51.0401.09 InterpumpGroup W1210 Piston D. 18x25: Complete Buyer's Guide for Worldwide Sourcing
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The 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is a factory-specification reciprocating piston (plunger) assembly for Interpump W-series high-pressure pumps, sized 18 mm diameter x 25 mm stroke-related length. It restores pressure and flow on pumps running around 200 bar (20 MPa / 2900 psi) at 15 L/min (3.96 US gpm) and 1750 rpm, and is ordered by matching your pump model, serial and piston diameter.
What is the 51.0401.09 InterpumpGroup W1210 piston D. 18x25?
A reciprocating pump piston is the moving element that displaces fluid inside a high-pressure pump cylinder, converting rotary drive from the crankshaft into pressure and flow. In Interpump W-series pumps, the piston/plunger is a hardened, ground and lapped component that runs against a seal pack and valve assembly.
The 51.0401.09 designation is InterpumpGroup's internal part reference; "W1210" identifies the pump family, and "D. 18x25" specifies an 18 mm diameter with a 25 mm nominal length dimension. Interpump is one of the most widely specified brands in industrial high-pressure cleaning, reverse-osmosis and process pumping, so genuine spares matter for seal life and pressure stability.
According to Interpump Group S.P.A. technical documentation (SS3C2015, dated 3/21/2026): "Male shaft (key) - (plugs) - OUT OF PRODUCTION" — a reminder that Interpump periodically supersedes pump configurations, so always confirm the current part number against your pump's serial plate before ordering.
How does a W-series piston work inside an Interpump pump?
The piston reciprocates inside a ceramic- or steel-lined cylinder, drawing fluid through an inlet valve on the suction stroke and forcing it through a discharge valve on the pressure stroke. Three pistons on a common crankshaft (a triplex configuration) smooth the flow pulsation and deliver the rated pressure.
Wear is concentrated on the piston surface, the low-pressure and high-pressure seals, and the valves. When pressure drops, flow falls off, or the pump runs hot, the piston and seal kit are usually the first items to inspect. Replacing the piston without renewing seals typically shortens the new part's life.
Spec table: 51.0401.09 W1210 piston D. 18x25
| Parameter | Value | Notes |
|---|---|---|
| Part reference | 51.0401.09 | InterpumpGroup internal spare-part number |
| Pump family | W1210 | Interpump W-series high-pressure pump |
| Piston diameter | 18 mm | "D. 18" in the part description |
| Nominal length dimension | 25 mm | "x25" in the part description |
| Typical rated pressure | 200 bar (20 MPa / 2900 psi) | Family-level rating; confirm per pump model |
| Typical rated flow | 15 L/min (3.96 US gpm) | At rated speed |
| Typical rotation regime | 1750 rpm | 50 Hz and 60 Hz drive variants exist |
| Typical drive power | 5.73 kW (7.8 hp) | Family-level reference |
| Typical pump weight | 9.5 kg | Complete pump, not the piston alone |
| Typical pump envelope | 273.5 x 223 x 152.5 mm | L x W x H, complete pump |
Values above are family-level reference figures drawn from Interpump technical documentation. Always verify against the serial plate of your specific pump before ordering a piston.
Which Interpump pumps and spares pair with this piston?
W-series pistons are commonly serviced alongside other Interpump pump families and accessories stocked by 3G Electric. If you are rebuilding a pump or upgrading a system, these are the most frequently co-ordered items:
- Inter[[PRODUCT:T01321-000|pump T1321 — compact triplex pump for cleaning and process duty.
- Inter[[PRODUCT:TS1331-000|pump TS1331 — 13 L/min at 120 bar, 2.94 kW, 1450 rpm.
- Inter[[PRODUCT:T09281S0U-000|pump T9281 L — larger frame for higher-flow duties.
- Interpump T2830Y SX Pump with 53R Motor — 30 L/min at 275 bar, 15.44 kW, 1750 rpm, 18.5 kg.
- Inter[[PRODUCT:AB0150CD-000|pump AB150 PTO R — PTO-driven variant for mobile and agricultural use.
- Interpump 56C Flexible Coupling — motor-to-pump coupling for correct alignment.
- Interpump VarioJet Kit with 125 Nozzle — downstream accessory for cleaning systems.
- Interpump FoamKit 3 for T/TX Series — foam injection accessory for T/TX pumps.
Selection criteria: how to choose the right piston
- Match the pump model and serial. Confirm "W1210" on the pump nameplate; Interpump supersedes configurations, so the serial is the authoritative reference.
- Confirm piston diameter. The 18 mm diameter must match the cylinder bore and seal kit; a mismatched diameter will leak or seize.
- Check rated pressure and flow. Family ratings around 200 bar (20 MPa / 2900 psi) and 15 L/min (3.96 US gpm) at 1750 rpm are typical — verify against your duty point.
- Renew seals and valves together. Piston, seal kit and valve kit are a wear set; replacing one alone usually shortens service life.
