Axially Split Double-Suction Pump · KSB Omega Pattern · Replacement Review
The S series is YSM’s single-stage, double-suction, axially split volute pump, built in compliance with GB/T 5657 (technical specifications for centrifugal pumps, Class III) and supplied as a non-OEM replacement and equivalent for KSB Omega-type installations in water works, HVAC circulation, power-station and industrial cooling water, irrigation, drainage and fire-fighting service. The programme covers DN 80 to DN 800 discharge, flows to 11,600 m³/h and heads to 200 m at 2900, 1450, 960 or 725 r/min, in horizontal or vertical arrangement. An Omega replacement is decided at the interfaces, not on the duty point alone: flange sizes and rating, nozzle centrelines, shaft height, coupling and baseplate bolt pattern are matched to the installed pump drawing before a size is quoted. This page records the reference envelope, the 52 size and speed combinations in the standard tables, the materials, and the data YSM reviews before quoting a complete pump, a bare-shaft pump, a rotating assembly or parts.
The Omega Pattern in the YSM Programme
The KSB Omega is an axially split, single-stage volute casing pump with a double-entry impeller carried between bearings. The S series delivers the same construction class: the casing is split along the shaft axis, the upper half (pump cover) lifts off for inspection or rotor removal while the suction and discharge piping stay connected, and the double-suction impeller balances axial thrust hydraulically so the bearings at both shaft ends carry radial load and residual thrust only. YSM builds the S series in compliance with GB/T 5657 and offers it where an Omega, an Omega V or another split case pump is due for replacement, duplication or a spare rotating assembly.
GB/T 5657 is a technical-specification standard, not a dimensional interchange standard, and the Omega is built to KSB’s own drawings, so YSM does not claim blanket interchangeability. For every enquiry the installed pump’s general-arrangement drawing, or its nameplate and site measurements, is compared with the S series size that covers the duty, and any difference in flange, centreline, shaft height or bolt pattern is reported before order. Where a direct match is not possible, a transition baseplate or spool piece is included in the quotation rather than left for site to discover.
What is matched
Installation and mechanical interfaces
- Suction and discharge flange sizes (DN1 / DN2), pressure rating and drilling
- Nozzle centreline heights and the spacing between suction and discharge
- Shaft centre height above the baseplate or foundation
- Foundation bolt pattern, baseplate outline, coupling type and spacing
- Rotation, nozzle orientation and the Rp 3/8 gauge, vent and drain connections
What is reviewed
Hydraulics, materials and driver
- Flow, head and speed against the size-specific curve and impeller trim, with NPSH available checked against NPSHr
- Liquid, temperature (to 105 °C) and cleanliness against casing, impeller, shaft and wear-ring materials
- Shaft seal: mechanical seal or gland packing, with rinse or flush piping where fitted
- Motor rating, frame and voltage (LV Y-type motors, or 6 kV motors on the larger sizes), coupling and baseplate
- Documentation: GA drawing, nameplate photo, sectional drawing or part references
Reference Envelope
| Parameter | S series | Note |
|---|---|---|
| Discharge size | DN 80 to DN 800 | 52 size and speed combinations, 102 impeller variants in the standard tables |
| Capacity | To 11,600 m³/h | Catalogue envelope; the highest-flow variant, 800-840(I) at 725 r/min, is tabled to 11,700 m³/h |
| Head | To 200 m | Catalogue envelope; the standard size tables reach 170 m (350-700 at 1450 r/min) |
| Speed | 2900 / 1450 / 960 / 725 r/min | 2900 r/min (G versions) DN 80 to 125; 1450 r/min DN 80 to 400; 960 r/min DN 500 to 700; 725 r/min DN 800 |
| Temperature | To 105 °C | Standard construction |
| Working pressure | To 25 bar | Hydrostatic test pressure 37.5 bar |
| Impeller | Double-suction, between bearings | Axial thrust balanced hydraulically; standard and (I) flow-expanded profiles, trimmed to duty |
| Casing | Axially split volute | Upper half removable with the piping in place |
| Shaft seal | Mechanical seal or gland packing | Mechanical seal rated for 8,000 h leak-free running |
| Arrangement | Horizontal or vertical | Vertical OA / OB frames with the motor above the pump; no adjustment at assembly |
These values are the catalogue envelope of the S series. Every quotation is confirmed on the size-specific curve at the actual speed and impeller trim, and the interface review above decides whether the size fits the existing foundation and pipework.
