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 plunger sized 18 mm diameter x 25 mm, used to restore pressure and flow in compatible Interpump high-pressure pump models. Buyers should match it to their pump's rated flow, pressure, and rotation regime before ordering.
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 assembly used inside Interpump positive-displacement high-pressure pumps to displace fluid on each stroke. It is a wear part: over time, plungers and seals degrade, causing pressure loss, pulsation, or leaks.
Interpump is one of the most widely specified OEMs in industrial pressure-washing, reverse-osmosis, and process pumping. Genuine Interpump spares such as the W1210 piston preserve the pump's original pressure curve and warranty position.
Quotable definition
A 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is an 18 mm diameter x 25 mm plunger spare part for Interpump high-pressure pumps, restoring the displacement and pressure performance of compatible pump models rated up to 200 bar (2900 psi) at 1750 rpm.
How does an Interpump plunger piston work?
Inside an Interpump pump, a crankshaft drives connecting rods that reciprocate each ceramic or hardened-steel plunger inside a sealed cylinder. On the suction stroke, inlet valves open and fluid enters; on the discharge stroke, outlet valves open and pressurised fluid exits.
The piston's diameter directly sets displacement per stroke. An 18 mm piston at 1750 rpm produces the flow and pressure envelope the pump was designed for — fitting a different diameter changes both flow (L/min) and pressure (bar).
Spec table: 51.0401.09 W1210 piston D. 18x25
| Attribute | Value |
|---|---|
| Part number | 51.0401.09 |
| OEM | Interpump Group |
| Component type | Piston / plunger spare |
| Piston diameter | 18 mm |
| Piston length | 25 mm |
| Compatible pump flow | 15 L/min (3.96 US gpm) |
| Compatible pump pressure | 200 bar (20 MPa / 2900 psi) |
| Rotation regime | 1750 rpm |
| Compatible pump power | 5.73 kW (7.8 hp) |
| Typical pump weight | 9.5 kg |
| Typical pump dimensions | 273.5 x 223 x 152.5 mm |
Values above reflect the Interpump pump envelope this piston family serves. Always confirm against your pump's nameplate before ordering.
Which Interpump pump families use this piston?
The 18 x 25 mm piston format is common across Interpump's mid-range triplex plunger pumps — the same class as the T-series and TS-series units widely used in pressure washing, misting, and industrial cleaning.
Representative Interpump pumps in the 3G Electric catalog include the Inter[[PRODUCT:TS1331-000|pump TS1331 (13 L/min at 120 bar, 2.94 kW, 1450 rpm) and the Inter[[PRODUCT:T01321-000|pump T1321. Larger frames such as the Interpump T2830Y SX Pump with 53R Motor (30 L/min at 275 bar, 15.44 kW) use different piston diameters and should not be assumed compatible.
Types and applications in Worldwide markets
- Pressure washing and cleaning — car washes, food plants, and industrial floors across North America, Europe, and Asia-Pacific.
- Reverse osmosis and misting — 50 Hz and 60 Hz installations where flow must stay stable.
- Agriculture and livestock — sprayer and washdown duty, often paired with PTO-driven pumps such as the Interpump AB150 PTO Pump.
- Process and OEM skids — pump rebuilds where genuine Interpump spares are required.
Selection criteria: how to choose the right piston
- Confirm the pump model and serial. Match the piston to the exact Interpump pump frame — do not assume cross-family fitment.
- Verify piston diameter. The 18 mm bore is fixed; a different diameter changes flow and pressure.
- Check rated pressure and flow. This piston suits pumps rated around 15 L/min at 200 bar (2900 psi).
- Match rotation regime. Confirm 1750 rpm (or 1450 rpm for 50 Hz variants) against your drive.
- Inspect seals and valves at the same time. Replacing the piston without new seals usually shortens service life.
- Plan for duty cycle and fluid. Aggressive chemicals or high-temperature fluids accelerate wear.
- Source genuine. Counterfeit plungers cause premature seal failure and pressure loss.
Product selection ladder: Interpump pumps and spares
| Level | Product | Flow | Pressure | Power | Best for |
|---|---|---|---|---|---|
| Entry / compact | Inter[[PRODUCT:TS1331-000|pump TS1331 | 13 L/min | 120 bar | 2.94 kW | Light cleaning, 1450 rpm duty |
| Mid-range | Inter[[PRODUCT:T01321-000|pump T1321 | 15 L/min class | 200 bar class | 5.73 kW class | General industrial cleaning |
| Mid-range (alt) | Inter[[PRODUCT:T09281S0U-000|pump T9281 L | Catalog class | Catalog class | Catalog class | Rebuilds and replacements |
| Heavy duty | Interpump T2830Y SX Pump with 53R Motor | 30 L/min | 275 bar | 15.44 kW (21 hp) | High-flow industrial duty |
| Accessory | Interpump 56C Flexible Coupling | — | — | — | Motor-pump alignment |
Step up the ladder when your duty cycle exceeds the entry pump's continuous rating, when you need higher flow for multi-gun operation, or when pressure requirements exceed 200 bar. Step down when portability and 50 Hz supply constraints dominate.
Why source from 3G Electric
3G Electric stocks 4,007+ products across 14 industrial departments — pumps, controls, combustion, pneumatics, and more — with 35+ years of application experience. We supply genuine Interpump spares and pumps Worldwide with export documentation, incoterms-neutral shipping, and technical support to confirm fitment before you buy.
We are a distributor and supplier, not an authorised dealer for every brand we carry. That means we tell you honestly whether a part fits — and if it doesn't, we find the one that does.
Key takeaways
- The 51.0401.09 W1210 piston D. 18x25 is an 18 mm x 25 mm Interpump plunger spare for pumps rated around 15 L/min at 200 bar (2900 psi), 1750 rpm.
- Always confirm pump model, serial, and piston diameter before ordering — cross-family fitment is not guaranteed.
- Replace seals and valves alongside the piston for full service life.
- 3G Electric supplies genuine Interpump spares Worldwide with export documentation and technical support.
Frequently asked questions
What pump does the 51.0401.09 W1210 piston fit?
It fits Interpump high-pressure pump families using an 18 mm x 25 mm plunger, typically rated around 15 L/min at 200 bar (2900 psi) and 1750 rpm. Confirm against your pump nameplate or serial before ordering.
How do I know if my piston needs replacing?
Common signs are falling discharge pressure, pulsation, water in the oil, or visible scoring on the plunger. If pressure drops below rated output despite good valves and seals, the piston is the likely cause.
Can I buy the 51.0401.09 piston in Worldwide markets?
Yes. 3G Electric ships Interpump spares Worldwide with export documentation and incoterms-neutral supply. Lead times depend on destination and stock; request a quote for current availability.
Does 50 Hz vs 60 Hz affect piston choice?
No — the piston diameter is fixed. However, 50 Hz motors run at 1450 rpm and 60 Hz at 1750 rpm, which changes flow and pressure output. Match the piston to the pump frame, not the supply frequency.
Should I replace all three pistons at once?
Yes, in most cases. Triplex pumps wear evenly, and replacing one piston alone can cause imbalance and premature failure of the others. Replace the full set with new seals and valves.
Is the 51.0401.09 piston compatible with the Interpump T2830Y?
Not necessarily. The T2830Y SX runs 30 L/min at 275 bar and uses a different piston diameter. Always verify fitment against the specific pump model before ordering.
Get a quote
Contact 3G Electric for pricing, sizing assistance, and technical support on the 51.0401.09 InterpumpGroup W1210 piston D. 18x25 and the full Interpump pump range. Send us your pump model and serial, and we'll confirm fitment and Worldwide delivery options.
