AS568-212 HNBR (HSN) Highly Saturated Nitrile 70 Duro O-Ring

Dimensions: 1/8" CS x 7/8" ID x 1-1/8" OD

The AS568-212 is a 70A durometer HNBR O-Ring in Green, molded from Highly Saturated Nitrile also called HSN or hydrogenated nitrile. It measures 0.139" cross-section by 0.859" ID by 1.137" OD and seals from -40F to +300F. HNBR keeps the oil and fuel resistance of standard nitrile and adds better heat, ozone and wear life, so it holds up in automotive air conditioning, sour gas and hot oil where plain Buna-N gives out. This size is stocked in the USA and ships same day from The O-Ring Store LLC, an ISO 9001:2015 certified distributor.

Stop leaks in hot oil, fuel and refrigerant systems with the AS568-212 HNBR O-Ring. This 70A durometer seal handles petroleum oils, R-134a air conditioning refrigerant and sour gas across -40F to +300F, and it shrugs off ozone and wear far better than standard nitrile. That makes it a smart upgrade anywhere a Buna-N O-Ring keeps hardening, cracking or wearing out too soon.

Operating Temperature: -40 to +300F (-40 to +149C)

Material and Performance Details

HNBR, or HSN, starts as standard nitrile and gets hydrogenated to saturate the butadiene in the polymer chain. That one change buys you better thermal stability, higher tensile strength, more resistance to wear and extrusion, and much longer ozone and oxygen life, all while keeping nitrile's strong oil and fuel resistance. It is peroxide cured for good compression set and heat life, and it is best known for standing up to automotive A/C refrigerants like R-134a. Shelf life runs about 15 years under ARP5316. The 70A durometer is the standard hardness for most sealing jobs and gives good squeeze without going brittle.

Recommended for:

• Petroleum oils and fluids
• Automotive air conditioning refrigerants (R-134a)
• Hydrogen sulfide (H2S) and sour gas
• Carbon dioxide (CO2)
• Gasoline
• Hydraulic fluids
• LP gases
• Silicone greases and oils
• Di-ester base lubricants (MIL-L-7808)
• Ethylene glycol base fluids (Hydrolubes)

Not recommended for:

• Halogenated hydrocarbons (carbon tetrachloride, trichloroethylene)
• Nitro hydrocarbons (nitrobenzene, aniline)
• Phosphate ester hydraulic fluids (Skydrol, Fyrquel, Pydraul)
• Ketones (MEK, acetone)
• Sunlight and UV
• Weather
• Strong acids
• Automotive brake fluid

Sizes and Measurements

• Dimensions: 1/8" CS x 7/8" ID x 1-1/8" OD
• Actual: 0.139" CS x 0.859" ID x 1.137" OD
• Metric: 3.53mm CS x 21.82mm ID x 28.88mm OD
• Part Number: H70212
• AS568 Dash Number: -212
• Cross-references: Parker 2-212 (3.53mm CS / 0.139" CS)

Applications and Use Cases

HNBR O-Rings earn their keep wherever petroleum fluids meet heat. You will find them in automotive air conditioning and refrigerant seals, timing and engine components, hydraulic systems, industrial machinery and oilfield equipment that sees sour gas. When a standard nitrile seal keeps hardening in the heat or wearing out too fast, HNBR is the step up that lasts.

• Automotive air conditioning and R-134a refrigerant seals
• Engine, timing and transmission components
• Hot oil and hydraulic systems
• Oilfield equipment in sour gas (H2S) service
• Pumps, valves and compressors
• Industrial machinery in harsh high-heat service
• Fuel and gasoline system seals

Key Specifications

• Material: HNBR (Highly Saturated Nitrile, HSN)
• Durometer: 70A Shore A
• Color: Green
• Cure System: Peroxide cured
• Temperature Range: -40 to +300F (-40 to +149C)
• Standards: AS568 sizing, SAE J200 / ASTM D2000
• FDA: No

Why Buy from The O-Ring Store LLC

The O-Ring Store LLC is an ISO 9001:2015 certified distributor with USA stock for fast shipping. Most in-stock sizes ship the same day. We handle custom sizes and can send lot traceability and documentation when you need it. Every order gets checked through our Olypsys® scan-based quality system before it leaves the building. Fair pricing, real people and no runaround. We make getting O-Rings easy!

Frequently Asked Questions

Q: What are the exact dimensions of the AS568-212 O-Ring?
A: The AS568-212 has a 0.139" cross-section (3.53mm), a 0.859" inside diameter (21.82mm) and a 1.137" outside diameter (28.88mm).

Q: How is HNBR better than standard Buna-N?
A: HNBR keeps nitrile's oil and fuel resistance and adds better heat, ozone and wear life. It seals continuously to +300F where standard nitrile tops out around +250F, and it is the go-to for R-134a air conditioning and sour gas service.

Q: What is the Parker equivalent of the AS568-212 O-Ring?
A: The Parker cross-reference for the AS568-212 is the Parker 2-212. Both share the 0.139" (3.53mm) cross-section and 0.859" (21.82mm) inside diameter under the AS568 standard.