347 Viton O-Ring 75A 4-1/4in ID 4-5/8in OD - Pack of 10

In this review the 347 Viton O-ring (pack of 10) is evaluated for mechanics, hobbyists, and technicians who need a durable seal that resists fuels and heat. The bottom line: this set is best for users who require chemical and temperature resilience in a standard AS568A size and want reliable replacements for fittings like MSA fuel bottles or barrel seals. The reviewer found the material and dimensions straightforward, with the main reason to buy being the combination of a Viton fluorocarbon compound and a practical 75A hardness that balances flexibility and penetration resistance.

Key Features

• Material: Made of Viton fluorocarbon elastomer, it offers strong resistance to fuels, aromatic and aliphatic hydrocarbons, and many chemicals used in industrial applications.
• Temperature range: Rated from -15 degrees F to 400 degrees F, the O-ring is suitable for high-heat environments and cold storage down to the specified limit.
• Shape and fit: The round cross-section provides a dependable seal between overlapping cylindrical surfaces commonly found in hydraulic and plumbing assemblies.
• Durometer: At 75A shore hardness, the compound resists penetration while remaining flexible enough for routine replacement use.
• Standards compliance: Manufactured to match Aerospace Standard AS568A sizing, ensuring compatibility with many standard O-ring grooves and replacements.
• Compatibility: Works with non-flammable hydraulic fuels, silicone oils, chlorinated hydrocarbons, and high vacuum environments for broad application use.

Who It's For

The 347 Viton O-ring is aimed at technicians, equipment maintainers, and hobbyists who need reliable sealing in fuel systems, plumbing, pneumatic fittings, or firearms applications where heat and chemical exposure are concerns. It is particularly useful when replacing MSA fuel bottle seals, Remington barrel seals, or similar AS568A sizes where leak resistance and durability matter.

Users who should look elsewhere include those needing compatibility with strong alkalis, ammonia, amines, or glycol-based brake fluids, since Viton is vulnerable to those media. If you require softer or food-grade elastomers, consider alternative materials designed for those specific environments.

Pros & Cons

Pros

• High heat and chemical resistance from the Viton material makes it durable in demanding environments.
• Consistent sizing to AS568A means easy swap-in replacements for common sealed fittings and valves.
• Customers report good fit and leak resistance, making it a trusted choice for fuel bottles and seals.
• Pack of 10 provides spare parts and value for routine maintenance.

Cons

• Not compatible with certain chemicals such as low molecular organic acids, ammonia gas, and glycol-based brake fluids.
• 75A hardness may be firmer than desired for delicate, low-compression sealing tasks that require a softer elastomer.

Specifications

Material	Viton (fluorocarbon elastomer)
Durometer	75A shore
Inner diameter	4-1/4 in
Outer diameter	4-5/8 in
Width	3/16 in
Color	Black
Standards	Meets AS568A sizing

Our Verdict

The 347 Viton O-ring (pack of 10) is a solid choice for anyone needing a heat- and fuel-resistant replacement in standard AS568A sizes. It delivers practical value for maintenance use and applications exposed to fuels, high temperatures, or vacuum, though users working with strong alkalis or ammonia should choose a different elastomer. Overall it offers dependable performance and good value for routine sealing tasks.

Frequently Asked Questions

Is this O-ring compatible with gasoline and propane?
Yes; Viton is compatible with fuels, aromatic and aliphatic hydrocarbons such as gasoline and propane within its stated temperature range.

What temperatures can this O-ring handle?
It is rated for service from -15 degrees F (-26 degrees C) up to 400 degrees F (205 degrees C).

Will this work as a replacement for MSA fuel bottle seals?
Customers report these O-rings fit MSA fuel bottles and similar AS568A-sized seals, providing good leak resistance and durability.