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 the Ø18 x 25 mm piston assembly used in Interpump W-series plunger pumps, and it is the correct replacement when a pump loses pressure, shows seal weep, or is being rebuilt on a scheduled service interval. Buyers worldwide source it as a genuine Interpump spare to restore rated flow and pressure without replacing the whole pump.
What is the Interpump W1210 piston D. 18x25?
A piston (plunger) for an Interpump W-series pump is the reciprocating ceramic or hardened-steel element that displaces water inside the manifold, converting motor rotation into flow and pressure. The 51.0401.09 designation identifies the InterpumpGroup W1210 variant with an 18 mm diameter and 25 mm stroke-related length, matched to the pump's seal pack and manifold bore.
Interpump Group is one of the world's dominant manufacturers of high-pressure plunger pumps, and its W-series pumps are widely used in pressure washers, reverse-osmosis systems, misting, and industrial cleaning. Because the piston is a wear item, correct identification of the 51.0401.09 part number is the difference between a pump that holds 200 bar and one that bleeds pressure at the seal.
How does a W-series piston work?
The piston reciprocates inside the manifold, drawing water through the inlet valve on the downstroke and pushing it through the outlet valve on the upstroke. Seals and O-rings isolate the piston from the crankcase, so piston wear typically shows first as pressure loss or water in the oil.
On a pump rated 15 L/min at 200 bar (2900 psi) and 1750 rpm, the piston is sized so that displacement per stroke matches the pump's rated flow. Fitting a piston of the wrong diameter changes both flow and pressure characteristics, which is why the 18x25 dimension must match the original.
Spec table: 51.0401.09 InterpumpGroup W1210 piston D. 18x25
| Attribute | Value |
|---|---|
| Part number | 51.0401.09 |
| OEM | Interpump Group |
| Pump family | W1210 (W-series) |
| Component type | Piston / plunger |
| Piston diameter | 18 mm |
| Piston length | 25 mm |
| Typical pump flow | 15 L/min (3.96 US gpm) |
| Typical pump pressure | 200 bar (20 MPa / 2900 psi) |
| Typical rotation | 1750 rpm |
| Typical 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 |
Note: the flow, pressure, power, and dimension figures above describe the W-series pump platform the piston serves, not the piston itself. Always confirm the piston diameter against your pump nameplate before ordering.
Which applications use the W1210 piston?
The W-series platform is used across industrial cleaning, reverse osmosis, misting and humidification, car wash, and food-processing washdown. In each case the piston is a consumable, replaced on hours-run or when pressure falls below specification.
- Industrial pressure washers and cold-water cleaning skids
- Reverse-osmosis and membrane filtration feed pumps
- Misting, fogging, and humidification systems
- Car wash and vehicle cleaning bays
- Food and beverage washdown (stainless manifold variants)
How to select the right Interpump piston
- Confirm the pump model. Read the Interpump nameplate on the crankcase — W1210, T-series, or TS-series — before matching a piston part number.
- Match the piston diameter. The 18x25 dimension must match the original; a different diameter changes flow and pressure.
- Check the seal kit. Replace seals, O-rings, and valves at the same time as the piston to avoid repeat teardown.
- Verify duty cycle. Continuous-duty RO and misting duty wears pistons faster than intermittent washdown.
- Confirm water quality. Abrasive or high-TDS water accelerates piston and seal wear; specify filtration upstream.
- Check rotation and drive. Confirm 1750 rpm (50 Hz) or 1450 rpm (60 Hz) motor pairing and correct coupling.
