The HQ4278 is an AS568-278 black Buna-N (Nitrile) 70 Shore A Quad-Ring with an inside diameter of 11.984 in (304.39 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 12.262 in (311.45 mm). This quad-ring provides a dual sealing band on each contact face for improved reliability.
Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, an economical choice for high-volume maintenance programs. It resists hydraulic fluids, greases and lubricants, and petroleum-based oils. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Exposure to strong acids or polar solvents will shorten service life. The profile itself contributes lower compressive load required to achieve a seal and a parting line located away from the sealing surface.
Maintenance and OEM teams specify it across general industrial maintenance, agricultural equipment, and construction equipment.
Reference part number HQ4278 when ordering; the item is sold individually. Application requirements vary, so validate compatibility with your process conditions prior to installation.
Description *4278-366Y MINNESOTA RUBBER QUAD RING
Actual Inside Diameter 11.984 inch (304.39 mm)
Actual Outside Diameter 12.262 inch (311.45 mm)
Actual Cross Section 0.139 inch (3.53 mm)
Measurement System Imperial
Product Category O-Rings - Square/Quad - Premium