Mr O-Ring 349 Viton O-Ring 4-1/2in ID 90A Pack of 10 - High Temp Seal

In this review the Mr O-Ring 349 Viton O-Ring is assessed for technicians, maintenance shops and DIYers who need a reliable high-temperature seal in a common AS568 size. The bottom line: this pack of 10 Viton o-rings stands out for its broad chemical compatibility and wide operating temperature range, making it a practical choice when resistance to fuels, oils and high heat matters most. The review highlights real dimensions, material performance and common applications so you can decide if these 90A durometer seals fit your project.

Key Features

• Material: FKM Viton construction provides excellent resistance to fuels, oils and many solvents for longer seal life in harsh environments.
• Temperature range: Rated from -26C (-15F) to 232C (450F), these o-rings maintain sealing integrity across wide temperature swings.
• Durometer: The 90A hardness balances firmness and flexibility to resist extrusion while still forming an effective static or dynamic seal.
• Size accuracy: Nominal 4-1/2in ID with actual dimensions listed ensures compatibility with fittings that follow AS568 sizing standards.
• Chemical compatibility: Performs well with petroleum products, diesel, biodiesel blends, methanol/ethanol blends, silicone oils and many acids, reducing the need for multiple material types.
• Pack quantity: Supplied as a pack of 10 which is convenient for maintenance spares or small repair jobs.

Who It's For

These o-rings are well suited to mechanics, hydraulic technicians, and industrial maintenance personnel who require a compact supply of durable, high-temperature seals in a common AS568 size. Their resistance to fuels, mineral oils and high heat makes them a sensible choice for engine compartments, pumps, fuel systems and some chemical handling systems.

People who should look elsewhere include those needing extreme low-temperature flexibility below -26C, or applications that require FDA food-grade elastomers or very soft rubbers under 90A durometer. For specialized polymers with unique approvals, a material data sheet comparison is recommended.

Pros & Cons

Pros

• High chemical resistance from Viton material makes these o-rings reliable in contact with fuels and many solvents.
• The wide temperature range supports both high-heat and many everyday automotive or industrial uses.
• Actual dimensions are provided so installers can confirm fit before use.

Cons

• The 90A durometer is relatively firm and may be less forgiving in low-temperature or soft-sealing applications.

Specifications

Brand	Mr O-Ring
Material	Viton (FKM), 90A durometer
Nominal dimensions	4-1/2in ID, 4-7/8in OD, 3/16in CS
Actual dimensions	4.475in ID, 4.895in OD, 0.210in CS
Metric dimensions	113.67 mm ID, 124.33 mm OD, 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack size	Pack of 10

Our Verdict

The Mr O-Ring 349 Viton o-ring pack is a practical, value-oriented choice for professionals who need a durable, high-temperature seal in a common AS568 size. With strong chemical resistance and clearly listed actual dimensions, it suits many automotive and industrial repair tasks, though users needing softer, low-temp elastomers should consider other compounds.

Frequently Asked Questions

Are these o-rings compatible with fuel blends?
Yes, the Viton material performs well with petroleum, diesel, biodiesel blends and fuels blended with methanol or ethanol.

Do these meet AS568 sizing?
Yes, the product is offered to meet size standards defined by AS568 and actual dimensions are provided for confirmation.

What temperature limits should I expect?
The usable range is approximately -26C (-15F) to 232C (450F), suitable for many high-heat applications.