- Match drive frequency. Confirm whether your motor is 50 Hz or 60 Hz; the same pump can run at different rpm and therefore different flow.
- Verify fluid compatibility. Water, detergents, RO permeate and light process fluids behave differently against seals and piston materials.
- Plan the duty cycle. Continuous industrial duty justifies genuine Interpump spares; intermittent light duty may tolerate a shorter service interval.
Product selection ladder: Interpump pumps and spares
| Step | Model | Flow | Pressure | Power | Weight | Typical use |
|---|---|---|---|---|---|---|
| Entry / compact | Inter[[PRODUCT:TS1331-000|pump TS1331 | 13 L/min | 120 bar (12 MPa / 1740 psi) | 2.94 kW (3.9 hp) | — | Light cleaning, small RO skids |
| Mid-range | Inter[[PRODUCT:T01321-000|pump T1321 | — | — | — | — | General industrial cleaning |
| Mid-range, higher flow | Inter[[PRODUCT:T09281S0U-000|pump T9281 L | — | — | — | — | Process and washdown |
| Mobile / PTO | Inter[[PRODUCT:AB0150CD-000|pump AB150 PTO R | — | — | — | — | Agricultural and vehicle-mounted |
| Heavy duty | Interpump T2830Y SX Pump with 53R Motor | 30 L/min (7.92 US gpm) | 275 bar (27.5 MPa / 4000 psi) | 15.44 kW (21 hp) | 18.5 kg | Continuous high-pressure industrial duty |
Step up the ladder when your duty cycle moves from intermittent cleaning to continuous process work, or when you need higher flow at the same pressure. Step up to the T2830Y SX when 275 bar (27.5 MPa / 4000 psi) and 30 L/min (7.92 US gpm) are required; stay with the TS1331 or T1321 for lighter, intermittent duty where a smaller frame and lower power draw are advantages.
Why source the 51.0401.09 piston from 3G Electric?
3G Electric stocks 4,007 products across 14 industrial departments — machining, electrical, power transmission, material handling, plumbing, HVAC & refrigeration, pneumatics, hydraulics, pumps, instrumentation, test & measurement, welding, lighting and combustion/burner systems — with deep specialist depth in combustion, pumps and controls. That breadth means a single enquiry can cover the piston, the seal kit, the coupling and the drive motor.
With 35+ years of experience, we interpret the demand behind a part number rather than simply matching a string. We supply worldwide with export documentation experience, incoterms-neutral terms and cross-market voltage/frequency variants (50 Hz and 60 Hz) for pump and motor packages. We are a distributor and supplier — not an authorised dealer — and we are accountable for getting the right answer, not for claiming infinite warehouse stock.
Frequently asked questions
How do I identify the correct Interpump piston for my pump?
Read the pump nameplate for the model (e.g. W1210) and serial number, then confirm the piston diameter (18 mm) and length dimension (25 mm) against Interpump documentation. The serial is authoritative because Interpump supersedes configurations over time.
What pressure and flow does the W1210 family typically run?
Family-level reference figures are around 200 bar (20 MPa / 2900 psi) at 15 L/min (3.96 US gpm) and 1750 rpm, with roughly 5.73 kW (7.8 hp) drive power. Always verify against your specific pump's serial plate and duty point.
Can I buy the 51.0401.09 piston in Worldwide with export documentation?
Yes. 3G Electric supplies worldwide with export documentation experience and incoterms-neutral terms. Lead time depends on stock position and destination; request a quote with your pump serial and destination country for an accurate delivery estimate.
Should I replace seals and valves at the same time as the piston?
Yes. Piston, seal kit and valve kit form a wear set. Replacing the piston alone typically shortens its service life and can cause pressure loss or overheating shortly after the repair.
Does 50 Hz vs 60 Hz matter for this pump family?
Yes. The same pump can run at different rpm on 50 Hz and 60 Hz supplies, which changes flow. Confirm your motor frequency and target rpm (typically 1750 rpm) before ordering a piston or a complete pump package.
Is the 51.0401.09 piston compatible with other Interpump pump families?
No — piston diameter, length and seal interface are family-specific. The 18x25 piston is matched to the W1210 family. Cross-fitting to another family risks leakage, seizure or premature failure.
Key takeaways
- The 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is an 18 mm x 25 mm reciprocating piston for Interpump W-series high-pressure pumps.
- Family reference duty is around 200 bar (20 MPa / 2900 psi) at 15 L/min (3.96 US gpm) and 1750 rpm.
- Always order by pump model and serial, not by part number alone — Interpump supersedes configurations.
- Replace piston, seals and valves as a set to protect service life.
- 3G Electric supplies worldwide with export documentation, 50 Hz and 60 Hz variants, and technical support across 4,007 stocked products.
Next step
Contact 3G Electric for a quote on the 51.0401.09 InterpumpGroup W1210 piston D. 18x25, sizing assistance, or a full pump rebuild kit. Send your pump model, serial number and destination country, and our technical team will confirm the correct part, lead time and export documentation for worldwide delivery.
