AS568-111 B50 (NBR) Buna-N Nitrile 50 Duro O-Ring

Dimensions: 7/16" ID x 5/8" OD x 3/32" CS

The AS568-111 is a Buna-N (Nitrile) 50A Durometer O-Ring with an inside diameter of 0.424 inches and a cross-section of 0.103 inches. It is built for low-pressure and vacuum sealing on soft, uneven or lightly loaded surfaces where an extra-soft seal conforms better than standard nitrile. This O-Ring is stocked and shipped same-day by The O-Ring Store LLC, an ISO 9001:2015 certified distributor.

Seal low-pressure, vacuum and imperfect surfaces that a harder O-Ring leaks right past with the AS568-111 Buna-N (Nitrile) O-Ring. This 50A Durometer seal molds to rough or out-of-round surfaces with less squeeze force and still resists petroleum oils, fuels and hydraulic fluids from -40F to +225F. That makes it a solid pick for the jobs below, and a reliable replacement when a lesser O-Ring swells, cracks or takes a set.

Operating Temperature: -40 to +225F (-40 to +107C)

Material and Performance Details

Buna-N, also known as Nitrile or NBR, is the workhorse of the O-Ring world. It gives strong resistance to petroleum oils, fuels and hydraulic fluids at a fair price, which is why it fits so many everyday sealing jobs. This is the 50 Durometer version, an extra-soft nitrile that runs more flexible and more pliable than the standard 70 Duro. The softer material presses down into low spots, tool marks and out-of-round grooves that a harder O-Ring would bridge right over, so it forms a tight seal with less closure force and lower squeeze. That is a real advantage on low-pressure and vacuum work, on lightweight or plastic housings, on thin-wall parts and on hand-assembled joints where you do not have a lot of bolt load to seat the seal. And it keeps every bit of the oil, fuel and hydraulic-fluid resistance of standard nitrile, so you give up nothing on chemical compatibility to gain the softer, more forgiving seal. The 50A Durometer sits on the soft, pliable end of the scale, so it seats with light closure force and molds into the sealing surface for a tight low-pressure seal.

• Excellent resistance to: petroleum oils, hydraulic fluids, water, silicone greases, ethylene glycol, gasoline, diesel, LP gases and mineral oils
• Limited capability with: Skydrol, high ozone, sunlight and dilute acids
• Not compatible with: ketones such as MEK and acetone, esters, chlorinated hydrocarbons, strong acids, ozone and glycol brake fluid

Sizes and Measurements

• Dimensions: 7/16" ID x 5/8" OD x 3/32" CS
• Actual: 0.424" ID x 0.63" OD x 0.103" CS
• Metric: 10.77mm ID x 16mm OD x 2.62mm CS
• Part Number: B50111
• AS568 Dash Number: -111
• Cross-references: Parker 2-111 (2.62mm CS / 0.103" CS)

Applications and Use Cases

Extra-soft 50 Duro Buna-N O-Rings earn their keep wherever a standard seal is too stiff to close. They seal low-pressure and vacuum systems, lightweight and plastic housings, thin-wall fittings and hand-tightened joints, and they conform to scratched, rough or out-of-round grooves that a firmer O-Ring would leak past. They handle petroleum oils, diesel and gasoline the same as standard nitrile, so you keep the oil and fuel resistance while gaining a softer, more forgiving seal. Keep them out of high-pressure jobs where a soft O-Ring can extrude, and away from ozone, sunlight and brake fluid, and they will run a long time.

• Low-pressure and vacuum seals
• Lightweight and plastic housings
• Thin-wall fittings and low-bolt-load flanges
• Rough, scratched or out-of-round sealing surfaces
• Hand-assembled and low-torque joints
• Static face and flange seals
• Oil and fuel systems that need a softer seal

Key Specifications

• Material: Buna-N (Nitrile)
• Durometer: 50 Shore A
• Color: Black
• Temperature Range: -40 to +225F (-40 to +107C)

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 delivery. Most in-stock items ship the same day. We handle custom sizes, and we can send full 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 AS568-111 O-Ring?
A: The AS568-111 O-Ring has an actual inside diameter of 0.424 inches (10.77mm), a cross-section of 0.103 inches (2.62mm) and an outside diameter of 0.63 inches (16mm).

Q: Is this 50 Duro Buna-N compatible with oil and fuel?
A: Yes. Nitrile resists petroleum oils, hydraulic fluids, gasoline and diesel, which is why it is the standard pick for most oil and fuel sealing. The 50 Duro extra-soft version keeps that same oil and fuel resistance and just seals with a softer, more forgiving squeeze.

Q: What is the Parker equivalent of the AS568-111 O-Ring?
A: The Parker cross-reference for the AS568-111 is the Parker 2-111. Both share the same 0.103-inch (2.62mm) cross-section and 0.424-inch (10.77mm) inside diameter per the AS568 standard.