Size Coverage by Speed
Model designation follows the catalogue: S 150-360 (I) G A reads as discharge DN 150, 360 the nominal impeller-diameter code (the tabled trims for size 150-360 run 274 to 355 mm), (I) flow-expanded impeller, G 2900 r/min high-speed version, A first impeller cut. The table lists every base size in the standard programme with its flow and head envelope across the listed impeller diameters and the (I) variant, and the largest catalogue motor for that size.
| Size (DN-impeller) | Speed r/min | Capacity m³/h | Head m | Largest motor kW | Catalogue variants |
|---|---|---|---|---|---|
| 80-210 | 1450 | 47–100 | 6.5–15 | 5.5 | 80-210, 80-210(I) |
| 80-210 | 2900 | 91–197 | 27–60.5 | 37 | 80-210(G), 80-210(I)G |
| 80-270 | 1450 | 53–125 | 10.8–24 | 11 | 80-270, 80-270(I) |
| 80-270 | 2900 | 110–248 | 42–97.5 | 75 | 80-270(I)G, 80-270G |
| 80-370 | 1450 | 53–136 | 17.5–41 | 22 | 80-370, 80-370(I) |
| 100-250 | 1450 | 75–173 | 9.5–21.2 | 11 | 100-250, 100-250(I) |
| 100-250 | 2900 | 150–346 | 37–83 | 90 | 100-250(I)G, 100-250G |
| 100-310 | 1450 | 94–222 | 15–34 | 22 | 100-310, 100-310(I) |
| 100-310 | 2900 | 182–440 | 60–135 | 200 | 100-310(I)G, 100-310G |
| 100-375 | 1450 | 92–220 | 25–57 | 45 | 100-375, 100-375(I) |
| 125-230 | 1450 | 156–328 | 6.8–17 | 18.5 | 125-230, 125-230(I) |
| 125-230 | 2900 | 305–639 | 30–68 | 132 | 125-230(I)G, 125-230G |
| 125-290 | 1450 | 138–323 | 11.3–29.2 | 30 | 125-290, 125-290(I) |
| 125-290 | 2900 | 274–640 | 47–117 | 200 | 125-290(I)G, 125-290G |
| 125-365 | 1450 | 158–360 | 20.9–50 | 75 | 125-365, 125-365(I) |
| 125-500 | 1450 | 161–393 | 40–82 | 110 | 125-500, 125-500(I) |
| 150-290 | 1450 | 265–531 | 9.8–24 | 37 | 150-290, 150-290(I) |
| 150-360 | 1450 | 233–536 | 16.7–41.3 | 75 | 150-360, 150-360(I) |
| 150-460 | 1450 | 260–618 | 28.2–71 | 132 | 150-460, 150-460(I) |
| 150-605 | 1450 | 323–700 | 50–112 | 250 | 150-605, 150-605(I) |
| 200-320 | 1450 | 412–834 | 14.2–34 | 75 | 200-320, 200-320(I) |
| 200-420 | 1450 | 375–850 | 24–57 | 132 | 200-420, 200-420(I) |
| 200-520 | 1450 | 478–980 | 38–97 | 315 | 200-520, 200-520(I) |
| 200-670 | 1450 | 455–936 | 73–157.5 | 500 | 200-670, 200-670(I) |
| 250-370 | 1450 | 680–1,260 | 16–44 | 160 | 250-370, 250-370(I) |
| 250-480 | 1450 | 527–1,408 | 28.5–95.5 | 280 | 250-480, 250-480(I) |
| 250-600 | 1450 | 640–1,490 | 56.5–126 | 560 | 250-600, 250-600(I) |
| 300-300 | 1450 | 560–1,318 | 7.5–28.8 | 110 | 300-300, 300-300(I) |
| 300-435 | 1450 | 1,066–2,012 | 24–60 | 315 | 300-435, 300-435(I) |
| 300-560 | 1450 | 1,026–2,095 | 41–101.5 | 630 | 300-560, 300-560(I) |
| 350-360 | 1450 | 950–2,077 | 9–37.5 | 200 | 350-360, 350-360(I) |
| 350-430 | 1450 | 1,486–3,292 | 15–49.5 | 450 | 350-430, 350-430(I) |
| 350-510 | 1450 | 1,555–3,132 | 30–80 | 630 | 350-510, 350-510(I) |
| 350-620 | 1450 | 1,020–2,640 | 69–139 | 1,000 | 350-620(I) |
| 350-700 | 1450 | 1,074–2,082 | 71.5–170 | 1,120 | 350-700, 350-700(I) |
| 400-540 | 1450 | 1,110–3,420 | 33–98.5 | 900 | 400-540, 400-540(I) |
| 400-620 | 1450 | 1,265–4,100 | 49.8–129.5 | 1,400 | 400-620, 400-620(I) |
| 500-510 | 960 | 1,365–3,925 | 8–33 | 280 | 500-510, 500-510(I) |
| 500-640 | 960 | 1,530–4,500 | 18–52.5 | 500 | 500-640, 500-640(I) |