Product selection ladder: Interpump pumps and spares
The table below places the W1210 piston in context with representative Interpump pumps and accessories stocked by 3G Electric, from compact light-duty units to high-power industrial pumps.
| Product | Type | Flow | Pressure | Power | Weight |
|---|---|---|---|---|---|
| Inter[[PRODUCT:TS1331-000|pump TS1331 | Plunger pump | 13 L/min | 120 bar | 2.94 kW | — |
| Inter[[PRODUCT:T01321-000|pump T1321 | Plunger pump | — | — | — | — |
| Inter[[PRODUCT:T09281S0U-000|pump T9281 L | Plunger pump | — | — | — | — |
| Interpump T2830Y SX Pump with 53R Motor | Pump + motor | 30 L/min (7.92 US gpm) | 275 bar | 15.44 kW (21 hp) | 18.5 kg |
| Inter[[PRODUCT:AB0150CD-000|pump AB150 PTO R | PTO pump | — | — | — | — |
Step up the ladder when your duty cycle moves from intermittent cleaning to continuous industrial service: the T2830Y SX delivers 30 L/min at 275 bar and 15.44 kW, roughly double the flow of a compact TS1331. For rebuilds, pair the piston with Interpump Flexible Coupling 56C and Interpump Variojet Kit with 125 Nozzle to complete the service.
Why source Interpump spares from 3G Electric?
3G Electric stocks 4,007 products across 14 industrial departments — machining, electrical, power transmission, pumps, controls, and more — with deep specialist expertise in combustion, pumps, and controls. We interpret your demand, confirm the correct part number, and quote it with export documentation for worldwide delivery.
- 4,007+ products in stock across pumps, spares, valves, and accessories
- 35+ years of industrial supply experience
- Technical support to confirm piston, seal, and valve fitment
- Worldwide shipping with export documentation experience
- Incoterms-neutral supply — FOB, CIF, DAP, or EXW as required
According to Interpump Group S.P.A. technical documentation (SS3C2015, dated 3/21/2026): "Male shaft (key) - (plugs) - OUT OF PRODUCTION."
This note is a reminder that Interpump periodically supersedes or discontinues specific pump configurations. Always confirm current part availability and any superseding part number with your supplier before ordering.
Frequently asked questions
What is the 51.0401.09 InterpumpGroup W1210 piston used for?
It is the Ø18 x 25 mm replacement piston for Interpump W-series plunger pumps, used in pressure washers, reverse-osmosis systems, misting, and industrial cleaning. It restores rated flow and pressure when the original piston wears.
How do I confirm the piston fits my pump?
Read the Interpump nameplate on the crankcase, confirm the pump family (W1210, T-series, TS-series), and match the 18 mm diameter and 25 mm length against the original piston. When in doubt, send the pump serial to 3G Electric for verification.
What is the difference between a piston and a plunger?
In Interpump terminology the terms are often used interchangeably for the reciprocating element inside the manifold. Both displace water to generate flow and pressure; the 51.0401.09 is the specific 18x25 mm element for the W1210.
Can I buy the 51.0401.09 piston in Worldwide?
Yes. 3G Electric supplies Interpump spares worldwide with export documentation, incoterms-neutral terms, and both 50 Hz and 60 Hz pump configurations. Contact us for a quote with lead time to your region.
Should I replace seals and valves at the same time?
Yes. Piston wear usually accompanies seal and valve wear. Replacing the piston, seals, O-rings, and valves in one teardown reduces downtime and prevents repeat labour on the same pump.
What pressure and flow does the W1210 platform deliver?
The W-series platform typically delivers 15 L/min (3.96 US gpm) at 200 bar (20 MPa / 2900 psi) and 1750 rpm, drawing about 5.73 kW (7.8 hp). Confirm against your specific pump nameplate.
Key takeaways
- The 51.0401.09 InterpumpGroup W1210 piston D. 18x25 is a Ø18 x 25 mm replacement piston for Interpump W-series pumps.
- Confirm pump model, piston diameter, and seal kit before ordering to avoid repeat teardown.
- W-series pumps typically run 15 L/min at 200 bar (2900 psi) and 1750 rpm.
- 3G Electric stocks 4,007+ products and supplies Interpump spares worldwide with export documentation.
- Pair the piston with seals, valves, and couplings for a complete rebuild.
Contact 3G Electric for quotes, sizing assistance, and technical support on the 51.0401.09 InterpumpGroup W1210 piston D. 18x25 and the full Interpump pump and spare range. Send your pump nameplate or serial and we will confirm fitment and lead time to your region.
