Q-256 BUNA 70 Q RING

Ordered as QH70256, this is an AS568-256 black Buna-N (Nitrile) 70 Shore A Quad-Ring built to an inside diameter of 5.734 in (145.64 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 6.012 in (152.7 mm). The quad-ring provides a dual sealing band on each contact face for improved reliability.

The compound resists many alcohols, petroleum-based oils, and water. That behavior comes from the compound itself: Buna-N (Nitrile) delivers low compression set under sustained load, strong abrasion and tear resistance. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with polar solvents or ozone and direct sunlight. 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 hydraulic and pneumatic systems, automotive, and general industrial maintenance.

Reference part number QH70256 when ordering; the item is sold individually. Unit weight is approximately 5.6728 g and nominal inside diameter is listed as 5 3/4 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.