Nitrile Rubber Gaskets (BS2751)

Why choose BS2751 Nitrile for oil resistant sealing?

Nitrile remains the standard choice wherever a gasket needs to cope with oils and hydrocarbons, and this range covers that need across five hardness options rather than a single fixed spec. All five grades share the same core chemical resistance profile: good to excellent resistance to water and alkalis, good resistance to dilute acids and bases, and moderate resistance to hydrocarbons and solvents. Ozone resistance is poor throughout the range, which is typical for nitrile and worth factoring in if the application involves prolonged outdoor exposure.

Manufacturing to BS2751 means the material performs consistently no matter which manufacturer supplies it, so specification stays reliable even if your supply chain changes. Volume swelling tests also confirm the oil resistance in practice, with the harder grades (BA60, BA70, BA80) swelling by only 5% in ASTM 5 oil and 20% in IRM903 oil after 70 hours, while the softer BA40 and BA50 grades swell slightly more at 10% and 30% respectively.

Choosing between the five grades comes down to hardness, strength and flexibility. BA40 is the softest at 40° Shore A with the highest elongation at 600%, suited to applications needing maximum conformability. BA50 through to BA80 step up in hardness and tensile strength as you go, with BA80 offering the highest tensile strength at 13 MPa and the least elongation at 325%, better suited to applications needing a firmer, more dimensionally stable seal.

One honest limitation across the whole range: none of these grades are suited to prolonged ozone or UV exposure, and hydrocarbon resistance is moderate rather than excellent, so heavier duty fuel or solvent exposure may call for a higher grade nitrile instead.

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