Three manufacturers and the pump families worth comparing
This shortlist concerns horizontal end-suction centrifugal pumps for compatible clean industrial water. It excludes slurry, solids-handling and metering duties. The three manufacturer groups appear alphabetically, without a quality or efficiency ranking. Original product documents and current site information were checked October 19, 2026; individual document dates are retained below.
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| Manufacturer group | Family to request | Assembly distinction | Published hydraulic source |
|---|---|---|---|
| Grundfos | NK; NB is the close-coupled alternative. | Long-coupled NK can use standard or spacer coupling; specify the offered build. | NB/NK 80-315, 4-pole 60 Hz chart; document 98188596, p. 100. |
| KSB | Etanorm | Back pull-out construction; a spacer coupling changes the motor-removal procedure. | Etanorm 100-080-315, 1750 rpm; 1311.46/12-EN-US, p. 79. |
| Xylem Goulds Water Technology | 3756 M-Group; 3656 is the close-coupled alternative. | 3756 is bearing-frame mounted; bedplate, guard and spacer coupling are listed options. | Model 14AI/BF, 3 × 4–13, 1750 rpm; B3656M-L R8, p. 14. |
Grundfos NK, KSB Etanorm and Goulds 3756M: pumps and curves
Grundfos NK: use the actual 60 Hz chart
Grundfos’ NK/NKG instructions, document 96658410, April 2021, §2.1.1, limit this inquiry to clean, thin, non-explosive liquids without solids or fibers and without chemical attack on the pump materials. Its November 2025 NK/NKE booklet lists industrial liquid transfer and waterworks applications.
The separate German-language NB, NBE, NK, NKE 60 Hz booklet, document 98188596, December 2019, p. 100, shows NB/NK 80-315 at 4-pole 60 Hz. The example’s normal duty falls between displayed impeller curves. This is an identifiable NK inquiry lead, using a dated published chart; the current manufacturer selection must confirm the actual speed, trim and accepted operating range.
KSB Etanorm: keep trim, materials and seal choices separate
KSB’s Etanorm type-series booklet 1311.52/01-EN-US describes a horizontal, single-stage water-pump family with back pull-out construction. It identifies casing and impeller materials separately and provides multiple seal arrangements. “Etanorm” alone therefore does not specify the wetted materials, seal or connections of the proposed unit.
Its 60 Hz curves, 1311.46/12-EN-US, April 2025, p. 79, include Etanorm 100-080-315 at 1750 rpm. The 500 US gpm, 120 ft point lies between the displayed 265 mm and 290 mm impeller curves. Ask KSB to establish the actual trim and performance; do not turn that visual bracket into an already selected impeller diameter.
Xylem Goulds 3756M: name the bearing-frame assembly
Xylem’s March 2026 B3656M-L R8 distinguishes the close-coupled 3656 from the bearing-frame-mounted 3756. Page 14 provides the 1750 rpm Model 14AI/BF, 3 × 4–13 curves, CN0112R00 and CN0118R00. The normal inquiry point lies within the displayed trim range. For the maintenance preference in the example, request the 3756M assembly, not an unspecified “3656/3756” offer.
The same brochure lists all-iron and bronze-fitted constructions and optional bedplate, coupling guard and spacer coupling. Those are choices in the supplied package. The Xylem IM010R011 manual separates close-coupled and frame-mounted maintenance and identifies the repair parts; it does not establish local parts inventory or a repair turnaround commitment.
Spacer couplings and pump-service clearance
All three candidates offer back pull-out construction. To leave the motor and connected casing in place during service, specify the coupling and removal arrangement in the actual proposal.
Specify the coupling that delivers the intended access
Grundfos’ 60 Hz booklet, p. 40, distinguishes standard and spacer couplings; the spacer arrangement permits service while retaining the motor on the base frame and the pump housing in the pipework. KSB’s July 2026 Etanorm manual, §7.4.3, likewise permits the motor to remain bolted down with a spacer-type coupling. Its §7.4.4 non-spacer procedure calls for motor removal. Xylem lists a spacer coupling as an option for 3756 and gives the corresponding frame-mounted disassembly scope in IM010R011, p. 9.
If technically acceptable assemblies with and without a spacer are both offered, prefer the documented spacer arrangement for that maintenance objective. If a compact close-coupled unit better serves the site and motor removal is acceptable, reconsider Grundfos NB or Goulds 3656 instead. The actual removal space, assembly drawing and service procedure decide whether either arrangement fits.
Check the support actually offered with the assembly
Obtain the parts list for the quoted build, the proposed spare seal and wear parts, and the party responsible for commissioning and repair. Confirm parts availability and response time against the owner’s outage window.
One transfer brief, three named manufacturer inquiries
Give every manufacturer the same two operating conditions
Hypothetical project brief. A plant requires one electric pump assembly for clean, non-potable treated water at 68°F (20°C). The normal condition is 500 US gpm at 120 ft total head. A second required condition is 400 US gpm at 100 ft under the proposed speed-control strategy. Supply is three-phase, 460 V, 60 Hz. The project has defined suction conditions, pressure limits, water chemistry, accepted materials and installation constraints; each proposal must be checked against them.
The owner wants a long-coupled or bearing-frame assembly with a spacer coupling so the motor can remain installed during pump service. The normal duty converts to 113.56 m³/h at 36.58 m for metric chart axes. The manufacturer must select the actual impeller and speed-control arrangement for both conditions; a speed ratio alone does not establish the second point.
