O-rings are circular rubber seals, first used as sealing elements for steam engine cylinders in the mid-19th century.
They are simple in structure, low in cost, and provide reliable sealing, capable of withstanding pressures of tens of megapascals. They are suitable for static sealing and dynamic applications such as hydraulic cylinder pistons. Materials include nitrile rubber and fluororubber. As a bidirectional sealing element, they achieve self-sealing through initial compression and system pressure. The compression deformation rate is 15%-30% for static sealing and 9%-25% for dynamic sealing. During installation, the elongation rate (≤6% for bores) or circumferential compression (≤3% for shafts) must be controlled. For pressures exceeding 5 MPa, a retaining ring is recommended.
Material selection must comprehensively consider the medium, temperature, and pressure, conforming to standards such as GB 1235-76 and AS568, with technical specifications referring to HG/T 2579-2008, and meeting the special certification requirements of industries such as food, automotive, and aerospace. The operating temperature range is -55℃ to 250℃, and it possesses resistance to oil, acids, alkalis, and chemical corrosion.