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O-RIngs
O-rings seal hydraulic fittings, pneumatic lines, air-con ports, and pressurised assemblies across workshop equipment and vehicle systems. This range covers metric and imperial sizes in nitrile rubber (NBR), supplied in compartmented assortments so you have the common diameters and cross-sections to hand when a seal fails or you're rebuilding a cylinder, compressor, or coupling.
Showing all 4 results
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Not yet ratedSealeyImperial Rubber O-Ring Assortment 407pc- 407-piece assortment
- Nitrile material
- Partitioned storage box
€47.12€47.60€38.31€38.70 -
Not yet ratedSealeyRubber O-Ring Air Conditioning Assortment 225pc- 225pc metric assortment, 3–22 mm
- Partitioned storage box included
€59.30€59.90€48.21€48.70 -
Not yet ratedSealeyRubber O-Ring Assortment 225pc- 225pc Metric O-ring assortment
- Partitioned storage box
€27.34€27.61€22.23€22.45 -
Not yet ratedSealeyRubber O-Ring Assortment 419pc- 419-piece assortment, nitrile
- ID 3–50 mm, thickness 1.5–3.5 mm
- Partitioned storage box
€47.12€47.60€38.31€38.70
Most workshop O-rings use nitrile rubber (NBR, also called Buna-N), which handles mineral oils, hydraulic fluids, air, and water across a working range of roughly −30 °C to +100 °C. It's compatible with ISO 32 and ISO 46 hydraulic oil, ATF, diesel, and compressed air, but not with brake fluid (DOT 3/4/5.1), petrol, or refrigerant oils — those need specific elastomers (EPDM for brake fluid, HNBR for refrigerant compatibility). Check the fluid compatibility if you're sealing anything outside standard hydraulics or pneumatics.
Cross-section (the O-ring's wire thickness) and inside diameter (ID) both matter. A 2 mm cross-section ring won't seal a 3 mm groove, and an undersized ID will stretch and tear under pressure; an oversized one won't compress enough to fill the gland. Metric assortments cover millimetre sizing (common in European hydraulics and compressed-air fittings); imperial sets cover fractional-inch sizes still used in older British machinery, American-spec compressors, and some refrigeration gear. Air-conditioning assortments include the smaller diameters found in hose barbs, Schrader cores, and manifold ports — if you service A/C systems or refrigeration, you'll need those sizes separately.
Store O-rings out of direct sunlight and away from ozone sources (electric motors, welders). NBR hardens and cracks with UV exposure and ozone attack. Lubricate with a film of the system fluid (hydraulic oil, compressor oil) or silicone grease before fitting — it protects the ring during installation and helps it seat properly. Never use petroleum jelly on hydraulic or pneumatic O-rings; it swells NBR and causes leaks.