Q-257 BUNA 70 Q RING

APG stocks the QH70257, an AS568-257 black Buna-N (Nitrile) 70 Shore A Quad-Ring with an inside diameter of 5.859 in (148.82 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 6.137 in (155.88 mm). A quad-ring uses a four-lobed profile to create two sealing surfaces per side, reducing the squeeze needed to seal.

Buna-N (Nitrile) delivers an economical choice for high-volume maintenance programs, reliable performance in both static and dynamic service. The material holds up against petroleum-based oils, propane and butane, and many alcohols. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or ketones. The profile itself contributes resistance to the spiral twisting that defeats round-section rings and lower compressive load required to achieve a seal.

You will find this material specified across agricultural equipment, hydraulic and pneumatic systems, and construction equipment.

QH70257 ships individually. Unit weight is approximately 5.54 g and nominal inside diameter is listed as 5 7/8 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.