O-Rings Parts
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O-rings seal connections throughout a pressure washer — pump heads, quick-connects, hose fittings, and injector ports — and material matters as much as size. Buna-N (nitrile) is the standard general-purpose material; Viton handles higher temperatures and chemical exposure better, which matters for hot-water units and detergent injection systems.
O-Rings Buying Guide
Size and durometer both matter
Two o-rings can share the same outer dimension but use different cross-section thickness or hardness (durometer) — matching your pump or fitting manufacturer's exact part spec avoids a seal that looks right but leaks under pressure.
Buna-N vs. Viton
Buna-N is the cost-effective default for cold and ambient-temperature water systems. Viton costs more but resists heat and chemical degradation far better, which is why it's the standard choice for hot-water pressure washers and chemical injector seals.
O-Rings FAQ
Can I substitute a similar-size o-ring if I don't have the exact part number?
It will often seal temporarily, but a mismatched cross-section or durometer wears faster and is more likely to extrude or leak under pressure cycling. For anything on the pressure side of the pump, match the exact spec.