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70 Durometer Buna-N O-Ring, Inch OD, 1-1/8 Inch ID, 0.21 Inch Width

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Description & Features

This 70 Durometer Buna-N O-Ring offers reliable sealing performance in hydraulic applications. Constructed from durable Buna-N (Nitrile) rubber, this O-ring provides excellent resistance to oil, fuels, and other common industrial fluids.

With a nominal OD of 1-1/2 inches, a nominal ID of 1-1/8 inches, and a width of 0.21 inches, this Hercules Sealing Products O-ring is suitable for a wide range of sealing tasks. It maintains its sealing properties in temperatures ranging from -40°F to 240°F.

SKU: A-320

Supplier Part Number (MPN): 568-320

Alternate Part Numbers: C1CF61, MI-08740489, MINO-00407X90489

Specifications

Brand
HERCULES® SEALING PRODUCTS
Color
Black
Cross Section Shape
Round
Dash Size
320
Durometer
70A
Inside Diameter
1-1/8 in
Material
Buna-N
Series
568 Series
Suitable For Use With
Hydraulic Cylinders
System of Measurement
Imperial

Product Questions & Answers (3)

Question by: Carl M on Dec 18, 2025, 12:40 PM
Reckon these'd hold up alright in a hydraulic system running some hot oil?
Answer by: Customer Support on Dec 20, 2025, 6:10 AM
These Buna-N O-rings are able to handle temperatures from -40°F up to 240°F, so they should work well in many hydraulic applications where the oil doesn't exceed that upper limit.
Question by: Hank R on Feb 28, 2026, 5:20 PM
got an AS568-320 groove, is this the right o-ring size or am i gonna be fighting it
Answer by: Customer Support on Mar 2, 2026, 6:58 AM
For dash size -320, the nominal dimensions are 1-1/8 inch ID, 1-1/2 inch OD, and 3/16 inch nominal width. The actual measurements are listed as 1.10 inch ID, 1.52 inch OD, and 0.21 inch width, so it is a -320 size ring with those actual dimensions.
Question by: Daryl P on Jan 22, 2026, 9:44 PM
temperature range on these - does it go below freezing? got equipment running outside through winter and need something that won't crack up on me
Answer by: Customer Support on Jan 24, 2026, 5:16 PM
Rated down to -40°F, so cold weather operation is well within range. On the upper end it holds up to 240°F, which covers most hydraulic system heat loads without issue. Buna-N at 70 durometer is a pretty standard choice for outdoor equipment that sees real seasonal swings.

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