Plunger 20mm L-119,6mm

The 20 mm long plunger (piston) for AQ pumps is a working element of a high-pressure pump responsible for generating pressure in the pumping section. In industrial washer service, it is replaced when the working surface is worn, mechanically damaged, or during a full pump refurbishment.

MPN / reference: 40505
Weight: 0.28 kg
Dimensions / size: 2 × 11.7 × 1.2 cm (L ~ 117 mm)

APPLICATION

Used in AQ pump servicing, including:

• replacing the plunger/piston in the AQ pump working section,
• pump refurbishment after long operation in industrial washers,
• repairs after operating with contaminated water or insufficient water supply (risk of scuffing/seizure),
• pump overhaul to eliminate performance drops and unstable operation.

SYMPTOMS - WHEN IT’S WORTH REPLACING

Typical signs of plunger wear or damage:

• drop in working pressure and reduced system output,
• jet pulsation and pressure fluctuations (after ruling out nozzle and valves),
• leaks around the pump head due to accelerated seal wear,
• unusual friction/noise in the pump working section,
• scratches, pitting, or surface damage found after disassembly.

HOW TO CHOOSE THE RIGHT PART

Selection must be precise, because the part works within tight tolerances with seals and guides:

• by manufacturer MPN / reference: 40505,
• by dimensions: 20 mm diameter and the “long” version (in practice, length and geometry are critical),
• by comparison with the removed part: compare length, diameter, and how it mates with the seals.

Correct fit affects pump tightness and service life - the wrong plunger can cause fast seal wear or pressure loss.

COMPATIBILITY

Part described for AQ pumps. Confirm compatibility by MPN 40505 and dimensional parameters using the pump documentation/parts list. Do not select only by “20 mm long” without verifying the reference and matching the removed part.

[faq]

Does “20 mm long” mean it fits every 20 mm AQ pump?|Not always. Fit also depends on the exact length and geometry used in a given pump variant. The safest method is selection by MPN 40505 and comparison with the removed plunger.
Should I replace seals when replacing the plunger?|Often yes-worn seals can quickly damage a new plunger, and a new plunger may not seal correctly with old parts. Final decision depends on the condition of seals and guides after inspection.
Can I use an aftermarket plunger?|Only with full match of diameter, length, geometry, and working-surface quality. Tolerances are critical in pump working parts, so use the MPN and pump specification as the reference.

[/faq]