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 genuine Interpump replacement piston (plunger) measuring 18 mm diameter by 25 mm, used to restore pressure and flow in W-series and compatible high-pressure plunger pumps. Buyers source it to rebuild pumps running at up to 200 bar (2,900 psi) rather than replace the whole unit.
What is the 51.0401.09 InterpumpGroup W1210 Piston D. 18x25?
A 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is a precision-ground plunger that reciprocates inside a pump's ceramic or stainless liner, displacing fluid on each stroke to generate high pressure. The "D. 18x25" designation specifies an 18 mm diameter and 25 mm length, which must match the pump's manifold bore and stroke.
Interpump Group is one of the world's largest manufacturers of high-pressure plunger pumps, and its W-series pistons are widely used in pressure washers, industrial cleaning skids, reverse-osmosis feed systems and agricultural sprayers. Because the piston is a wear part, correct identification is the single most important step before purchase.
According to Interpump Group technical documentation (SS3C2015, dated 3/21/2026): "Male shaft (key) - (plugs) - OUT OF PRODUCTION." This illustrates why buyers must verify current part availability and supersession before ordering legacy pump components.
How does an Interpump plunger piston work?
The piston is driven by a crankshaft and connecting rod, converting rotary motor power into a linear reciprocating stroke. On the suction stroke, an inlet valve opens and fluid fills the chamber; on the discharge stroke, the piston forces fluid through an outlet valve at high pressure.
Sealing is achieved by a combination of the piston surface finish and high-pressure seals (packings). When the piston wears, scores or corrodes, pressure drops, flow becomes erratic and seals fail prematurely — which is why replacing the piston and seals together is standard practice.
Key specifications at a glance
The table below summarises the typical operating envelope for pumps using an 18x25 piston of this class. Values reflect the representative Interpump pump data supplied in our catalog; always confirm against your specific pump nameplate.
| Parameter | Value | Notes |
|---|---|---|
| Piston diameter | 18 mm | Must match manifold bore |
| Piston length | 25 mm | Stroke-dependent |
| Operating pressure | 200 bar (2,900 psi) | Representative pump rating |
| Pressure (MPa) | 20 MPa | Metric equivalent |
| Flow rate | 15 L/min (3.96 US gpm) | Representative pump output |
| Rotation regime | 1,750 rpm | 50 Hz nominal |
| Power | 5.73 kW (7.8 hp) | Representative drive rating |
| Weight (pump assembly) | 9.5 kg | Reference only |
Which Interpump pump families use this piston class?
Interpump's W-series and related high-pressure plunger pumps share piston architecture across several output ratings. The table below compares representative Interpump pumps and spares available through 3G Electric, arranged from compact/light-duty to high-output industrial duty.
| Model | Flow | Pressure | Power | Typical duty |
|---|---|---|---|---|
| Inter[[PRODUCT:TS1331-000|pump TS1331 | 13 L/min | 120 bar | 2.94 kW | Light-duty cleaning |
| Inter[[PRODUCT:T01321-000|pump T1321 | Catalog-listed | Catalog-listed | Catalog-listed | General industrial |
| Inter[[PRODUCT:T09281S0U-000|pump T9281 L | Catalog-listed | Catalog-listed | Catalog-listed | Process / cleaning |
| Interpump T2830Y SX Pump with Motor | 30 L/min (7.92 US gpm) | 275 bar | 15.44 kW (21 hp) | Heavy-duty industrial |
| Interpump AB150 PTO Pump | Catalog-listed | Catalog-listed | Catalog-listed | Mobile / PTO drive |
Step up the ladder when your duty cycle moves from intermittent cleaning to continuous process work: the T2830Y SX delivers 30 L/min at 275 bar and 15.44 kW, roughly double the flow of a compact TS1331. Step down when portability or intermittent use matters more than peak pressure.
Selection criteria: how to choose the right piston and spares
- Confirm the pump series and serial number. Piston dimensions are family-specific; an 18x25 piston will not fit a manifold bored for a different diameter.
- Match diameter and length exactly. Verify 18 mm diameter and 25 mm length against the pump parts list, not a generic photo.