| 500-700 | 960 | 1,450–5,040 | 26.5–73 | 1,000 | 500-700, 500-700(I) |
| 500-790 | 960 | 1,710–5,150 | 36–88.5 | 1,250 | 500-790, 500-790(I) |
| 500-890 | 960 | 1,840–5,500 | 56–124 | 1,800 | 500-890, 500-890(I) |
| 600-540 | 960 | 1,890–6,080 | 8.5–33.7 | 400 | 600-540, 600-540(I) |
| 600-620 | 960 | 1,770–5,940 | 18–48 | 630 | 600-620, 600-620(I) |
| 600-710 | 960 | 1,740–6,050 | 27–69 | 900 | 600-710, 600-710(I) |
| 600-830 | 960 | 2,080–6,950 | 32–105 | 1,800 | 600-830, 600-830(I) |
| 700-590 | 960 | 2,610–8,060 | 10–38.8 | 710 | 700-590, 700-590(I) |
| 700-710 | 960 | 2,780–8,460 | 21–58.5 | 1,000 | 700-710, 700-710(I) |
| 700-820 | 960 | 2,340–9,600 | 35.5–92 | 2,000 | 700-820, 700-820(I) |
| 800-740 | 725 | 3,760–11,000 | 10.5–37.8 | 800 | 800-740, 800-740(I) |
| 800-840 | 725 | 3,630–11,700 | 16.8–56.4 | 1,400 | 800-840, 800-840(I) |
| 800-970 | 725 | 3,840–11,600 | 25–75.5 | 2,000 | 800-970 |
Ranges span the minimum and maximum catalogue points across all listed impeller diameters; a single trim covers a narrower band, and the (I) variant of a size runs at the same speed with a wider impeller. Duties outside the standard tables can be designed to order.
The full S series catalogue (PDF, 68 pages, 13.5 MB, Chinese / English) with every operating point, the performance charts, the sectional drawing and parts list, the materials table and the vertical-unit dimension tables can be downloaded here: YSM S Series Split Case Pump Catalogue. It is also listed under Technical Downloads.
Four Interfaces Checked Before a Pump Is Built
Flanges and nozzle centrelines
Suction and discharge DN, rating and drilling, and the centreline heights and spacing are compared with the installed pump so the existing pipework is reused without spool changes.
Baseplate and foundation
Foundation bolt pattern, baseplate outline and anchor positions are matched, or a transition baseplate is designed; vertical OA / OB frames are checked against the existing pedestal and secondary grouting.
Shaft height, coupling and driver
Shaft centre height, coupling type and spacing, direction of rotation and motor frame are confirmed when the driver is reused; a new motor is sized for the largest trim the duty may need.
Seal chamber and auxiliaries
Mechanical seal or packing, sleeve and gland dimensions, rinse and flush piping, and the Rp 3/8 gauge, vent and drain connections are listed against the existing pump so that site piping lands in the same places.
Horizontal or Vertical Arrangement
Horizontal
Pump on a baseplate with a flexible coupling to the motor, bearing housings at both shaft ends and the pump cover lifted straight off for rotor inspection while suction and discharge stay connected. This corresponds to the standard horizontal Omega; the Omega V is the vertical variant.
Vertical (OA / OB)
For pump houses with limited floor area the same hydraulic end is mounted vertically with a Y-type motor above the pump on an OA or OB frame. The catalogue dimension tables cover 28 vertical unit sizes from 80-210 to 350-510 (DN 80 to DN 350) with Y-type motors from 2.2 kW to 1,120 kW (6 kV YL motors on the larger frames), including flange sizes, pump and motor dimensions, and pump weight and water content; other sizes in vertical arrangement are reviewed on request.