Send these three specific starting inquiries
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| Manufacturer inquiry | Actual chart lead | Assembly to request | Still required from the proposal |
|---|---|---|---|
| Grundfos NK 80-315 | 4-pole 60 Hz chart, p. 100: normal point between the displayed 275 mm and 287 mm curves. | NK with the proposed spacer coupling, motor and base frame. | Current application-specific curve, actual speed and trim; second-condition performance and accepted assembly. |
| KSB Etanorm 100-080-315 | 1750 rpm chart, p. 79: normal point between the displayed 265 mm and 290 mm curves. | Etanorm with spacer coupling, specified material/seal build, motor and baseplate. | Actual trim and both duty conditions; offered flange variant and service-removal drawing. |
| Xylem Goulds 3756M, Model 14AI/BF, 3 × 4–13 | 1750 rpm curves, p. 14: normal point within the displayed impeller-trim range. | 3756M bearing-frame assembly with spacer coupling, motor, bedplate and guard. | Exact material/model code, impeller and both duty conditions; confirmation of the complete supplied package. |
Send all three manufacturers the same two-duty inquiry and spacer-coupling requirement. A proposed Grundfos NB, Goulds 3656 or non-spacer package changes the maintenance arrangement and should be assessed as an alternative.
Compare selections that cover both conditions with suitable suction margin, operating range, power and pressure limits. Check the service-removal drawing and match the included motor, drive, base, coupling, guard, seal and initial spares.
If the owner accepts motor removal and prioritizes a different installation arrangement, reopen the configuration choice before requesting revised offers. If the fluid becomes solids-laden or materially more corrosive, these clean-water family leads need a new assessment. For the earlier decision between pump configurations and annual operating profiles, use the industrial water-transfer pump selection guide.
Frequently asked questions
Are Goulds Water Technology and ITT Goulds Pumps the same manufacturer?
No. The 3656/3756 documents used here are issued by Xylem for Goulds Water Technology. ITT identifies Goulds Pumps as its own pump business. State the group, family and complete model on the inquiry; shared use of the Goulds name does not make their curves, parts or support arrangements interchangeable.
Can a 50 Hz NK data sheet support the 60 Hz offer?
It cannot establish the offered hydraulic performance. The November 2025 NK/NKE booklet reviewed here is labeled 50 Hz CHINA. Use a curve for the offered 60 Hz construction and actual speed. The separate 60 Hz chart cited in the example is a dated inquiry lead; require the current selection with the proposal.
What identifies the replacement mechanical seal for a Goulds 3756M?
Provide the complete pump product code and serial number, then match the installed seal arrangement, faces and elastomers. B3656M-L R8, p. 4, lists seal codes, material combinations and different part-number columns; IM010R011, pp. 2 and 12, records unit identity and repair components. Confirm the replacement for that build with the manufacturer. Horsepower or the 3756M family name alone is insufficient.
Does a factory-assembled 3756M package still need alignment checks on site?
Yes. IM010R011, p. 7, requires frame-mounted-unit alignment to be checked before running, with hold-down bolts tightened, and both alignments rechecked after mechanical adjustments. Page 8 notes that operating temperature differences can change coupling alignment. Include installation and final alignment in the agreed commissioning scope; a factory-assembled package does not close the site work.
Does an EN 733 pump designation settle the flange connection?
No. KSB’s Etanorm type-series booklet lists EN 1092 flanges and separate drilling to ASME B16.1 Class 125 or ASME B16.5 Class 150, with material-specific details. The family designation does not select the offered flange variant. Put the required nozzle and mating-flange details on the accepted assembly drawing.
Is the brochure curve the acceptance basis for the pump I order?
It is a starting reference, not an acceptance record for the supplied unit. Define the selected model and impeller, liquid, actual speeds, both required conditions, guaranteed quantities and agreed test and acceptance scope in the order. Obtain the corresponding manufacturer selection and any ordered test records. A family chart does not show that the delivered pump was tested at both project conditions, and it does not establish one acceptance grade for every offer.
Technical Basis and Source Scope
Grundfos: NK/NKG Installation and Operating Instructions, 96658410, April 2021, §2.1.1. NK/NKE data booklet, 92700011, November 2025, 50 Hz CHINA, p. 4 for applications only. NB, NBE, NK, NKE, EN 733, 60 Hz data booklet (German), 98188596, December 2019: p. 40, coupling; p. 71, curve conditions; p. 100, lower NB/NK 80-315 chart, TM03 5227 3414. The dated chart supplies an inquiry lead, not a current accepted selection.
KSB: Etanorm Type Series Booklet, 1311.52/01-EN-US, January 14, 2025: p. 4, family scope; pp. 5–6, build identification; pp. 38–41, flange variants. Etanorm Performance Curves, 60 Hz, 1311.46/12-EN-US, April 7, 2025: p. 4, conditions; p. 79, 100-080-315 at 1750 rpm. Etanorm Installation/Operating Manual, 1311.82/03-EN-US, July 2, 2026: p. 67, §§7.4.3–7.4.4, spacer and non-spacer removal arrangements.
Xylem Goulds Water Technology: 3656/3756 M- and L-Group Technical Brochure, B3656M-L R8, March 2026: p. 2, constructions and options; p. 4, model/seal codes and trim increments; p. 14, Model 14AI/BF, 3 × 4–13, 1750 rpm, CN0112R00/CN0118R00. IM010R011, May 2022: p. 2, unit identity; pp. 7–8, alignment before running and after adjustments or temperature changes; p. 9, disassembly; pp. 12–13, repair parts. ITT’s February 5, 2024 official release, “ITT to Provide Highly Engineered Pump Systems and Aftermarket Services,” opening paragraphs, identifies its separate Goulds Pumps business.