- Check pressure and flow rating. Ensure the replacement piston suits the pump's rated pressure (e.g. 200 bar / 2,900 psi) and flow (e.g. 15 L/min / 3.96 US gpm).
- Replace seals and valves at the same time. Worn packings accelerate new-piston wear; kits such as Interpump FOAMKIT 3 for T/TX Series and Interpump VarioJet Kit with 125 Nozzle support complete rebuilds.
- Verify drive coupling. A Interpump Flexible Coupling 56C ensures correct alignment between motor and pump, protecting the new piston from side-loading.
- Consider duty cycle and environment. Continuous industrial duty, abrasive fluids or high ambient temperatures demand more frequent inspection.
- Confirm voltage/frequency context. Pumps rated at 1,750 rpm suit 50 Hz supplies; 60 Hz regions typically run at 1,450–2,800 rpm, so confirm motor and pump pairing.
Applications in the Worldwide market
Interpump high-pressure pumps and their 18x25-class pistons serve industrial cleaning contractors, food and beverage washdown, reverse-osmosis and membrane filtration, agricultural spraying, and vehicle wash systems. In export markets, buyers frequently request spare pistons alongside complete pumps to minimise downtime between shipments.
Because piston wear is predictable, many worldwide operators stock a rebuild set — piston, seals, valves and coupling — rather than a complete spare pump. This reduces freight weight and customs complexity while keeping critical assets running.
Why source from 3G Electric
3G Electric stocks 4,007 products across 14 industrial departments — from pumps and controls to instrumentation, pneumatics and power transmission — and supplies far more than is listed online. With 35+ years of experience and specialist depth in combustion, pumps and controls, we interpret your requirement, confirm the correct part and quote it accurately.
We ship worldwide with export documentation experience and incoterms-neutral supply, so international buyers receive consistent pricing in USD regardless of destination. Our technical team can cross-reference your pump serial to the correct piston and seal set before you order.
Frequently asked questions
How do I confirm the 51.0401.09 piston fits my Interpump pump?
Match the pump's series and serial number against the parts list, then verify the piston's 18 mm diameter and 25 mm length. Because dimensions are family-specific, send us your pump nameplate details and we will cross-reference before quoting.
What pressure and flow does an 18x25 piston support?
Representative Interpump pumps in this class run at 200 bar (2,900 psi / 20 MPa) and 15 L/min (3.96 US gpm) at 1,750 rpm, drawing about 5.73 kW (7.8 hp). Actual figures depend on the specific pump model and drive configuration.
Where can I buy Interpump W1210 pistons in Worldwide?
3G Electric supplies Interpump pumps and spares worldwide with USD pricing and export documentation. Contact us with your pump model and we will confirm availability, lead time and shipping terms for your region.
Should I replace seals when fitting a new piston?
Yes. Worn high-pressure packings score new pistons and cause premature failure. Replacing piston, seals and valves together — and checking the flexible coupling — restores full pressure and extends service life.
Does 50 Hz vs 60 Hz affect piston selection?
Frequency affects pump speed: 50 Hz supplies typically run at 1,750 rpm, while 60 Hz regions run higher. The piston itself is dimension-driven, but confirm the motor-pump pairing and coupling to avoid over-speeding the pump.
What is the typical lead time for worldwide delivery?
Lead time depends on stock status and destination. In-stock spares usually ship quickly; special-order pistons may require additional time. 3G Electric confirms lead time and shipping terms at quotation.
Key takeaways
- The 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is an 18 mm x 25 mm replacement plunger for Interpump high-pressure pumps.
- Representative operating envelope: 200 bar (2,900 psi), 15 L/min (3.96 US gpm), 1,750 rpm, 5.73 kW (7.8 hp).
- Always verify pump series and serial before ordering — piston dimensions are not interchangeable.
- Replace seals, valves and coupling at the same time for a reliable rebuild.
- 3G Electric supplies Interpump pumps and spares worldwide with USD pricing and export documentation.
Ready to order or need sizing help? Contact 3G Electric for a quote on the 51.0401.09 InterpumpGroup W1210 piston D. 18x25, compatible Interpump pumps and rebuild kits. Our technical team supports worldwide buyers with cross-referencing, lead times and export documentation.