Where the S Series Runs
Water works and municipal supply
Raw and treated water pumping at treatment plants, booster and transfer stations, where high flow at moderate head and long service intervals are the ruling criteria.
HVAC and district cooling circulation
Chilled and condenser water circulation for large buildings and district cooling loops, where the double-suction design keeps NPSHr low and the split casing keeps maintenance inside the pump room.
Power station and industrial cooling water
Circulating and service water for power plants and process industries, including the 6 kV motor sizes on the larger frames.
Irrigation, drainage, fire-fighting and marine
Irrigation and drainage pump stations, fire-fighting water supply and shipboard service are within the catalogue scope; fire service is quoted to the project specification.
Supply Scope
Complete pump
Bare-shaft pump, or pump with motor, coupling, guard and baseplate as a complete unit, horizontal or vertical, tested on the factory curve before dispatch.
Replacement for an installed Omega-type pump
S series size selected from the installed duty and interfaces, with matching dimensions, and any transition baseplate or spool piece, confirmed against the installed pump drawing before order and included in the quotation.
Replacement parts and assemblies
Impellers, shafts, shaft sleeves, casing wear rings, bearing housings, mechanical seals and packing sets, and complete rotating assemblies for S series pumps.
Reverse engineering
Worn or undocumented split case parts can be measured and re-drawn against the customer’s sample, with the material confirmed by spectrometer analysis before casting.
Materials, Seals and Bearings
| Part | Standard options (GB grade) |
|---|---|
| Pump casing and cover | Grey cast iron HT250; ductile iron QT400-18; cast steel ZG230-450 |
| Impeller | Tin bronze ZCuSn10Pb1; grey cast iron HT250; silicon brass ZCuZn16Si4; stainless steel ZG1Cr18Ni9Ti |
| Shaft | Stainless steel 2Cr13; carbon steel 45 |
| Casing wear rings | Tin bronze ZCuSn10Pb1; grey cast iron HT250; silicon brass ZCuZn16Si4; stainless steel ZG1Cr18Ni9Ti |
Seals and bearings
Mechanical seals from Burgmann or an equivalent domestic make, rated for 8,000 h of leak-free running, or gland packing with rinse piping. Rolling bearings from SKF, NSK or an equivalent domestic make in bearing housings at both shaft ends, for stable running, low noise and long life.
Beyond the catalogue list
316 stainless (CF8M) and duplex CD4MCu wetted parts from YSM’s process-pump foundry programme are quoted case by case for corrosive or brackish duties. Standard tests are spectrometer and chemical analysis of castings, hydrostatic test, impeller balancing and a performance-curve test; EN 10204 3.1 certificates on request; witness tests and SGS, BV or TÜV inspection accepted.
Material and seal selection is confirmed at quotation against the liquid, the temperature and the construction of the existing pump.
Data That Closes an Omega Enquiry in One Cycle
Identification: existing pump make, model and size from the nameplate, serial number if available. Duty: flow, head, speed and NPSH available. Process: liquid, concentration, temperature, solids. Interfaces: GA drawing or site measurements of flange sizes, nozzle centrelines, shaft height and bolt pattern. Seal: mechanical seal or packing, flush plan if any. Driver: reuse or new, motor power, voltage, frame, coupling and rotation. Arrangement: horizontal or vertical. Quantity, documentation needs, destination and target delivery date. Anything unknown can be marked as unknown.
KSB Omega Replacement FAQ
What does “KSB Omega equivalent” mean for the YSM S series?
It means the same construction class and duty coverage: a single-stage, double-suction, axially split volute pump that can take over an Omega duty in the same pump room. It does not mean every Omega size is a bolt-for-bolt match. YSM compares the installed pump’s flange sizes, centrelines, shaft height and bolt pattern with the S series size that covers the duty and reports every dimension that matches or needs an adapter before order.
Is the S series dimensionally interchangeable with an installed Omega?
Case by case. The S series is built to YSM’s own drawings in compliance with GB/T 5657 and the Omega to KSB’s own drawings, so flange-to-flange and baseplate dimensions cannot be assumed to match. Send the GA drawing or the site measurements listed above and the interchange review will state, dimension by dimension, what matches and what needs an adapter; where dimensions differ, a transition baseplate or spool piece is included in the quotation.
