Mr O-Ring 234 Viton O-Ring 90A 3in ID Pack of 25 - High Temp Seal

In this review the Mr O-Ring 234 Viton O-Ring is evaluated for technicians, mechanics and hobbyists who need a small, durable seal that resists fuels and high temperatures. The bottom line: this 90A durometer Viton o-ring in a 25-pack offers dependable chemical and heat resistance for a wide range of sealing tasks, making it a useful parts-bin item for anyone working with petroleum products, fuels, hydraulic fluids or high-temperature air systems.

Key Features

• Material: Made from Viton (fluorocarbon rubber), the compound provides excellent resistance to mineral oil, fuels and many organic solvents, which reduces seal failures in aggressive environments.
• Durometer: The 90A hardness keeps the ring firm under compression, offering reliable sealing where a stiffer elastomer is required to resist extrusion and maintain shape.
• Temperature range: Rated from -26C to 232C (-15F to 450F), the o-ring works across broad service temperatures encountered in engine bays, hot process lines and heated enclosures.
• AS568 sizing: Nominal 3in ID, 3-1/4in OD, 1/8in CS with actual dimensions close to spec, so it fits standard AS568 mounting grooves and replacements without fuss.
• Pack quantity: Supplied as a pack of 25, which keeps replacement parts on hand for routine maintenance and reduces downtime when multiple seals are required.

Who It's For

This o-ring is best for maintenance technicians, automotive and marine mechanics, and equipment builders who need a resilient seal that tolerates fuels, oils and high temperatures. The chemical resistance of Viton makes it a solid choice for applications exposed to aromatics, diesel blends, silicone oils and hydraulic fluids.

It is less suitable for low-cost, low-temperature consumer projects where softer elastomers would seal better at very low compression, or for applications requiring FDA food-grade elastomers; buyers needing food-safe or very soft materials should look elsewhere.

Pros & Cons

Pros

• Excellent chemical and heat resistance from the Viton FKM formulation.
• Consistent fit with AS568 nominal and actual dimensions that match common grooves.
• Durable 90A durometer reduces extrusion and maintains sealing force under pressure.
• Bulk pack of 25 keeps spares ready for maintenance cycles.

Cons

• Higher durometer means it may not seal as well in very low-pressure or low-compression applications compared with softer o-rings.

Specifications

Material	Viton (fluorocarbon rubber, FKM)
Durometer	90A
Nominal dimensions	3 in ID, 3-1/4 in OD, 1/8 in CS
Actual dimensions	2.984 in ID, 3.262 in OD, 0.139 in CS
Metric dimensions	75.79 mm ID, 82.85 mm OD, 3.53 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	25 pieces

Our Verdict

The Mr O-Ring 234 Viton o-ring is a practical, service-grade seal for professionals who need reliable chemical and high-temperature performance. Its 90A hardness and AS568-compatible sizing make it a dependable replacement part for engines, pumps and hydraulic systems, and the 25-piece pack provides good value for workshops that perform regular maintenance.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes. The Viton compound is rated for petroleum products including gasoline, diesel and many fuel blends.

Will the 90A hardness work for hydraulic seals?
Yes, the 90A durometer is suitable for many hydraulic sealing points where a firmer elastomer helps resist extrusion; confirm groove clearance for best fit.

Do these o-rings meet AS568 sizes?
Yes, the product is made to the AS568 nominal size series with the listed actual dimensions for reliable replacement.