Mr O-Ring 341 Viton O-Ring 90A Durometer, 3-1/2 in ID (Pack of 25)

In this review the Mr O-Ring 341 Viton O-Ring is evaluated for technicians and maintenance pros who need reliable chemical and temperature resistance in standard AS568 sizes. The bottom line: it is a durable, high-hardness fluorocarbon seal best for applications exposed to fuels, oils, high temperatures and ozone. The reviewer found the 90A durometer construction and Viton material deliver consistent sealing performance across a wide temperature range, making it a practical choice when long-term resistance to petroleum products and high heat is the priority.

Key Features

• Material: Viton fluorocarbon rubber offers exceptional resistance to fuels, mineral oils and many organic solvents, which reduces seal degradation in chemical environments.
• Hardness: 90A durometer provides a firm, wear-resistant seal that maintains shape under compression for long service life in static and some dynamic uses.
• Size accuracy: Nominal 3-1/2 in ID with actual dimensions close to 3.475 in ID and 3.895 in OD for dependable fitting to AS568 size standards.
• Temperature range: Rated from -26C (-15F) to 232C (450F), allowing use in very hot air, high-temperature equipment and cold conditions without rapid loss of properties.
• Pack quantity: Sold as a pack of 25 which is convenient for service shops and projects that require multiple replacement seals.

Who It's For

This o-ring suits maintenance technicians, hydraulic and pneumatic service shops, and anyone replacing seals in fuel systems, engines, or heated equipment where exposure to petroleum, diesel blends, silicone oils or harsh solvents is expected. The high temperature tolerance and Viton chemistry make it appropriate for industrial settings where ozone and weather resistance matter.

It is less suited for soft-seal applications that require a very low durometer for gentle compression or for specialized elastomers outside the Viton family when extreme chemical compatibility beyond Viton is required. If a softer, more flexible o-ring is needed for delicate dynamic seals, consider a lower durometer option.

Pros & Cons

Pros

• High chemical resistance to fuels, oils and many solvents, so it lasts longer in aggressive media.
• Wide operating temperature range that supports both high-heat and cold applications.
• 90A hardness gives strong dimensional stability and wear resistance in service.
• Pack of 25 provides good value for workshops needing multiple replacements.

Cons

• The 90A durometer is relatively hard, which may be unsuitable for seals that require softer material to accommodate surface irregularities.
• Viton is a premium material and may cost more than general-purpose elastomers for noncritical applications.

Specifications

Our Verdict

The Mr O-Ring 341 Viton 90A is a practical, value-minded choice for professionals who need durable seals that resist fuels, oils and high temperatures. Its firm 90A hardness and AS568-compatible size make it a dependable replacement option for industrial maintenance and fuel system applications, offering good longevity for those environments.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes, Viton is formulated to resist petroleum products including gasoline, diesel and many blended fuels.

Do these meet standard AS568 sizes?
Yes, the 341 designation corresponds to the AS568 size range and the actual dimensions are provided for accurate fitting.

What environments are unsuitable for Viton?
Viton performs poorly with certain ketones and some highly concentrated amines; for those fluids a different elastomer may be required.