What sizes, flows and heads does the S series cover?
Discharge DN 80 to DN 800; 47 to 11,700 m³/h and 6.5 to 170 m on the standard size tables, within a catalogue envelope of 11,600 m³/h and 200 m. Speeds are 2900 r/min for DN 80 to 125 (G versions), 1450 r/min for DN 80 to 400, 960 r/min for DN 500 to 700 and 725 r/min for DN 800. Duties outside the tables can be designed to order.
Can the pump be installed vertically?
Yes. The vertical OA and OB frames carry a Y-type motor above the pump and are dimensioned in the catalogue for 28 sizes from 80-210 to 350-510 with motors from 2.2 kW to 1,120 kW; no adjustment is needed at assembly for either arrangement. Other sizes in vertical arrangement are reviewed on request.
Which shaft seals and bearings are fitted?
Mechanical seals from Burgmann or an equivalent domestic make, rated for 8,000 hours of leak-free running, or gland packing with rinse piping; rolling bearings from SKF, NSK or an equivalent domestic make. The seal type, sleeve and gland dimensions of the existing pump are checked so that flush and rinse piping land in the same places.
Can YSM supply only an impeller, wear rings or a rotating assembly for a split case pump?
Yes, once the part identity, mating dimensions, material and quantity are confirmed from a drawing, a sample or the nameplate. Impellers, shafts, sleeves, wear rings, bearing housings, seals and complete rotating assemblies are quoted individually; worn parts without drawings are measured and re-drawn.
What are the lead time and warranty for this pump?
Typical lead time is 4 weeks for a complete pump, 2 weeks for a bare wet end and 1 week for replacement parts, from deposit and approved drawings. Warranty is 12 months from shipment against defects in materials and workmanship within the reviewed duty. Late shipment attributable to YSM is compensated at 0.5% of contract value per week, capped at 5%.
What are the payment and delivery terms?
30% T/T deposit within 7 days of order, 70% T/T before shipment, or irrevocable L/C at sight; export-grade wooden-case packing; any Incoterms 2020 term (EXW Zibo, FOB Qingdao, CIF, DAP/DDP) as agreed in the quotation. Factory witness testing and third-party inspection (SGS, BV, TÜV) are accepted. Full terms: Commercial Terms
KSB and Omega are trademarks or product identifiers of KSB SE & Co. KGaA and are used solely for identification and replacement-reference purposes. YSM Pumps (Jinan Yingsiman Machinery Co., Ltd.) is an independent, non-OEM manufacturer and is not affiliated with, sponsored by or endorsed by KSB.
Request an Omega Replacement Quote
A complete enquiry closes in one review cycle. Include the installed pump make, model and size, a nameplate photo, the GA drawing or site measurements of flange sizes, nozzle centrelines, shaft height and bolt pattern, the duty (flow, head, speed, NPSH available), the liquid (composition, concentration, temperature, solids), the seal type, driver data if the motor is reused, horizontal or vertical arrangement, quantity, documentation needs, destination and target delivery date.
Anything unknown can be stated as unknown — a marked gap is reviewable, a silent one is not.
Split Case Selection Decision Guide
Selection boundaries save both sides a review cycle: the fastest quotation starts on the right page. The S series is the high-flow, clean-liquid answer inside YSM’s programme — crossing to another page is not a downgrade, it is a different answer to a different installation.
Start with the S series when
- The liquid is clean or lightly contaminated water or a similar low-viscosity liquid up to 105 °C, and the flow is beyond what an end-suction pump covers efficiently, from roughly 50 to 11,600 m³/h.
- An installed KSB Omega, Omega V or other double-suction split case pump needs a complete replacement, a bare-shaft pump, a rotating assembly or wear parts.
- Maintenance access without disturbing pipework matters, or the pump room needs a vertical unit with the motor above the pump.
Review another page when
- The duty is chemical process service to ANSI/ASME B73.1 or ISO 5199: see the G196 or AC pages.
- The liquid carries solids, fibre or pulp: see the DN non-clogging or paper stock pump pages.
- The head is above 200 m or the service is refinery duty to API 610: see the KM multistage or KZ OH2 pages; for a pit or deep-well installation see the G171 or KVT pages.