**4390-366Y MINNESOTA RUBBER QUAD RING

This quad-ring is supplied in AS568-390 black Buna-N (Nitrile) 70 Shore A supplied with an inside diameter of 20.953 in (532.21 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 21.373 in (542.87 mm), catalogued under part number HQ4390. It resists spiral failure in reciprocating service thanks to its multi-lobe geometry.

Buna-N (Nitrile) offers reliable performance in both static and dynamic service, an economical choice for high-volume maintenance programs. It resists propane and butane, greases and lubricants, and water. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). It is not the right choice where automotive brake fluid or strong acids are present. The profile itself contributes a parting line located away from the sealing surface and two sealing bands per contact face rather than one.

Maintenance and OEM teams specify it across hydraulic and pneumatic systems, construction equipment, and fluid power.

Order part number HQ4390, sold individually. Nominal inside diameter is listed as 21 inch. Check the compound against your process media, pressure and temperature before committing to a design.