product/ansi-hi-9-6-1-rotodynamic-pumps-guideline-for-npsh-margin
2. Hydraulic Institute. (2024b). ANSI/HI 9.6.3 rotodynamic pumps: Guideline for operating regions. Parsippany, NJ. https://www.pumps.org/product/ansi-hi-9-6-3-rotodynamic-pumps-guideline-for-operating-regions
3. Hydraulic Institute. (2021). ANSI/HI 9.6.7-2021 rotodynamic pumps: Guideline for effects of liquid viscosity on performance. Parsippany, NJ. https://www.pumps.org/product/ansi-hi-9-6-7-2021-rotodynamic-pumps-guideline-for-effects-of-liquid-viscosity-on-performance
4. Hydraulic Institute. (2022). ANSI/HI 14.6 rotodynamic pumps for hydraulic performance acceptance tests. Parsippany, NJ. https://www.pumps.org/product/ansi-hi-14-6-rotodynamic-pumps-for-hydraulic-performance-acceptance-tests
5. American Petroleum Institute. (2021). API standard 610: Centrifugal pumps for petroleum, petrochemical and natural gas industries (12th ed., dual-numbered ISO 13709). Washington, DC. https://www.api.org/products-and-services/standards/important-standards-announcements/standard-610
6. American Petroleum Institute. (2014). API standard 682: Pumps — Shaft sealing systems for centrifugal and rotary pumps (4th ed., dual-numbered ISO 21049). Washington, DC. https://www.api.org/products-and-services/standards/important-standards-announcements/standard-682
7. Karassik, I. J., Messina, J. P., Cooper, P., & Heald, C. C. (2008). Pump handbook (4th ed.). McGraw-Hill. https://openlibrary.org/works/OL2680056W
8. Turbomachinery Laboratory, Texas A&M University. (n.d.). Influence of impeller suction specific speed on vibration performance [Short course lecture 11]. https://turbolab.tamu.edu/wp-content/uploads/2018/08/Lecture_11.pdf
9. Grist, E. (2023). Net positive suction head (NPSH) and the pump operational range. In Cavitation and the centrifugal pump (pp. 51-69). Taylor & Francis. https://doi.org/10.1201/9781315138923-4
10. Sulzer Pumps. (2010). Behavior of centrifugal pumps in operation. In Centrifugal pump handbook (pp. 27-68). Butterworth-Heinemann. https://doi.org/10.1016/b978-0-7506-8612-9.00002-4
11. International Organization for Standardization. (1975). ISO 2858:1975 End-suction centrifugal pumps (rating 16 bar): Designation, nominal duty point and dimensions. Geneva, Switzerland. https://www.iso.org/standard/7862.html
12. International Organization for Standardization. (2002). ISO 5199:2002 Technical specifications for centrifugal pumps: Class II. Geneva, Switzerland. https://www.iso.org/standard/31945.html
13. American Society of Mechanical Engineers. (2012). ASME B73.1-2012 Specification for horizontal end suction centrifugal pumps for chemical process. New York, NY. https://www.asme.org/codes-standards/find-codes-standards/b73-1-specification-horizontal-end-suction-centrifugal-pumps-chemical-process
14. Hallam, J. L. (1982). Centrifugal pumps: Which suction specific speeds are acceptable? Hydrocarbon Processing, 61(4). https://www.osti.gov/biblio/7018728

Last reviewed and updated: September 2026. Author: Shinjo Pump engineering team. For pump selection support or a quotation on your duty point, contact our team.